2 ms·
And as far as capabilities go, the PDP-7 could address 64K of 18 bit words, more than double 1st generation microcomputers (those prior to the IBM PC and Apple
by hga 12y ago
And as far as capabilities go, the PDP-7 could address 64K of 18 bit words, more than double 1st generation microcomputers (those prior to the IBM PC and Apple Macintosh). Then again, I don't think it's generally known how much (very expensive, hand made) core memory was on that first UNIX(TM) PDP-7.
Maybe not that much, it next moved to the first model of the PDP-11, which had a max of 56 KiB memory of 8 bit bytes. Then to an 11/45, which could do 64 KiB of code, 56 KiB of data and 8 KiB of stack.
- kjs3 12y agoThe 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.