Hi All,
After all the replays and discussions I was more and more the
impression, that the images couldn't be in DSK, as this would mean some
extra work, as this format can't be created on a PDP.
To be more or less sure I have tried to open them with some DSK capable
tool, which I had on an older 486 based PC.
The outcome was a a message which told me, that the format is not supported.
So I have tied to reach Alan via Mail, and have asked about the format,
and that I had the hope to write the Images with PDP11GUI.
After a very short delay, I had this replay with all needed details, and
the OK, to post it here.
So you were right about Track0...
I will test it today's evening, and report back afterwards.
Many Greetings
Ulrich
Am 14.08.17 um 20:29 schrieb Alan R. Baldwin:
Ulrich,
The RX02 DSK images were created using the following RT-11
command file script:
create image.dsk/allocate:988
mount ld3: image.dsk
init ld3:
This results in a file of 988 blocks (505,856 bytes) in
length. The program PDP11GUI wants a file of 512,512 bytes
in length ... So this requires an explanation -
An RX01 or RX02 floppy disk is based on the original IBM
8" disk format of 77 tracks with 26 sectors per track and
for a Double Density RX02 has 2,002 sectors of 256 bytes each
yielding 512,512 bytes (or 1,001 blocks each 512 bytes long.)
However, DEC chose NOT to use the first track of the disk on
any RX01 or RX02 disk. Thus 76 tracks with 26 sectors per
track for the Double Density RX02 is 1,976 sectors of
256 bytes each yielding 505,856 bytes (or 988 blocks each
512 bytes long.)
In RT-11 the following command copies a disk file created
with the above command file directly and correctly to a real
RX02 disk:
copy image.dsk/file dy0:/dev
as the image disk has the same size as the active part of
the RX02 disk.
To use the PDP11GUI program you will need to prepend a file
of length 6,656 bytes to the TCP/IP files. The file content
is inconsequential. Copy the image file you wish to fix up
into a new location.
1) Open up a Command Prompt Window and
move to the directory containing the image file.
2) Make the fix up file as follows:
fsutil file createnew hdr.bin 6656
3) Concatenate the fix up file with the image.dsk file:
copy /b hdr.bin /b + image.dsk /b newimage.dsk /b
The newimage.dsk file will now load into the PDP11GUI program.
Since normally the RX01/RX02 drivers don't access track 0 I don't
know what the PDP11GUI program does with those extra 6,656 bytes.
Good Luck,
Alan
