6 Apr
2005
6 Apr
'05
4:14 p.m.
On Apr 5 2005, 19:21, Allison wrote:
It was the first 2901 'system' I ever worked on. I can remember some
train journeys between Bristol and London where I sat commenting the
microcode (I'd dumped out the ROMs -- remarkably easy on the RX02 since
grounding an IC pin that was otherwise pulled up to +5V disabled the
sequencer outputs and let you take over the PROM address lines). I wrote
a disassembler, produced a listing, and spent quite a time commenting and
understanding it. I learnt a lot from that.
-tony
The state machine is a simple but programable
non-von cpu that can do
the needed tasks to execute complex command to seek, read or write
a sector. The RX02 is a 2901based bitslice that does more as it
has to do the needed tricks for DD format.
Ah yes, I'd forgotten that. Thanks for reminding me where I'd seen
another 2901!