HP1631D Logic Analyzer..Software???

Christian Corti cc at informatik.uni-stuttgart.de
Tue Dec 6 04:02:30 CST 2016

On Mon, 5 Dec 2016, Glen Slick wrote:
> I tried using ImageDisk on a PC to read the two HP 1630 3.5-inch
> floppies I have (10304 8085 preprocessor, 10342 HP-IB, RS-232C/V.24,
> RS-449 preprocessor). It appeared to be able to read the expected data
> just fine. Singled sided disk with 16 256-byte sectors per track
> (sector numbers 0 - 15) and 70 tracks.
> But it also seemed to detect a sector number 17 with no data in each
> track. Is that a normal 9121 low level format? I haven't tried to
> write a floppy back out using ImageDisk to see if the result is
> readable on a 9121 drive.

Funny that you mention that. I just came across that anomaly yesterday when I 
tried to create some disks for the HP150 with 9121 drive; the images are 
from the hpmuseum site and are in TeleDisk format.
I had a lot of trouble writing the images back. I wanted to use ImageDisk 
instead and tried the TD02IMD tool, but it failed miserably with the error
"Cannot do mixed sector size within track", even with the option M=15 
that should truncate every track after sector number 15.
I found out that a disk formatted in the 9121 has 16 normal sectors 
(numbered from 0 to 15) with 256 bytes each (size code 1), and one extra 
sector numbered 17 (there's no sector 16) with size code 5.
The solution to TD02IMD was to move the call of remove_sectors() *before* 
the three issame() calls. remove_sectors() is responsible to remove the 
unwanted sectors greater that 15 with option M=15. With that bugfix 
TD02IMD produces a correct IMD file that can be written back without 
problems, and the 9121 drive is very happy with that floppy :-)


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