vspicer@ccu.umanitoba.ca (11/21/90)
Hello CP/M world... I recently got a "patched together" CP/M machine consisting of 2 8" single sided floppy drives, the guts of an Amdek composite monitor an ASCII encoded keyboard and a single board CP/M unit called a "Big Board II" made around 1982. It's a very nice single board computer with 2 serial ports, composite video output, SASI and "mini floppy" (5.25"??) interfaces and some other goodies. It boots fine with the CP/M 2.2 supplied and I can format 8" disks up to 670K each. My question is: does anyone have the firmware to let this thing use 5.25" disks drives as well? has anyone hooked a hard drive up to one of these things? I'm more than willing to hack with the guts of this thing if needed; they were kind enough to also supply full schematics for the thing. I've been told the "Big Board" design was widely copied by Osborne, Kaypro and Xerox for their CP/M machines. thanks vic spicer
donm@pnet07.cts.com (Don Maslin) (11/22/90)
The WD1771 FDC controller used in the Big Board is the same as used in
the Xerox 820 and is capable of using 5.25" floppies. What needs to be
done is to cut the data transfer rate from the 8" rate (500,000K bps) to
the 5.25" rate (250,000K bps) and, obviously, accommodate the 34 pin
connector on the 5.25" drive.
If you can find someone with schematics for the Xerox 820, you can see
exactly how they did it.
Emerald Microware, 12470 SW First, Beaverton OR 97005 sells parts,
software, and/or a kit to install a HD in the Xerox 820, amongst others,
which would perhaps work with the BB. Others may also.
Good luck.
Keeper of the CP/M System Disk | UUCP: {nosc ucsd crash ncr-sd}!pnet07!donm
Archives for the Dino(saur)SIG | ARPA: simasd!pnet07!donm@nosc.mil
- San Diego Computer Society - | INET: donm@pnet07.cts.comslsw2@cc.usu.edu (11/24/90)
In article <1990Nov22.030505.6665@simasd.uucp>, donm@pnet07.cts.com (Don Maslin) writes: > The WD1771 FDC controller used in the Big Board is the same as used in > the Xerox 820 and is capable of using 5.25" floppies. What needs to be > done is to cut the data transfer rate from the 8" rate (500,000K bps) to > the 5.25" rate (250,000K bps) and, obviously, accommodate the 34 pin > connector on the 5.25" drive. Or, you can just grab some 1.2 MB drives from an IBoringM AT. They run at 500 KHz, so should work just fine. -- =============================================================================== Roger Ivie 35 S 300 W Logan, Ut. 84321 (801) 752-8633 ===============================================================================
donm@pnet07.cts.com (Don Maslin) (11/25/90)
slsw2@cc.usu.edu writes: >In article <1990Nov22.030505.6665@simasd.uucp>, donm@pnet07.cts.com (Don Maslin) writes: >> The WD1771 FDC controller used in the Big Board is the same as used in > >Or, you can just grab some 1.2 MB drives from an IBoringM AT. They run at >500 KHz, so should work just fine. >-- Hmmmmmmm, let's see - single sided, single density. Why, that's a 241K byte 5.25" floppy! But seriously, that could be done although you would pay the space penalties previous, I think. - don Keeper of the CP/M System Disk | UUCP: {nosc ucsd crash ncr-sd}!pnet07!donm Archives for the Dino(saur)SIG | ARPA: simasd!pnet07!donm@nosc.mil - San Diego Computer Society - | INET: donm@pnet07.cts.com
wilker@gauss.math.purdue.edu (Clarence Wilkerson) (11/26/90)
I think the BBII supported DS DD 8" drives. So on a IBM HD drive you could get about 1.2 megs depending on your format. Zenith CP/M supported a 77 track x 2 sides x 9 sectors x 1024 byte format.