4 Nov
2024
4 Nov
'24
12:23 p.m.
On Nov 4, 2024, at 12:15 PM, Mychaela Falconia
<falcon(a)freecalypso.org> wrote:
Paul Koning wrote:
Yes, that's the correct answer.
4 kW is the smallest PDP-11 memory I know of, though I don't have direct exposure to
the T-11.
paul
On the "one word clear", I missed a
detail. I pointed out you get to
initialize the registers. You can also initiate one memory word. In other
words: choose two words in memory, and registers contents, such that
execution will give you a memory full of zeroes and a halted machine.
OK, *now* the problem has a clear solution:
1) Write 000000 into memory word 015720;
2) Write 015720 [ MOV @-(PC),(R0)+ ] into the last word of system RAM;
3) Clear R0;
4) Jump to the last word of RAM where you wrote the 015720 instruction.
This solution does require that the system RAM be of certain minimum
size. Assuming power-of-2 sizes only, the machine must have at least
8 KiB of RAM, otherwise location 015720 does not exist. What was the
smallest RAM configuration on PDP-11?