Odd "endianness" [was Re: RE: Base 64 posts to the list]

Eric Smith spacewar at gmail.com
Sat Dec 10 20:38:20 CST 2016

On Fri, Dec 9, 2016 at 12:47 PM, Rich Alderson <RichA at livingcomputers.org>

> [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.

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