28 Sep
2007
28 Sep
'07
5:50 p.m.
Dave McGuire wrote:
On Sep 28, 2007, at 8:03 PM, Tony Duell wrote:
>>> they did some really groady (cool) hacks (depends on your point
>>> of view) to use words as both instructions and data.
>> Maybe it was written by Mel, The Real Programmer? ;-)
>
> I'd love to see anyone write a self-modifying ROM ;-)
Actually I never said anything about writable, only that some
words were being used as both data and instructions. See
http://www.ak6dn.com/PDP-11/M9312/23-767A9/23-767A9.lst
on lines 59-79 for what I mean. This is the only boot prom that
I've seen that plays any tricks like this; all the others are
pretty straightforward code.
Funny that the boot prom had to do such strange things to interface
to the 'most intelligent' controller (MSCP), whereas all the other
dumb controllers (RK05, etc) used really simple boot code sequences.