14 Dec
2016
14 Dec
'16
midnight
From: Eric Smith
Sent: Saturday, December 10, 2016 6:38 PM
On Fri, Dec 9, 2016 at 12:47 PM, Rich Alderson
<RichA at livingcomputers.org>
wrote:
> [1] For non-PDP10 programmers: The original
architecture of the PDP-6
> and PDP-10 used an 18-bit (256KW) address space. The KI-10
> processor added a 22-bit pager and a concept of sections to the
> hardware.
As you say, the KI10 had 22-bit physical memory
addressing, almost
identical to the "KI paging" of the later Model A KL10. There were two
PTEs per 36-bit word in the page table, with the five of the 18 bits
being the APWSX properties, and the remaining 13 being a physical page
number. The 13-bit physical page number was concatenated with the
offset into the 512-word page (low 9 bits of the virtual address) to
get the 22-bit physical address.
However, the KI10 did not have any
"sections". Sections were introduced
with the Extended ("Model B", "KL paging") KL10.
I knew that was wrong just as soon as I had hit "Send", but I also knew
that I could count on one of the PDP-10 subgroup to fix that.
Thanks!
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/