ABN.ISCAMS%usc-isid@sri-unix.UUCP (01/26/84)
Not many Decision I owners out there, but others may be using the Morrow
DJ/DMA Floppy Disk Controller, so this may be of net interest.
My Decision I ("the Toad") is running CP/M 2.2, has the regular DJ/DMA Floppy
Disk Controller for its single 8" DSDD drive, and the HDDCMA hard disk
controller board for its little 5 Meg Seagate 506 hard disk. The hard disk
has been run hard for the past year (lots of data transfers, editing,
programming, etc.), yet nary an error.
Shut down one night, no problems. Fired up the next night, and total dead!
I was set up to boot from an 8" floppy, and the software and system would
thereafter look to the HD as disk A. I had switched out Morrow's standard
configuration to boot into the monitor, then the 8" FD, and run BOOTMW to set
the HD as A.
Various tries, other boot disks, etc -- no luck. Reset the system to boot
from the FD; booted fine, but could NOT access the HD (the infamous "BDOS
Error on Select" or some such thing).
Reset the system (switches on the CPU board) to boot off FD and fall into
the monitor. Studied deep and long the Morrow documentation on the monitor,
the HDDCMA board, the Seagate, etc. (Sigh.) Poked around in the now-familiar
(well, kind of) monitor and checked the memory locations where the HDDCMA
was supposed to return messages after receiving commands. The code returned
in the monitor (per page 20 of the CPU manual) was H0400, which translated
to error in "Load constants" (?). The error code returned for the floppy
controller was F8000, "Controller not responding).
Delved deep and long into the CBIOS& source code, the disassembled (yeah,
some fun) HD format code, and could NOT figure out what might be wrong.
Called Morrow (the 800 number doesn't help for hardware problems - had to
dial a referenced long distance number for that -- but they DID give me
the local (Raleigh) repair facility) -- said they'd get back to me. (Not
yet, two days later).
Took out and carefully examined the logic boards on the hard disk. No
obvious damaged components. Carefully removed the HDDCMA hard disk
controller board, peered wisely at the components, pushed everything lightly
(you have to do that, you know), nothing obviously wrong.
After the entire weekend of this, and Monday thinking about it, went home
and called up the FORMATMW program (format the hard disk), acknowledging
that damage to the hard disk controller board or disk drive might now
totally waste my hard disk (I'd already written the data off, but luckily
all backed up! Drop dead, Murphy - Law #1 holds at Toad Hall).
The soft familiar sounds of the hard disk heads reaching out were a godsend.
The first message from the system acknowledging disk E (the hard disk)
existed appeared, "Formatting...". A very few minutes later the report
returned "No errors. Formatting complete." (or something like that!).
Yeay! Drive is perfect; after a solid year of smoking, not even one single
soft error. STAT E:DSK gave me true readings. Copied all the backup disks
back to the hard disk, nary an error. All CRC'ed just fine. Reconfigured
the system back to my original setup; all is well.
Only thing I can figure is SOMETHING reached out and hit my hard disk
right in the early portions that contain the physical description bytes
for the hard disk controller. After that happened, the controller couldn't
interpret that garbage as any hardware IT ever heard of, and would quietly
complain to two bytes in memory.
Most interesting (and terrifying) experience, yet turned out well. Sure
shows you gotta read the documentation (thanks, Morrow, for giving me all
that cryptic stuff the normal user would be totally disinterested in).
By the bye, I tried to add a set of 5 1/4" floppy drives to get me back
to more than a single-disk system (Qumes, model unknown, details unknown,
nondescript twin-disk case, supposedly DSDD 40-trackers, soft sector).
Naturally the only reference to 5 1/4's in my CBIOS& are for North Star
HARD sector ones -- same with the disk formatting source code (even the
old code out on SIMTEL20). Could NOT figure out how to hack the formatting
code to properly (1) tell the floppy controller it's talking to a soft sector
floppy drive and NOT a hard sector one (yeah, I know, Bit 1 of Status
Byte 1, but I just ain't that good at bit-setting yet!). The disk drives
would try to format a soft sector disk, would accept a SYSGEN without
complaints, but would always return a STAT C:DSK: as 40 track 160 KB
(the default in my CBIOS, I think), and would fail in disk writes (after
a few seconds) with "unable to close FOOBAR.TXT" or whatever.
Does ANYONE out there have that one wee little segment of code that
properly tells the DJ/DMA it's playing with a soft sector 40-tracker?
I need it for the CBIOS& AND the FORMATDJ source code.
I know this ran on and on, NetLandians, but you too may experience such
a disaster and not desire to blankly ship off your heart's delight to
the unfriendly hands of expensive repairmen.
David Kirschbaum
Toad Hall