ImageDisk
A
Diskette Imaging
program
for
Soft-Sector
Formats
Version 1.19
Revised 11-Jul-2012
Copyright 2005-2022 Dave Dunfield
All rights reserved.
ImageDisk
TABLE OF CONTENTS
Page
1. INTRODUCTION 1
1.1 License 2
1.2 System Requirements 3
1.3 Command Line Options 4
2. MAIN MENU COMMANDS 6
2.1 (S)ettings 6
2.2 (R)ead 10
2.3 (W)rite 10
2.4 (F)ormat 11
2.5 (E)rase 11
2.6 (A)lign/test 11
2.7 (C)lean 12
2.8 (T)est RPM 12
2.9 Track e(X)clusion map 13
3. FLOPPY DRIVE TYPES 14
3.1 5.25" Double Density 14
3.2 5.25" Quad Density 14
3.3 5.25" High Density 15
3.4 3.5" Double Density 15
3.5 3.5" High Density 16
3.6 8" Floppy Drive 16
3.7 Writing 40 track disks on 80 track drives. 17
3.8 Single-density and High-density drives 17
3.9 Easy/Cheap 8" drive adapter 18
4. TIPS AND TRICKS 21
4.1 PC floppy controllers are DIFFERENT! 21
4.2 Slowing the drive 21
4.3 Identifying an image 22
4.4 Writing a 250kbps image on a HD drive 22
4.5 Writing a 300kbps image on a DD drive 22
4.6 Reading DD/QD images on HD drives 22
5. MISC. Topics 23
5.1 PC Diskette Drive Types 23
5.2 DD Transfer Rate (250kbps <> 300kbps) 23
5.3 Double Stepping 23
5.4 Gap Lengths 24
5.5 Differences from Teledisk 24
5.6 256 Tracks / 255 Sectors? 24
ImageDisk Table of Contents
Page
5.7 Aligning a drive 25
6. IMAGE FILE FORMAT 26
6.1 Mode value 26
6.2 Sector size 26
6.3 Head value 27
6.4 Sector numbering map 27
6.5 Sector Cylinder Map 27
6.6 Sector Head map 27
6.7 Sector Data Records 28
7. IMDA: ImageDisk Analyzer 29
7.1 Introduction 29
7.2 Command line options 29
8. IMDU: ImageDisk Utility 29
8.1 Introduction 29
8.2 Command line options 30
9. IMDV: ImageDisk Viewer 31
9.1 Introduction 31
9.2 Command line options 31
9.3 Custom Character Sets 31
10. TESTFDC - Evaluate PC floppy controller 32
11. Converting from other image file formats 33
11.1 BIN2IMD: Binary to ImageDisk .IMD utility 33
11.2 TD02IMD: convert Teledisk .TD0 to .IMD files 36
11.3 DMK2IMD: convert .DMK images to ImageDisk .IMD 38
11.4 ANY2IMD : Convert ANY format to .IMD by floppy write/read 40
ImageDisk Page: 1
1. INTRODUCTION
ImageDisk is a program which reads entire diskette images into files
and can later recreate exact copies of the diskettes in order to:
- Archive diskette images for long term storage.
- Make it possible to transfer diskettes via the internet.
Unlike DISKCOPY, ImageDisk is not limited to PC format disks and PC
type diskette drives. It has been designed to handle any drive type
and disk format possible with the PCs disk controller hardware.
ImageDisk was created to address the problem of preserving system and
application diskettes for classic computers. Floppy disks are rarely
used with modern PCs, however they are the "bread and butter" of
classic systems. Without the system/application diskettes these
important artifacts of our digital history will become silent.
Please see the file HELP.TXT for help with common problems.
ImageDisk was created by:
Dunfield Development Services
115 Manion Heights Cres.
Carp, Ontario Canada
K0A 1L0
https://dunfield.themindfactory.com
"Daves Old Computers" <= Visit my collection
of classic computers.
ImageDisk Page: 2
1.1 License
This ImageDisk package is Copyright 2005-2012 Dave Dunfield, who
grants the following free license for non-commercial use. You may:
- Use the package for personal/hobby purposes for as long as you
wish, on as many computers as you wish.
- Redistribute copies of the package provided none of the
copyright material has been altered or omitted from the
distributed version. Additions to the package must be clearly
marked as such.
- Create/manipulate .IMD files with no restriction. The disk image
file format specification is hereby placed into the public
domain.
All rights and permissions not listed above are explicitly
reserved by the author.
Use of this software is entirely at your own risk. The author
makes no guarantee of the suitability of this software for any
particular purpose.
Copyright law prohibits duplication of material so protected. It
is your responsibility to determine the legality of any particular
use of this software. This package is NOT intended as a means to
bypass software copy protection.
By using this software, you accept all responsibility of any kind
which may result from such use. You agree to indemnify and hold
harmless the author and his agents from any action which may arise
from your use of the software.
ImageDisk Page: 3
1.2 System Requirements
ImageDisk requires a DOS based PC with an AT type floppy
controller. Although ImageDisk will run on a 4.77Mhz PC/XT type
machine, some of the analysis functions are real-time intensive
and best results will be obtained with a 486 class machine or
better.
ImageDisk *MAY* run under versions of Windows which provide direct
access to hardware (Win9x), however a pure DOS environment is
highly recommended. TSRs or other drivers which interfere with the
real-time operation of the system may cause problems with
ImageDisk.
ImageDisk will NOT run under operating systems which prohibit
access to the floppy disk controller hardware, such as:
WinNT/2000/Xp.
1.2.1 Floppy Diskette Controller
ImageDisk assumes that you have an AT compatible floppy disk
system. Ie: one on which the data rate can be set. If you use
ImageDisk with a PC/XT type diskette controller, you MUST use
the command line option LR=250 to lock the data rate at
250kbps. If you do not, then Image files will have incorrect
transfer rate values encoded within them.
Without this option, ImageDisk might "try" a data rate of
500kbps or 300kbps and find that it works - because it is
actually is fixed at 250kbps in hardware, and happily write an
image file indicating the wrong value.
NOTE: A PC/XT controller will NOT be able to read HD or 8"
disks. It is NOT recommended to use ImageDisk with a PC/XT type
floppy disk system.
Also note: Many floppy controllers are limited designs which do
not work well with non-PC formats. All PCs are NOT THE SAME!
ImageDisk Page: 4
1.3 Command Line Options
Use: IMD [[$]CMDfile] [options]
/4 - Assume 4 drives/FDC [2] *
/A - select drive A [A]
/B - select drive B [A]
/C - select drive C [A] *
/D - select drive D [A] *
/F - perform Full analysis [off]
/H - inhibit initial Help screen [enabled]
/K - Keep bad sectors [off]
/M - force Monochrome video [color]
/N - force Non-deleted data [off]
/S[addr] - use Secondary FDC at [372] [pimary/3F2]
C=1-255 - set number of Cylinders [80]
CP=[1-9] - number of Cleaning Passes [3]
D=path - default read/write Directory [current]
DS=0-1 - Double-Step (0=OFF, 1=ON) [Original]
FF=00-FF - Format Fill value [E5]
GF=0-255 - Format Gap [Calculated]
GW=0-255 - Write Gap [Calculated]
IL=[1-99] - InterLeave (blank=BestGuess) [As read]
LR=250/300/500 - Lock data Rate [off]
R=0-255 - select Retries [5]
S=1-2 - set number of Sides [Original]
SD=0-2000 - Delay after Step (ms) [55]
SR=1-16 - Step Rate (ms) [8]
HL=2-254 - Head Load time (ms) [254]
HU=16-240 - Head Unload time (ms) [240]
T5=250/300/500 - 500khz Translate [500]
T3=250/300/500 - 300khz Translate [300]
T2=250/300/500 - 250khz Translate [250]
TG=M[,cl] - enable Manual TG43 [Off]
TG=P1-3[,cl[,wf,wr]]- enable Parallel-port TG43 [Off]
X=track[,to_track] - eXclude entire track(s) [None]
X0=track[,to_track] - eXclude track(s) side 0 only [None]
X1=track[,to_track] - eXclude track(s) side 1 only [None]
'*' options require FDC supporting four physical drives (most don't)
Details of the meaning of most command line options can be found
in "MAIN MENU COMMANDS / Settings" in the description of the
corresponding Settings menu options.
1.3.1 Command Files
You can place commonly used command line options into a file
with a .CMD extension, and activate all of the options in that
file by specifying the file name on the command line. Options
must occur one per line. Blank lines, and lines beginning with
';' (comment) are ignored when the .CMD file is processed.
ImageDisk Page: 5
eg: ; Sample command file for DS in HD drive
; 40 Cylinders, double-step, translate 250<>300 kbps
C=40
DS=1
T3=250
T2=300
Normally, IMD will look for a command file in the current
directory, which allows you to easily keep command files
specific to your current task.
You can use a '$' prefix to cause IMD to look for the command
file in the IMD home directory. This accomodates general
command files that you wish to access from "anywhere".
When IMD starts, it looks for a command file names IMD.CMD in
it's home directory and if found, it will process it before any
other command files or command line options are performed. This
provides a way to customize the default settings of IMD to your
preferences.
ImageDisk Page: 6
2. MAIN MENU COMMANDS
The following commands are available from the ImageDisk main menu, by
pressing the bracketed letter in the command name:
2.1 (S)ettings
The Settings menu allows you to change various ImageDisk
operational settings. Use the Up/Down arrow keys to select one of
the following settings, and press SPACE to change it's value.
2.1.1 Drive
Controls which physical floppy diskette (A or B) will be
accessed by ImageDisk.
2.1.2 Cylinders
Sets the maximum number of cylinders which ImageDisk will try
to access.
In general: CYLINDERS should be set to the maximum number of
tracks which can be stepped on your drive.
During Reading, ImageDisk will not attempt to analyze or read
past this setting. Note that reading will still end if a track
is found with no data before then. (hint: If you need to skip
blank tracks, use the eXclusion map)
During Writing, this setting has no effect. ImageDisk will
attempt to recreate all cylinders that are defined within the
image.
During Align/Test, this setting has no effect (stepping is
controlled manually).
When cleaning the heads, this setting controls the range of the
"scrubing" motion throughout which the heads are moved.
ImageDisk Page: 7
2.1.3 Sides
Controls how ImageDisk treats the the disk as single or double
sided during an analysis. Has effect only for Analysis, Reading
and manual Formatting of a disk. During Writing, ImageDisk will
recreate both sides if present in an image.
Available settings are:
AS ORIGINAL : ImageDisk will examine the disk to determine if
the second side contains data.
ONE : Useful to prevent ImageDisk from detecting Side1 data for
previously used disks with valid but unrelated data on the
second side. Also speeds up analysis of single sided disks.
TWO : Use this to force ImageDisk to try and read a second
side.
2.1.4 Double-Step
Setting this option ON causes ImageDisk to step two physical
tracks for each logical track on the disk. This is necessary
when reading 48tpi (40 track) 5.25" disks on 96tpi (80 track)
drives. QD/HD drives have twice as many tracks within the same
diskette area as DD drives.
Setting the option OFF causes ImageDisk to step a single
physical track for each logical track in the image.
The setting AS ORIGINAL means that ImageDisk will examine the
disk and determine if double-stepping is required. This is
available for READING only - when WRITING a disk, you MUST set
this option to either ON or OFF. (The correct setting is
determined by the type of drive you are using and the disk
image you are writing - in general, if the disk image has 40
tracks in it, and you are using a QD/HD floppy drive, you will
need to turn this option ON - you may also need to select a
data rate translation).
ImageDisk Page: 8
2.1.5 R/W gap & Format gap
The GAP lengths cannot be read from the disk, and using the
wrong length can result in an unreadable copy. Unfortunately,
determining the correct gap length can be "magic science".
CALCULATED will use suggested values from the NEC databook if
it exists for the disk format being used, otherwise an estimate
is made based on the total track data size, sector size and
number of tracks/sector. This may not be correct, and may
result in a bad disk, or one which cannot be written. I have
therefore provided the option to force specific gap length
settings.
If you have problems, try increasing/decreasing the calculated
value Note that in general, the R/W gap must be less than the
FORMAT gap. FORMAT = total gap between sectors, R/W = gap after
READ/WRITE - and should fall somewhere in the middle of the
FORMAT gap.
Sometimes when a disk is made with an incorrect inter-sector
gap size, it will read fine, however attempts to write the disk
will corrupt it. This is because the inter-sector gap is too
small, and the partial gap written at the end of a sector
overflows into the next sector.
If you find this is happening, and you are unable to determine
good gap size values, another solution is to simply copy the
entire disk on the target system - this should restore all of
the gaps to the correct sizes as determined by your systems
disk driver.
2.1.6 Format Fill
This is the byte value used to fill freshly formatted sectors.
Normally, this gets replaced when the sector data is written,
howver any sectors marked as "unavailable" in the image will
remain filled with this value when it is written to a disk.
This setting also establishes the sector content for disks
which are low-level formatted (only) with the Format command.
ImageDisk Page: 9
2.1.7 Full Analysis
To save time, normally when ImageDisk has analyzed a track, it
performs only a "quick check" when moving to the next track -
If the transfer rate, density and sector size are the same, it
assumes the track will be the same as the last and proceeds to
read the sectors. It will perform a full analysis only if the
parameters change, or it encounters read errors on the sector
data.
This option causes ImageDisk to perform a full analysis on each
track - This increases the time needed to read a disk, but may
be required for disks with missing or oddly-numbered sectors on
some tracks, or sector head/cylinder values which do not match
the physical track position on the disk.
2.1.8 Interleave
This controls how ImageDisk determines the Interleave factor of
the disk being read or written. ImageDisk trys to discover
Interleave factor by reading the sectors ids passing under the
head after an index pulse, however for disks which are
difficult to read, this is not reliable. The following options
are available:
AS READ : Sectors are read/written in exactly the order that
was encountered on the original disk/image file.
BEST GUESS : Examines sector order and determines the
interleave factor which most closely matches. Writes sectors
from lowest with this calculated interleave.
1-99 : Writes sectors from lowest with specified interleave
2.1.8.1 Interleave factor (skew) explained
Many systems offset the physical sectors written to a track,
so that extra sectors occur between sequentially numbered
sectors, providing extra time for the CPU to process data
between sequential reads. For example, consider a 9-sector
disk:
1:1 Interleave: 1 2 3 4 5 6 7 8 9
2:1 Interleave: 1 6 2 7 3 8 4 9 5
The 1:1 interleave disk will require only one disk rotation
to read all sectors, but only if the CPU is fast enough to
be ready for a new sector IMMEDIATELY after reading the
previous one. If the CPU is not that fast, it will take 9
revolutions. The 2:1 interleave disk takes two revolutions
to read all sectors, but it allows an extra "sectors worth"
of time between reads.
ImageDisk Page: 10
2.1.9 Retries
This controls the number of times that a disk operation will be
retried.
After one set of retries, ImageDisk will normally re-analyze
the disk to determine of the track format has changed.
Retries=0 is a special case which prevents this from happening.
This is useful if you want to quickly scan the disk to extract
readable sectors only.
2.1.10 Keep bad sectors
This setting causes IMD to try and recover data from sectors
which were read with data errors (bad CRC). When ON, IMD will
record data from bad sectors along with a flag indicating that
the sector is bad. When OFF, IMD will discard the sector and
report it as unavailable.
NOTE: IMD will warn you if you recreate a disk containing bad
sectors, however it is not reasonably possible to make the
newly written sector appear bad on the disk. If you later read
the disk the data will still be in error, however it will read
as a good sector!
2.1.11 Data rate translations
Data rate translation allows you to try to recreate a disk on a
different drive type from that on which it was originally read.
The most common/useful translations are:
250 -> 300 = Read on 5.25 DD, write on 5.25 HD **
300 -> 250 = Read on 5.25 HD **, write on 5.25 DD
** Normally you would also enable Double-Step on the HD drive.
You can see the transfer rates in an image with the IMDU
utility.
2.2 (R)ead
Prompts for an image filename, and a comment record, then reads
the disk as defined by current settings into the image file.
2.3 (W)rite
Prompts for an image filename, then writes the disk as defined by
current settings from the image file.
ImageDisk Page: 11
2.4 (F)ormat
Performs a low-level format of a diskette.
Drive, Sides, Step, Format-fill and Interleave must be established
via Settings.
Number of sectors/track, starting sector number, data rate,
encoding (FM or MFM) and sector size will be prompted for.
NOTE: This is a LOW LEVEL format only. ImageDisk does not know how
to establish a file system (high level format) for any operating
system. If you want to automatically create high-level formatted
disks for a certain system the easiest thing to do is to Read a
freshly formatted disk and create copies from that image.
2.5 (E)rase
Completely erases the disk to make it unreadable.
Drive, Sides and Step must be established via Settings.
The PC controller has no documented capability to erase a disk.
This works by formatting the disk with a extra-long sector at a
low data- rate, which overflows the track, wraps and overwrites
the ID field, causing the track to contain no valid sectors.
This may not work on some 8" drives and/or some floppy
controllers. If this command does not work, you may be able to
achieve a similar result by experimenting with F)ormatting large
sectors.
2.6 (A)lign/test
Performs diagnostics by continuously reading sector IDs passing
under the drive head. For each sector ID, outputs:
<cylinder> <head> <sector> <#match> <#fail>
#match and #fail are updated after each full revolution and show
the number of ID's on the track which MATCH the physical cylinder,
and the number of ID's which DO NOT MATCH the physical cylinder.
At each revolution, a tone also sounds which is higher in pitch
when more matching ID's are found. This allows you to adjust drive
alignment by ear.
The following indicators are updated in real-time at the top of
the screen:
F=fault R = ready D = double-sided
W=write-protect Z = track-0
ImageDisk Page: 12
2.6.1 Alignment/test Commands
The following command characters can be entered during
Align/Test:
A - re-Analyze track
B - toggle Beep on/off
D - read Data from all sectors on track
F - Format diskette track
H - toggle Head 0/1
I - write $CnHn.IMD with track data (must do 'D' first)
P - set format/write Parameters
R - recalibrate to track zero/Reseek current track
S - toggle single/double Stepping
W - Write data to all sectors on track
Z - recalibrate to track Zero (and stay there)
0-9 - seek to track 'n'*10 (00 to 90)
+/- - seek +/- one track from current position
X - eXit disk alignment/test function.
2.7 (C)lean
Although I do not generally recommend the use of "Cleaning Disks",
sometimes you don't have time to remove and disassemble the drive
and these are a required immediate solution to dirty heads.
When prompted, insert a "wet" cleaning disk and press ENTER.
This function will "scrub" the disk head back and forth in a
zigzag pattern.
NOTE: Make sure that CYLINDERS under Settings is set to match the
number of physical cylinders on your drive.
2.8 (T)est RPM
This function calculates the revolutions per minite of the
diskette drive. Note that this is a simple function which employs
only the standard DOS 55ms timer tick - The results will become
more accurate the longer you allow the test to run.
Note that the result is cumulative, and will not accurately
reflect changes to the drive speed. If you are adjusting the
drive, press SPACE to restart the calculation after each
adjustment.
ImageDisk Page: 13
2.9 Track e(X)clusion map
Sometimes it is desirable to exclude certain tracks when reading
an image (Unreadable, Unformated, incompatible with your
controller).
This function allows you to select tracks to exclude from the
image when reading/writing. Note that tracks not occurring in an
image will NOT be formatted or written when the disk is recreated.
Use the arrow keys to position the cursor on the track you wish to
exclude, and then press SPACE to toggle between:
= Exclude side 0 only
= Exclude side 1 only
= Exclude both sides (entire track)
ImageDisk Page: 14
3. FLOPPY DRIVE TYPES
There are many drive types that can be connected to a PC. Aside from
physical media, the charactistics which affect how a disk is read or
written are: Number of Cylinders, Rotation speed and Transfer rate.
Drive type Cyls Rpm Rate
---------------------------------------
5.25" DD 40 300 250
5.25" QD 80 300 250
5.25" HD 80 360 500/300
3.5" DD 80 300 250
3.5" HD 80 300 500/250
8" 77 360 500
Understanding these parameters and how they relate to the different
drive types is very important to using ImageDisk effectively.
3.1 5.25" Double Density
This is the standard 5.25" drive on most classic systems. It has
40 tracks, rotates at 300 RPM, and transfers at a rate of 250
kbps.
This gives it a normal formatted capacity of about 4600
bytes/track, which gives a total disk capacity of: 4600 x
40(Tracks) x 2(heads) = about 360k bytes.
3.2 5.25" Quad Density
This drive is very simlar to the 5.25" DD drive, the only
difference being that it has 80 cylinders instead of 40. It
rotates at 300 RPM, and has a data transfer rate of 250 kbps. This
makes it electrially identical to the 3.5" DD drive.
This gives it a normal formatted capacity of about 4600
bytes/track, which gives a total disk capacity of: 4600 x
80(Tracks) x 2(heads) = about 720k bytes.
The 5.25" QD drive is quite uncommon on PCs, however it does occur
on some classic systems.
This drive can read 5.25" DD format disks by enabling Double-Step.
Please read the note regarding track width when writing.
ImageDisk Page: 15
3.3 5.25" High Density
This drive has 80 cylinders, rotates at 360 RPM, and transfers at
a rate of 500 or 300 kbps.
At 500kpbs it has a formatted capacity of about 7600 bytes/track,
which gives a total disk capacity of 7600 x 80(Tracks) x 2(Heads)
= about 1.2M bytes.
The 300kbps data rate is for compatibility with DD/QD drives. Due
to the higher rotational speed (360 RPM), 300kbps results in the
same bit density as 250kbps on the slower (300 RPM) drives.
At 300kpbs it has a formatted capacity of about 4600 bytes/track,
which gives a total disk capacity of 4600 x 80(Tracks) x 2(Heads)
= about 720k bytes.
This drive can read and write 5.25" QD format disks, however it
will do so at a transfer rate of 300kbps. To create a true 5.25"
QD image you must translate 300kpbs to 250kbps when reading the
disk, and 250kbps to 300kbps when writing the disk.
This drive can read 5.25" DD disks by enabling Double-Step,
however it will do so at a transfer rate of 300kbps. To create a
true 5.25" DD image you must translate 300kpbs to 250kbps when
reading the disk, and 250kbps to 300kbps when writing the disk.
Please read the notes regarding track width when writing, and
single density operation with 5.25" HD drives.
3.4 3.5" Double Density
This drive has 80 tracks, rotates at 300 RPM, and has a data
transfer rate of 250kbps, which makes it electrically identical to
the 5.25" QD drive.
This gives it a normal formatted capacity of about 4600
bytes/track, which gives a total disk capacity of: 4600 x
80(Tracks) x 2(heads) = about 720k bytes.
The 3.5" DD drive is quite uncommon on PCs, however it does occur
on some classic systems and a few early PS/2 models.
ImageDisk Page: 16
3.5 3.5" High Density
This drive has 80 tracks, rotates at 300 RPM, and has a data
transfer rate of 500kbps or 250kbps.
At 500kpbs it has a formatted capacity of about 9200 bytes/track,
which gives a total disk capacity of 9200 x 80(Tracks) x 2(Heads)
= about 1.5M bytes.
The 250kbps data rate is for compatibility with DD drives. At this
data rate, the drive functions exactly as a 3.5" DD drive.
At 250kpbs it has a formatted capacity of about 4600 bytes/track,
which gives a total disk capacity of 4600 x 80(Tracks) x 2(Heads)
= about 720k bytes.
3.6 8" Floppy Drive
The 8" drive is rarely found on a PC however it occurs on many
classic systems. It has a different connector than PC drives, and
you will need to make an adapter to connect it.
This drive has 77 tracks, rotates at 360 RPM, and has a data
transfer rate of 500kbps. Aside from being three cylinders short,
it is otherwise very similar to the 5.25" HD drive.
Unlike the other disk types, 8" diskettes are physically either
single or double sided - the difference being the position of the
index hole.
A single-sided disk has a normal formatted capacity of about 7600
bytes per track which gives a total disk capacity of approximately
7600 x 77(Tracks) = about 600k bytes.
Double sided disks have twice this or about 1.2M bytes.
Some 8" drives may have a TG43 signal issue when used on a PC
floppy controller.
ImageDisk Page: 17
3.7 Writing 40 track disks on 80 track drives.
An 80 track drive has a narrower track width than a 40 track
drive, which means that the track laid down by the head is thinner
than that laid down by the head in a 40 track drive.
When writing a disk in an 80 track drive which has previously been
written on with a 40 track drive, some portion of the original 40
track data will remain at the edges of the new thinner track.
If you then attempt to read the disk in a 40 track drive, the head
will see two conflicting signals which may cause read errors.
It is best to use blank or bulk-erased disks when writing a
40-track image to an 80-track drive.
3.8 Single-density and High-density drives
I have encountered a some PCs which are able to perform single
density operations at 250 kbps (DD drive), but NOT at 300 kbps (HD
drive). If you are using an HD drive and are unable to read or
write single-density disks, try a DD drive.
I have a note on my web site describing a modification which
allows an HD drive to operate at 300 rpm and 250 kbps data rate.
ImageDisk Page: 18
3.9 Easy/Cheap 8" drive adapter
Begin with an ISA bus connector from an old PC - this is the
correct spacing for the 50 pin 8" drive, but too long. Cut down to
50 pins.
Salvage a 34 pin edge connector from a dead 5.25" drive - look for
one which has a "ground plane" connecting the odd numbered pins.
Leave about 1/2 inch of board under the connector, remove
components and carefully cut tracks to insure that the even number
pins are isolated from the remainder of the board.
Scrape away the solder mask to bare the ground plane. Position the
"board" between the rows of pins on the 50 pin connector, centered
from each end with the ground plane against the odd numbered pins
of the 50 pin connector. Solder the odd pins to the ground plane
and add wire extensions to insure that all 25 pins are joined
together.
Using 30 gauge "wire-wrap" wire, and being careful to only solder
to the very inner end of the "fingers" on the 34 pin edge
connector, connect the even numbered pins according to this
pinout:
PC(34p) 8"(50p) Description
2 TG43 (see Note)
8 20 Index
12 26 DS1(PC) -> DS0(8")
16 18 Motor ON/Head Load All Odd
18 34 Direction (Note) numbered
20 36 Step pins are
22 38 Write Data ground.
24 40 Write Gate
26 42 Track 0 detect
28 44 Write Protect
30 46 Read Data
32 14 Side1 Select
34 12 Ready
You will now have an adapter which can be plugged onto an 8" drive
and allows you to connect to a standard 34 pin 5.25" PC cable.
NOTE: This pinout connects DS1 on the PC (the standard for both
drive A or B with a twisted cable) to DS0 on the 8" drive. You can
leave the 8" drive jumpered as Drive-0, and connect it as either A
or B at the appropriate position on the PC cable.
ImageDisk Page: 19
3.9.1 Track > 43
Some 8" drives require a signal called "TG43" which indicates
that the drive is positioned to a cylinder greater than 43.
This is used to reduce the write current on inner cylinders.
The diskette controller in the IBM PC does not provide this
signal, which causes write problems on the inner tracks of some
8" Drives.
There are three possible solutions:
3.9.1.1 Operating without TG43 signal
Some drives do not require TG43. Examine the control board
on your drive. If Pin 2 of the 50 pin interface connector is
not connected, then your drive does not require TG43. If it
is connected, the drive MAY require TG43 - it may also be a
jumper selectable option, please consult your drive
documentation.
Since TG43 is used only during WRITE operation, you will be
able to read 8" disks. Writing may fail or be unreliable on
inner tracks.
You can also try tying TG43 permanently LOW or HIGH ... One
or the other may allow you to create disks which although
not correct, MAY be readable and can be copied on the
destination computer to create correctly written disks.
3.9.1.2 TG43 via modified drive cable
The floppy control chip in the PC provides TG43 and
DIRECTION on the same signal. When moving the head this
signal means DIRECTION. When writing the signal means TG43
(reduce write current).
IF your disk controller does not "remove" TG43 from pin 18
of the interface during write, and IF your drive is
compatible with the multiplexed signals, then you MAY be
able to provide TG43 to your drive just by connecting both
Pins 2 (TG43) and 34 (DIRECTION) of the 50 pin 8" interface
to pin 18 (DIRECTION) of the PC interface.
Note that although this works with some drives, it does not
meet the floppy interface standard which requires these
signals to be driven separately. Some drives will not work
in this configuration.
ImageDisk Page: 20
3.9.1.3 TG43 via parallel port
If necessary, the TG43 signal required by some 8" drives can
be generated with the parallel port, using this command line
option:
TG=Pport[,Cylinder[,wf,wr]]
port = Parallel port 1-3 or hex address [None]
Cylinder = Cylinder above which to reduce WC [43]
wf = Value to write for full WC [F0]
wr = Value to write for reduced WC [0F]
3.9.1.4 Manual TG43 control
If necessary, the TG43 signal required by some 8" drives can
be controlled manually (via toggle switch). You can set IMD
to pause for manual TG43 control when writing with the
command line option:
TG=M[,Cylinder]
Cylinder = Cylinder at which to pause write [43]
ImageDisk Page: 21
4. TIPS AND TRICKS
4.1 PC floppy controllers are DIFFERENT!
The floppy disk controller varies widely from one PC to another,
and MOST PCs have limited controllers designed only for the
formats used on PC disks. Many controllers cannot handle
single-density, or lock correctly with the small gaps used in some
non-PC formats.
In developing ImageDisk, I have tested with dozens PCs, and found
that only a few of them could read and write all the mixed density
formats that I was able to make work. Some could read all the
formats (with a high number of recoverable errors) but could not
write them all. The remainder could not even read all the formats.
What this means is that you may have to try a number of different
types of PCs before you find one that makes a good ImageDisk
system.
The ImageDisk package includes a floppy disk controller evaluation
program called TESTFDC - This program will check out your PC
floppy controller and report on it's capabilities. I maintain a
listing of test results for various mainboards and floppy
controllers on my classic computer website.
4.2 Slowing the drive
The 765 FDC used in the IBM PC has limitations which are stricter
than the WD 17xx/27xx controllers used in many vintage systems.
One such limitation is that the 765 cannot handle the smaller gap
times used on some disks, and can have trouble reading them.
A useful trick is to slow down the drive to around 290 RPM - this
often allows enough extra time that the 765 controller can handle
the disk.
Many disk drives have a potentiometer on the motor control circuit
board which allows adjustment to the drive speed. You can use the
Test RPM function to check your drive speed.
ImageDisk Page: 22
4.3 Identifying an image
If you receive a .IMD image and do not know what it contains, or
what type of drive it should be created on, you can use the IMDU
utility to learn more about the image:
- Hopefully the COMMENT shown at the top of the listing will tell
you what is contained in the image.
- The summary near the end will show the number of tracks of side0
and side1 information. If the disk contains only side0 tracks,
then it is single-sided.
- Look at the total number of cylinders for each side, normally:
40 = 5.25" DD
80 = 5.25" QD, 5.25" HD, 3.5" DD or 3.5"HD
77 = 8"
- Look at the transfer rate, normally:
250kbps = 5.25" DD, 5.25" QD or 3.5" DD
300kbps = 5.25" DD, 5.25" QD read on a 5.25" HD
500kbps = 5.25" HD, 3.5" HD or 8"
4.4 Writing a 250kbps image on a HD drive
When an image which was recorded on a 5.25" DD or 5.25" QD drive
at 250kbps is written on a 5.25" HD drive, it must be written at
300kbps to account for the higher rotational speed of the HD
drive.
You must therefore use Settings to Translate 250kbps to 300kbps.
For images containing 40 tracks (DD), you will also have to enable
Double-Stepping in order to write the image correctly.
See also the note on writing 40 track disks on 80 track drives.
4.5 Writing a 300kbps image on a DD drive
An image which was recorded at 300kbps on a 5.25" HD drive, can be
written on a 5.25" DD or 5.25" QD drive by using Settings to
translate 300kbps to 250kbps.
Note that a QD (80 track) image cannot be written to a DD (40
track) drive.
4.6 Reading DD/QD images on HD drives
A 250kbps DD/QD image can be read on a 5.25" HD drive, however it
will read at 300kbps due to the faster rotational speed of the HD
drive.
If you plan to give this image to others, it is recommended that
you use Settings to translate 300kbps to 250kbps before reading
the disk. This will result in an image file showing the true
250kbps nature of the original disk.
ImageDisk Page: 23
5. MISC. Topics
5.1 PC Diskette Drive Types
ImageDisk does not know or care what types of drives are installed
in your PC - it determines the correct transfer rate and type of
stepping required by analysis of the disk.
When writing a disk on a different drive type than it was
originally read on, you may need to set a data transfer rate
translation. For example, if recreating a 5.25" DD disk on a 5.25"
HD drive, you will need to translate 250kbps to 300kbps.
5.2 DD Transfer Rate (250kbps <> 300kbps)
ImageDisk determines the correct transfer rate for your drive when
reading a disk, and that transfer rate will be correct when
writing the disk on the same drive, however the transfer rate may
NOT be correct if you write the disk on a different drive type
than it was originally read on.
Specifically: Standard 5.25" DD drives operate at 250kbps, however
HD 5.25" drives on a PC operate at 300kbps when operated in DD
mode (this is because the drive rotates at 360rpm instead of 300
rpm - the actual flux density transition rate on the media will be
the same).
A DD image read on a DD drive has a data rate of 250kbps. In order
to write this to a HD drive, you need to write the data at
300kbps. Use settings to select: 250 kbps -> : 300 kbps
A DD image read on a HD drive has a data rate of 300kbps. In order
to write this to a DD drive, you need to write the data at
250kbps. Use settings to select: 300 kbps -> : 250 kbps
When reading DD in a HD drive, I suggest setting: 300kbps ->
250kbps The image will now indicate the normal DD data rate of
250kbps (even though it was read on the HD drive), and will
recreate correctly on a DD drive - HD users will have to set: 250
kbps -> | 300 kbps.
5.3 Double Stepping
Although ImageDisk can determine that Double-Stepping is required
when reading a disk (48tpi disk in 96tpi drive), it does not know
what types of drives you are using, and therefore cannot tell when
Double-Stepping is required when writing a disk.
You must therefore set the Double-Stepping option correctly when
writing an image back to a disk.
ImageDisk Page: 24
5.4 Gap Lengths
As far as I can tell, determing the correct inter-sector Gap
length is mostly "Magic Science" ... The NEC databook provides
tables of suggested gap lengths for common sector formats, however
no material appears to exist documenting how to calculate the gap
lengths for non-standard formats.
Please read the Notes on Gap Length under Settings.
5.5 Differences from Teledisk
Teledisk is a disk image program from a company called Sydex.
Until now, it has been the best available means to archive and
share disk images for classic computers, and it has become
something of a de- facto standard for this purpose. Sydex no
longer supports Teledisk, and is requesting that it be removed
from distribution. If you are familier with Teledisk - please note
the following:
- ImageDisk does not try to do everything for you - if you don't
know what you are doing, Teledisk will probably work better for
you. ImageDisk has more user controllable settings, and can do a
better job of extracting and recreating disk images when
properly configured.
- ImageDISK does not quietly generate garbage when sectors occur
on the disk but cannot be read - ImageDisk will report all read
and write errors in the main screen log.
- ImageDisk marks within the image when a sector could not be
read.
See: ImageDisk Utility.
- ImageDisk has a documented image file format, which means that
you always have the option of exploring other means to recreate
a disk This is a MAJOR problem with Teledisk, and the main
reason that I created ImageDisk.
5.6 256 Tracks / 255 Sectors?
All too often, we find a product in which some arbitrary limit has
been imposed based on "current standards", that causes problems
with future enhancements to that standard - a good example of this
is the floppy disk controller chips designed in the era of the 77
track 8" drive which generate an error if recalibrating the head
to track zero fails after 77 steps (this does not work on an 80
track drive).
In designing ImageDisk, I have chosen to provide support for all
of the capabilities of the 765 FDC. This means that as many as 256
tracks, and 255 sectors/track are configurable. It's not that I
expect such floppy drives will exist, however it is less likely
that ImageDisk will become "useless" because I chose an arbitrary
limit.
ImageDisk Page: 25
5.7 Aligning a drive
To properly align a disk drive, you need a special alignment
diskette and an oscilloscope, however with ImageDisks Align/Test
function, you can usually get "close enough" without special
tools.
NOTE: If you don't know what you are doing, you can damage your
drive, your PC and possibly yourself - Attempt this only if you
are familier with and comfortable working on mechanical and
electronic hardware.
When you execute the (A)lign/Test function, ImageDisk will enter a
continuous read loop, providing a running display of the number of
sectors read which match the currently seeked track ID, and the
number read which don't match. There is also an audible "beep"
which increases in pitch the more matching sectors are found.
How you physically adjust head alignment varies from one drive to
another. For some you loosen the stepper motor and rotate it. For
others, you loosen the whole head carrier assembly and there is
either a worm-screw or a slotted cam which moves it back and
forth.
To "best guess" align the drive, start with a diskette formatted
on a known good drive. Seek to various tracks, and adjust the head
position for the highest audible tones. Note the limits where the
tone starts to drop, and assume "dead center" between those limits
is the best alignment point for that track. Do this at several
tracks over the range of head movement and find the best
compromise for all positions. Confirm your results with several
other known good diskettes from other sources.
You should also check the track-zero detect switch. During the
Align/Test function, ImageDisk will show you the status of the
track-0 sensor at the top of the screen. Make sure that it comes
ON when you step to track 0, and goes OFF when you step to track
1. If not, you may have to adjust the sensor position.
Note that if you have either the alignment or track-0 sensor
wrong, you may not be able to adjust the other correctly. If the
drive is really bad to begin with, you may have to go back and
forth between the two a few times in order to get to the point
where you can make the correct adjustments.
ImageDisk Page: 26
6. IMAGE FILE FORMAT
The overall layout of an ImageDisk .IMD image file is:
IMD v.vv: dd/mm/yyyy hh:mm:ss (ASCII Header)
Comment (ASCII only - unlimited size) (NOTE: You can TYPE a .IMD)
1A byte - ASCII EOF character (file to see header/comment)
- For each track on the disk:
1 byte Mode value (0-5)
1 byte Cylinder (0-n)
1 byte Head (0-1) (see Note)
1 byte number of sectors in track (1-n)
1 byte sector size (0-6)
sector numbering map * number of sectors
sector cylinder map (optional) * number of sectors
sector head map (optional) * number of sectors
sector data records * number of sectors
<End of file>
6.1 Mode value
This value indicates the data transfer rate and density in which
the original track was recorded:
00 = 500 kbps FM \ Note: kbps indicates transfer rate,
01 = 300 kbps FM > not the data rate, which is
02 = 250 kbps FM / 1/2 for FM encoding.
03 = 500 kbps MFM
04 = 300 kbps MFM
05 = 250 kbps MFM
6.2 Sector size
The Sector Size value indicates the actual size of the sector data
occuring on the track:
00 = 128 bytes/sector
01 = 256 bytes/sector
02 = 512 bytes/sector
03 = 1024 bytes/sector
04 = 2048 bytes/sector
05 = 4096 bytes/sector
06 = 8192 bytes/sector
ImageDisk does not currently handle disks with differently sized
sectors within the same track (the PC FDC cannot write such
disks), however an extension to the .IMD file format has been
suggested to allow these type of disks to be represented:
A sector size value of 0xFF indicates that a table of sector
sizes occurs after the sector numbering/cylinder/head maps
(immediately before the data records) which contains one 16-bit
value (in little endian format) per sector which defines the
actual size of that sector.
ImageDisk Page: 27
6.3 Head value
This value indicates the side of the disk on which this track
occurs (0 or 1).
Since HEAD can only be 0 or 1, ImageDisk uses the upper bits of
this byte to indicate the presense of optional items in the track
data:
Bit 7 (0x80) = Sector Cylinder Map
Bit 6 (0x40) = Sector Head Map
6.4 Sector numbering map
The sector numbering map contains one byte entry containing the
physical ID for each sector that occurs in the track.
Note that these entries may NOT be sequential. A disk which uses
sector interleave will have a sector numbering map in which the
sector numbers occur in non-sequential order.
If ImageDisk is unable to obtain all sector numbers in a single
revolution of the disk, it will report "Unable to determine
interleave" and rearrange the sector numbers into a simple
sequential list.
6.5 Sector Cylinder Map
This is an optional field. It's presense is indicated by bit 7
being set in the Head value for the track.
When present, it means that the cylinder values written to the
sectors do NOT match the physical cylinder of the track.
The Sector Cylinder Map has one entry for each sector, and
contains the logical Cylinder ID for the corresponding sector in
the Sector Numbering Map.
Reading a disk with non-standard Cylinder ID's will require the
use of the FULL ANALYSIS setting.
6.6 Sector Head map
This is an optional field. It's presense is indicated by bit 6
being set in the Head value for the track.
When present, it means that the head values written to the sectors
do NOT match the physical head selection of the track.
The Sector Head Map has one entry for each sector, and contains
the logical Head ID for the corresponding sector in the Sector
Numbering Map.
Reading a disk with non-standard Head ID's may require the use of
the FULL ANALYSIS setting.
ImageDisk Page: 28
6.7 Sector Data Records
For each sector ID occuring in the Sector Numbering Map, ImageDisk
records a Sector Data Record - these records occur in the same
order as the IDs in the Sector Numbering Map:
00 Sector data unavailable - could not be read
01 .... Normal data: (Sector Size) bytes follow
02 xx Compressed: All bytes in sector have same value (xx)
03 .... Normal data with "Deleted-Data address mark"
04 xx Compressed with "Deleted-Data address mark"
05 .... Normal data read with data error
06 xx Compressed read with data error
07 .... Deleted data read with data error
08 xx Compressed, Deleted read with data error
ImageDisk Page: 29
7. IMDA: ImageDisk Analyzer
7.1 Introduction
IMageDisk Analyzer (IMDA) is a utility which examines an ImageDisk
.IMD file and suggests possible drive types and options which may
be suitable to recreate a disk from that image.
NOTE: This is NOT intended as a replacement for "knowing what you
are doing". Getting the right drive type and settings often
requires knowlege about the drive type and format information of
the original system. IMDA will make suggestions as to what
drives/settings could be used to recreate an image, but it does
not know of the resultant disk is suitable for that system or your
particular use.
7.2 Command line options
Use: IMDA image[.IMD] [options]
opts: /Q - Quiet: inhibit informational output
8. IMDU: ImageDisk Utility
8.1 Introduction
IMageDisk Utility (IMDU) allows you to manipulate ImageDisk .IMD
files. The functions which can performed by IMDU are:
- Display track/sector detail.
- Compare two .IMD files.
- Merge two .IMD files, extracting missing tracks and
sectors from one to complete another.
- Remove specific tracks/sides.
- Translate the data rate values.
- regenerate track data with a new interleave factor.
- Compress/Expand "all same" sectors.
- Convert .IMD file to raw binary .BIN format.
- Extract, Append and Replace the image comment record.
ImageDisk Page: 30
8.2 Command line options
Use: IMDU input-image [[merge-image] [output-image]] [options]
opts: /B - output Binary image
/C - Compress "all-same" sectors
/D - display track/sector Detail
/E - Expand compressed sectors to full data
/M - ignore Mode difference in merge/compare
/NB - force Non-Bad data
/ND - force Non-deleted data
/Q - Quiet: supress warnings
/Y - auto-Yes (no overwrite prompt)
AC=file[.TXT] - Append Comment from file [none]
EC=file[.TXT] - Extract Comment to file [none]
F=xx - missing sector Fill value [00]
IL=[1-99] - reInterLeave(blank=BestGuess) [As read]
RC=file[.TXT] - Replace Comment from file [none]
T2=250/300/500 - 250khz Translate [250]
T3=250/300/500 - 300khz Translate [300]
T5=250/300/500 - 500khz Translate [500]
X=track[,to_track] - eXclude entire track(s) [None]
X0=track[,to_track] - eXclude track(s) side 0 only [None]
X1=track[,to_track] - eXclude track(s) side 1 only [None]
In general, IMDU works by reading the input-image, and writing the
output-image, performing whatever adjustments are specified by the
options.
If no adjustment options are made, then IMDU performs a compare of
the two images. (Adjustment options are: /B, /C, /E, /NB, /ND,
AC=, F=, IL=, RC=, T2=, T3=, T5=, X=, X0= and X1=).
If three image file names are provided, IMDU will merge the first
two, combining missing data from one into the other and write the
final combined image to the output file. Adjustment options may
also be applied during the image merge.
The /B option causes IMDU to remove the comment and all formatting
information, outputting what is essentially only the raw sector
content of the disk. This is useful for many emulators and other
disk image manipulation utilities which do not understand the
embedded format information in a .IMD file.
When using /B, IMDU automatically outputs the sector data in order
by logical sector number (ie: removes interleave), however if you
wish the sector data to be output in some other order, you can use
the IL= option to re-interleave the output order.
ImageDisk Page: 31
9. IMDV: ImageDisk Viewer
9.1 Introduction
IMageDisk Viewer (IMDV) is a utility which lets you easliy look
through the content of an image file, and optionally make
changes/patches to the content of individual sectors (not
recommended unless you really know what you are doing).
IMDV is a low-level tool which presents the data content of
sectors in the image file in hexidecimal dump format with either
ASCII, EBCDIC or custom character-set display. IMDV does *NOT*
understand the arrangement of files, directories or other features
of logical volumes which may be contained in the image (these
things are highly operating system dependant, and ImageDisk does
not assume any particular operating system created the disks).
What IMDV does do is allow you to search through the disk image
sectors, view then in HEX/ASCII/EBCDIC/Custom, search for specific
strings, and also to extract and display all printable strings
occuring from a set point in the image.
9.2 Command line options
Use: IMDV image[.IMD] [options]
Opts: /C - Case-sensitive searches
/E - use Ebcdic displays
/I - ignore Interleave in sector ordering
/W - allow Write to file (edit)
C=file[.CHR] - use Custom character-set [none]
E=file[.CHR] - Edit custom character-set [no]
M=n - Minimum scan-string length [5]
S=file[.TXT] - extract scan-Strings to file [no]
W=n - Width of scan-string output [80]
9.3 Custom Character Sets
IMDV runs on a PC, which uses the ASCII character set. It
accomodate the viewing of images containing EBCDIC encoded
characters, an internal EBCDIC->ASCII translation table is
provided.
If you need to use a different character set, you can load your
own translation table. This table consists of exactly 256 bytes,
each byte containing the ASCII character which should be displayed
when the character code corresponding to the position in the file
is encountered. NOTE: This is a simple byte translation only. IMDV
cannot accomodate character sets of more than 8-bits, nor can it
accomdate character sets such as BAUDOT which use encoded shift
sequences to select banks of characters.
A very simple character set editor is provided with the
E=character-file option.
ImageDisk Page: 32
10. TESTFDC - Evaluate PC floppy controller
As noted in preceeding sections, PC floppy controllers vary widely,
and it can be tricky to find a system with all the capabilities you
need to backup and restore some non-PC formats.
This TESTFDC utility evaluates the floppy disk controller in your
system to determine how well it performs at single/double density at
various data rates. It also tests MFM operation with 128 byte
sectors. Many PCs cannot access these disk types. If you plan to use
ImageDisk to archive and restore non-PC format disks, this program
should help you find a PC thats up to the task.
Use: TESTFDC drive [type] [options]
drive: Physical floppy drive to test (A: - D:)
type: Override BIOS drive type:
360 = DD 40 track 1.2 = HD 80-track (5.25)
720 = DD 80 track 1.44 = HD 80-track (3.5)
opts: /D - skip standard Double-density test (should always work)
/R - please Read this!
R=file - Write final report to file.
/X - eXclude MFM/128 test
You will be prompted to insert low and/or high density media. TESTFDC
only writes to the top 5 tracks of the disk, allowing you to use a
single disk to boot and to test. TESTFDC should be run from a bare
DOS boot (no windows).
NOTE: I am attempting to build a registry of mainboard and add-in
floppy controllers and their capabilities. The latest version of this
registry can be found with the TESTFDC program at:
http://www.classiccmp.org/dunfield/img
If you test a system/controller not already listed, or exhibiting
results differing from those that I have on file - please use the
R=file option to save the TESTFDC report(s) and send them to me along
with:
- The manufacturer and model number of your mainboard or add-in
controller
- The floppy controller chip used.
ImageDisk Page: 33
11. Converting from other image file formats
The ImageDisk package includes several utility program which are
useful in converting other disk image types to ImageDisks .IMD file
format:
11.1 BIN2IMD: Binary to ImageDisk .IMD utility
The BIN2IMD utility converts raw binary disk images into ImageDisk
.IMD format by adding Mode, Cylinder, Head, and Sector information
to each track/side record.
BIN2IMD can be useful to convert raw disk images (such as those
used by many emulators) into ImageDisk images. It can also be
useful in converting images from other sources - even if those
images contain embedded format information, it may be easier to
convert them to raw binary format and then use BIN2IMD to generate
a .IMD file than it is to try and convert directly to the .IMD
format.
11.1.1 Command line options
Use: BIN2IMD input-file output-image [option-file] [options]
opts: /1 - 1-sided output
/2 - 2-sided output
/C - write Compressed sectors
/U - write Uncompressed sectors
/V[0|1] - Verbose output
C=text | @file - image Comment
N=#cylinders - set Number of output cylinders
DM[s]=0-5 - track Data Mode
SS[s]=128-8192 - track Sector Size
SM[s]=n[,n-n][n.#] - track Sector numbering Map
CM[s]=n[,n-n][n.#] - track/sector Cylinder Map
HM[s]=n[,n-n][n.#] - track/sector Head Map
The DM=, SS=, SM=, CM= and HM= options can all be applied to
both sides, or one side only. Example:
SM=1-9 <= Both sides
SM0=1-9 <= Side0 only
SM1=1-9 <= Side1 only
It is therefore possible to create disks which are formatted
differently on one side than the other (Most commonly used for
formats which require differing sector numbering and/or head
mapping on each side).
As a minimum, in order to generate an image, BIN2IMD needs at
least the following options applied to all sides that are being
generated:
N= (always applies to both sides), DM=, SS= and SM=.
ImageDisk Page: 34
DM= sets the Data Mode, which must be one of:
0 = 500 kbps FM \ Note: kbps indicates transfer
1 = 300 kbps FM > rate, not the data rate,
2 = 250 kbps FM / which is 1/2 for FM
3 = 500 kbps MFM encoding.
4 = 300 kbps MFM
5 = 250 kbps MFM
SS= sets the Sector Size, and must be one of:
128, 256, 512, 1024, 2048, 4096 or 8192.
SM= specifies the Sector Numbering Map, which also defines the
number of sectors occuring on a track. SM= may consist of any
of the following elements:
number = Single sector-number
number1-number2 = Series ranging from number1 to number2
number.times = Single value occuring multiple times.
Multiple elements may be combined into a map by separating them
with commas:
SM=1,2,3,4,5,6,7,8,9 <= 9 sectors from 1 to 9
SM=1-9 <= Also 9 sectors from 1 to 9
SM=9-1 <= 9 sectors from 9 to 1
SM=1,2-8,9 <= 9 sectors from 1 to 9
SM=1.9 <= Sector #1 occuring 9 times **
** This (1.9) is actually invalid since sector numbers may
occur once within a track, however this format is useful
in some of the other lists.
The sector mapping you specify MUST match the order in which
the sector data occurs in the binary file. If you wish to
create images with differing interleave etc. You must first
create the image with the pysical data ordering, and then use
the IMDU utility to re-interleave it.
HM= specifies a non-standard Head Numbering Map (if not
specified, all sectors are assumed to have the physical head
number encoded). The number of HM= entries must match the
number of sectors defined by SM=.
Here is an example where a disk is created which logicaly has
20 sectors on Side0, even though they are physically organized
as sectors 1-10 on Side0, and 11-20 on Side1:
SM0=1-10 HM0=0.10 SM1=11-20 HM1=0.10
NOTE: The HM0=0.10 isn't strictly necessary, since the default
head encoded for Side0 would be 0, however it has been included
for it's descriptive value.
CM= specifies a non-standard Cylinder encoding. Very rarely
used, this option operates similarly to HM=.
ImageDisk Page: 35
The /1 and /2 options are rarely used. These options exist to
inform BIN2IMD that a disk is single or double sided in cases
where it may not be able to determine this from the parameters.
/2 can be used when both sides are the same, and no Side1
specific options have been specified - Use /2 to let BIN2EXE
know that it should generate two sides (You could also just
specify one Side1 specific option as the presence of such an
option automatically sets double-sided).
/1 or /2 are also used in option files, when the number of
sides to be encoded changes part way thorugh the disk. An
example of this might be a disk which has system tracks on
Side0 only for the first two Cylinders, and is double-sided
after that. This is quite rare.
/V controls the output of Verbose information detail about the
diskette format being generated.
/V = Generate track format summaries only
/V0 = Generate no detail (Default - use this to turn
Verbose detail output OFF within an option file).
/V1 = Generate detail showing track format and map detail.
C= Specifies a comment to be included in the image. A single
line of text can be specified. To accomodate the fact that you
cannot put spaces in comamnd line parameters, any '~'
characters occuring in the comment text will be translated to
spaces. You may also include the content of a file with
'C=@filename' - in this case the text file is included with no
translation.
11.1.2 Mixed format disks - Command option files
BIN2IMD can create mixed format disks - those in which the
format changes from one track to the next. To do this, you must
specify the command options to specify the format into an
"option" file (type: .B2I), with each set of parameters on a
separate line preceeded by the Cylinder number where those
parameters are to take effect.
You may also use a command option file to establish commonly
used initial format option. If the first entry in the file is
assigned for Cylinder 0, then these options need not be
specified on the command line.
Blank lines, and lines beginning with ';' are ignored as
comments in the command option file.
;
; Example command option file to demonstrate a 40 Cylinder
; double-sided disk which is formatted 10x256 bytes sectors
; at 250kbps FM on the first two Cylinders, and 10x512 byte
; sectors at 250kbps MFM on the remaining 38 Cylinders.
;
0 N=40 DM=2 SS=256 SM=1-10 /2
2 DM=5 SS=512 SM=1-10 /2
ImageDisk Page: 36
11.2 TD02IMD: convert Teledisk .TD0 to .IMD files
Teledisk is a program which performs a similar function to
ImageDisk, and for many years was one of the most popular imaging
program which could handle non-PC formats. For this reason, it
became the primary method by which many people preserved and
exchanged system disks for classic computers.
Originally sold as a shareware product by a company called Sydex,
all rights to Teledisk were later sold to NTI, who no longer
supports it or offers it for sale. This puts Teledisk into a state
of limbo, as you cannot legally obtain or use later NTI versions,
and the Sydex shareware versions cannot be used beyond the
evaluation period without a purchased license, which you currently
cannot buy. This is one of several reasons I created ImageDisk as
a replacement for Teledisk. I urge anyone creating or manipulating
new diskette images to use ImageDisk instead of Teledisk.
TD02IMD reads a teledisk .TD0 image file, and reformats it into an
ImageDisk .IMD file. Once you have done this, you can manipulate
the disk and recreate it with ImageDisk and it's utilities exactly
as you would an image that you recorded directly.
Note that the Teledisk file format is closed and completely
undocumented. TD02IMD relies on information obtained by reverse
engineering and may not be able to handle all Teledisk images. I
recommend that you do not remove the .TD0 files until you have
fully tested the resulting .IMD images on your target system.
Use: TD02IMD filename [options]
Opts: /Dx,l,h - enable Debug options
/F - don't assume whole disk is FM if file FM indicator set
/L - don't convert 300kbps (LD in HD) to 250 (standard LD)
/Q - Quiet: less informational output.
/RF - remove Repeated (duplicate) sectors, keep First
/RL - remove Repeated (duplicate) sectors, keep Last
F=ACDIN - remove sectors based on status Flags
A=deletedaddressmark C=crcerror D=dos N=nodata I=noid
M=n - Maximum sector number (remove any higher)
W=CDHIN - inhibit Warnings:
C: CRC error (bad sector)
D: Duplicate sector numbers
H: Head not 0 or 1
I: No ID field - possible bogus sector
N: No DATA field
The /RF, /RL, F= and M= options are useful to remove bogus sectors
that TD sometimes inserts into a disk image when it has trouble
reading the disk.
ImageDisk Page: 37
Early versions of Teledisk use a single bit in the disk header to
indicate single-density, which suggests that it was "all or
nothing" - later versions have a bit in the track header, allowing
mixed single and double density tracks. I have made the assumption
that if the global SD bit is turned on, the image is from an early
Teledisk version and should be recreated entirely in single
density, however I do not know this for certain. The /F option
allows you to disable this assumption.
Debug options are mainly for my own use in resolving compatibility
problems, 'x' is a byte mask in hex, consisting of the OR of these
bits:
80 = Display disk header 02 = Internal sector info
40 = Display track headers 01 = Stop after one track
20 = Display sector headers
'l' and 'h' are low and high track numbers. If specified, Debug
output will only be produced for the indicated track range.
TD02IMD is a work in progress. If you encounter .TD0 files that it
cannot convert, please notify me with the details so that I can
look into it.
NOTE: The Teledisk file format allows for different sector sizes
within a track - the PC 765 floppy controller cannot format disks
in this manner, and ImageDisk does not currently support it (A
future version may support this ability as a "read only" feature).
Until such time as it does, TD02IMD will not convert such images.
ImageDisk Page: 38
11.3 DMK2IMD: convert .DMK images to ImageDisk .IMD
DMK is a popular disk image format for emulators, because it
stores all track data including formatting fields, and has no
compression options. This allows disks to be read/written by the
emulator exactly as a physical disk would be, and in many cases
can support copy protection and other features relating to
non-standard physical formatting.
DMK2IMD reads a .DMK format image file and converts it to an
ImageDisk .IMD format file.
Use: DMK2IMD filename[.DMK] [options]
Opts: /C[filename] - insert Comment record
/H - force High density (500kbps)
/L - force Low density (250kbps)
/S - force Single-density image
/UD - allow User defined DAM - treat as Deleted
/UN - allow User defined DAM - treat as Normal
/W - continue after Warning
O=file[.IMD] - specify output file [filename.IMD]
DMK has no capability to store a comment record. The /C option
allows you to provide a .IMD comment. If a file is specified, it
will be read and inserted into the comment record as ASCII text.
If no file is specified, you will be prompted to enter the comment
(press ^Z to exit).
DMK includes no information about the physical drive type or
controller settings used to create the image. In particular, it
does not contain any indication as to the data rate/density of the
original disk. DMK2IMD makes a "guess" based on the size of the
tracks, however you can override this and force /High or /Low
density.
DMK requires special handling for single-density. If a disk is
declared to be double-density, single-density data is recorded
twice to preserve sector spacing - DMK has a bit in the header
indicating single-density disks, however it's not obvious if this
has been supported from the very beginning. I have provided the /S
option to force DMK2IMD to assume a single-density disk (no double
data read).
The PCs 765 controller cannot handle the "user defined" DAM (Data
Address Marks) which occur in some DMK images - DMK2IMD will abort
if it finds such an address mark, however the /UN and /UD options
can be used to force it to treat the user defined DAM as either a
Normal or Deleted DAM.
The /W option allows DMK2IMD to continue processing after certain
errors which would otherwise be considered fatal:
ImageDisk Page: 39
Condition Action taken with /W
----------------------------------------------------
Bad Sector offset Sector not recorded
IAM not found Sector not recorded
ID crc error Sector not recorded
DAM not found Sector recorded, no data
Data crc error Sector recorded as bad
NOTE: The DMK format can represent disks with different sector
sizes or densities within a single track - the PC 765 floppy
controller cannot format disks in this manner, and ImageDisk does
not currently support it (A future version may support these
abilities as a "read only" feature). Until such time as it does,
DMK2IMD will not convert such images.
ImageDisk Page: 40
11.4 ANY2IMD : Convert ANY format to .IMD by floppy write/read
If you have on other way to convert an image file, the "last
resort" is write the image to a floppy disk using whatever tool
was designed for that purpose, and then read it back with
ImageDisk. This works, however it gets tedious because you need to
run both the disk-creator and ImageDisk separately for each file
you wish to convert, entering the filename twice (once for each
program), and noting and re-entering the comment field.
ANY2IMD simplifies this process process by building a list of
files of the foreign image type and automatically entering the
names into the programs, as well as capturing the comment field
displayed by the foreign imaging program and entering it into the
.IMD file.
The whole process looks like this:
- Set up a .INI file for ANY2IMD and the foreign disk creator
(see later)
- Set up a blank diskette in an appropriate drive, and enter the
command: ANY2IMD *.typ <= Command to convert ALL .typ files
- The foreign disk-creation program runs
- ANY2IMD enters keystrokes necessary to start creating the disk,
enters the filename, and display the file comment record (if any).
- ANY2IMD displays a "capture" box over the comment area. You can move or
resize the box with the arrow keys - F1 toggles moving (all corners),
and resizing (lower right corner). Press ENTER - ANY2IMD will capture
the comment from the screem, and continue.
- Proceed to create the disk, then exit.
- ANY2IMD creates a "blank" .IMD file containing the comment captured
from the foreign disk-creator program screen.
- ImageDisk runs...
- ANY2IMD enters the keystrokes to 'R'ead a disk, and enters the
filename.
- The comment is read from the file created above and displayed.
Press 'Y' to proceed.
- Edit the comment if desired, and proceed to make the disk.
- Exit ImageDisk - if there are more .typ files to process, the process
will repeat.
This seems like a lot, however it's really quite simple, and goes
much more quickly than manually entering the filenames and
comments. You can also automate the process of selecting drives
and options with the ANY2IMD options below:
ImageDisk Page: 41
11.4.1 ANY2IMD options:
ANY2IMD supports a number of options to control it's operation.
While these can be entered on the command line, it is usually
best to place these in a file called ANY2IMD.INI which will be
processed automatically when ANY2IMD starts. It first looks for
ANY2IMD.INI in the current directory, and then if not found,
looks in the directory where ANY2IMD.COM is located. Options in
the ANY2IMD.INI file must occur one per line. Blank lines, and
lines beginning with ';' are ignored.
WE=filename [options]
RE=filename [options]
Specify the Write/Read executable file.
You must enter a COMPLETE path - ANY2IMD does NOT scan your PATH.
- RE= will normally end with "IMD.COM".
Within the ANY2IMD.INI file you can also specify command line
options (you cannot do so on the interactive command line).
The special sequence ~FN can be used to substute the current
filename into the command line options.
WS=string
RS=string
Specify a "script" of keys to be automatically entered with the write
or read program runs. Note that embedded spaces can only be entered when
this option occurs within the ANY2IMD.INI file.
ASCII characters are entered exactly as they occur on the string, along
with special sequences identified by '~':
~~ = Single '~' character
~F1-~F0 = Function key 1-10
~S1-~S0 = Shift-Function key 1-10
~C1-~C10 = Control-Function key 1-10
~A1-~A10 = Alt-Function key 1-10
~EN = ENter
~BS = BackSpace
~TB = TaB
~BT = BackTab (Shift-Tab)
~ES = EScape
~IN = INsert
~DL = DeLete
~K+ = Keypad +
~K- = Keypad -
~LA = Left Arrow
~RA = Right Arrow
~UA = Up Arrow
~DA = Down Arrow
~HO = HOme
~EN = ENd
~PU = PageUp
~PD = PageDown
~WAn; = Wait 'n' milliseconds [note]
~FN = enter the Filename
~CC = Capture the comment record
~ST = Stop processing - press CTRL-END to continue
ImageDisk Page: 42
[note] Waiting works only when the application being executed
is polling for keys using INT 16h/AH=01h - If the application
requests a key using INT 16h/AH=00h, it will be suspended until
the next key, so waiting serves no purpose and is ignored (this
is normally used to wait until an application is ready for
input, but polls for other keys in the interm).
By carefully noting the exact keystrokes needed to prepare the
disk creation program or Imagedisk for the operation you
desire, you can use these options to automate those keystrokes.
CC=x,y,width,height
These options allow you to set the exact region of the screen with is
captured for the image file comment. The capture area is a box with the
X, Y coordinates giving the upper left-hand position (0,0=Top left),
extending to the right and down by the Width, Height values.
FD=x,y
Causes ANY2IMD to try and display the current filename at the indicated
coordinates on the screen when the write/read program is running. Choose
and area which does not interfere with normal screen display.
/P
Normally ANY2IMD will pause before running each Write or Read command,
allowing you to Proceed, Skip or Stop all commands - This is useful
when you are debugging your script strings, however once you have the
process working, the /P option can be used to disable the pause and
have ANY2IMD simply run the commands as quickly as possible.
/Ifile
Specifies the .INI file that ANY2IMD will read for it's default
options (Has no effect within the .INI file) - the default .INI
filename is 'ANY2IMD'.
ImageDisk Page: 43
11.4.2 Sample ANY2IMD.INI file using Teledisk
;
; Load all .TD0 (Teledisk) files
;
*.TD0
;
; Define Teledisk comment display/capture area
;
CC=4,10,73,9
;
; Teledisk executable file - no options
;
WE=c:\teledisk\teledisk.exe
;
; Write script: Use Teledisk to write image to floppy:
;
; ~RA - Right Arrow: move to 'Copy File to Disk'
; ~EN - ENter: proceed to next screen
; ~RA - Right Arrow: move to 'B:' (select drive B:)
; ~EN - ENter: proceed to filename input
; ~FN - send FileName
; ~EN - ENter: proceed to comment display
; ~CC - Capture Comment
; ~EN - ENter: Proceed to make disk
WS=~RA~EN~RA~EN~FN~EN~CC~EN
;
; ImageDisk exec - /H to skip help, /B for drive B:
;
RE=c:\imd\imd.com /H /B
;
; Read script: Use ImageDisk to Read floppy into image
;
; R - 'R': Activate Read function
; ~FN - send FileName
; ~EN - ENter: proceed
; Y - 'Y': answer 'Y' to continue prompt
RS=R~FN~ENY
;
; Put filename display at lower left of screen
;
FD=0,24