31 Dec
2008
31 Dec
'08
7:12 p.m.
Tony Duell wrote:
I assume there's a limited number of writes to the microcontroller
program memroy, though...
I don;t know how much firmware space you have, but it would be nice if at
least Amigo and SS/80 could be fitted in together with a jumper/switch to
select between them. I'd also suggest some kind of configuration
switch-thingy to select the drive size -- some HP machines moan if the
drive is not the one they're expecting...
The HP drives work at a much lower level. The file system is managed by
the host computer. The commands to the disk drive unit read/write bocks
(essentially the same thign as sectors). It's up to the host to turn
those into a file system.
This is not as problematic as it may seem. The uIEC can auto-update the
firmware, so I could simply write a special version of the SW for
HPIG/GPIB (even different flavors for the various command sets) and the
owner can simply place the flavor desired onto a flash drive, turn on
the unit, and it will program itself with the correct DOS. You could probaly find an HP150 or an HP9000/200
machine fairly easily
on E-bay.
I am hopeful someone finds enough value in the possibility to provide a
unit for testing. Still, this is very premature, since I still need to
get the PET IEEE stuff working. It'll be a bit-bang approach, so save HW costs,
but I can wire up some
TTL logic if needed.
HO did bti-bang HPIB on several devices. The 82169 (HPIL-HPIB translator)
uses an 8049 IIRC, a custom HP buffer chip (which is nothing more than
line drivers/receivers) and a couple of TTL chips. The 98034 (HPIB
interface for the 98x5 machines) used HP's custom 'nanocontroller', some
standard buffer chips (3448s?) and a little TTL. Scheamtics for the
latter should eb on the Austalian Museum site.
-tony