3 ms·
The 11/45 has a 16-bit address space optionally expanded to 18-bits with an MMU so could do 256KB of memory. With the MMU, you could take advantage of split in
by kjs3 12y ago
The 11/45 has a 16-bit address space optionally expanded to 18-bits with an MMU so could do 256KB of memory. With the MMU, you could take advantage of split instruction and data memory, which gave a pair of 64k address spaces mapped into the 18-bit space.
No PDP-11 AFAIK have a separate, dedicated stack space. You're thinking of the 8k dedicated I/O page.
- hga 12y agoAh, yes, for the 11/45 I was referring to what a single program could do. However, as I recall (from the very early '80s when I was using both a 11/44 and 11/45), the MMU had a 8 KiB page size, so the natural thing to do was to divide the data as described, so a stack overflow would trigger a trap. Although after a bit of time with Google, I note the 11/40 manual says all PDP-11s have a location in which to put a stack boundary, so maybe that was a convention which matched what the MMU could do.