3 Nov
2024
3 Nov
'24
2:48 p.m.
Though not Halt and Catch Fire you guys are forgetting the joy of self
modifying code.
That is how many PDP-8 programs worked. Even the bin loader where the
jump to loop instruction would be replaced with a jump to loaded program
start by the loader itself.
There were many programs that were very difficult to figure out what
they were doing, due to using this technique.
I love the PDP-8 but I don't miss self modifying code at all.
On 11/3/2024 4:03 PM, Paul Koning via cctalk wrote:
On Nov 3, 2024, at 4:59 PM, Mychaela Falconia
<falcon(a)freecalypso.org> wrote:
Paul Koning wrote:
Hint: you get to pick the initial values of the registers.
paul
1. Show a one-word PDP-11 program that writes all
of memory, in reverse order.
MOV -(PC),-(PC)
I remember this one from late-Soviet/early-Russian BK0010 hacker clubs...
BK0010 was a "home computer" built around 1801VM1 microprocessor, a
Soviet implementation of basic PDP-11 instruction set. No idea exactly
which DEC model it corresponds to, if any.
2. Show a one-word PDP-11 program that clears all
of memory,
in forward order, halting on completion.
This one I am struggling with - it's
been too many decades since I did
any PDP-11 assembly...