4 Nov
2024
4 Nov
'24
5:15 p.m.
Paul Koning wrote:
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?
M~