OT: Humor
Mikkel L. Ellertson
mikkel at infinity-ltd.com
Thu Mar 9 04:55:14 UTC 2006
tfreeman at intel.digichem.net wrote:
>
> <<sigh>> The old H89 running cp/m. Never did get around to trying H-DOS or
> whatever it was called, although I think it was pretty advanced for
> running on Z80. If configged properly, as I recall, you could run 1 5.25
> disk internal, two more 5.25 disks external, a 5 meg external hard drive
> (I think it was 5 meg although it was about 8 inches across), and I
> _think_ you could even get an external pair of 8 inch floppy drives with
> something like 256K capacity.
>
Yes, it could have a pair of 8" floppy drives. I had one of the
external boxes with the 2 8" drives up until 2 or 3 years ago.
I also had an interesting S-100 drive controller from another
company. (I forget the name.) It would control 4 5.25", 4 8" and
by using a daughter board, 4 MFM hard drives. It would also support
a memory drive using extended addressing static RAM. It would do DMA
transfer between memory pages, or from its disk buffer to RAM. It
would read the entire track of a floppy in one pass. It also did
deblocking from the drive sectors to the 128 byte blocks CP/M
used. It could also handle double density double sided drives. I
even had a 3.5" drive attached to it, and could read/write 720k
DOS disks on a CP/M system. You could also read/write 360K DOS
disks on 5.25 disks. But it would not handle HD 1.2M disks. I
was thinking of making a hardware/firmware change to use the data
clock setting for 8" drives with 5.25" HD drives. Then I could have
read HD disks. All the hardware was there for it, but who ever
designed the board didn't provide implement it.
Mikkel
--
Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!
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