36bit still in use ?

Johnny Billquist bqt at update.uu.se
Thu Dec 4 05:03:42 CST 2014

On 2014-12-04 08:25, Lars Brinkhoff wrote:
> Pontus <pontus at update.uu.se> writes:
>> Perhaps you could elaborate on the compatibility between the TOAD
>> versions and other PDP-10 processors. Also what operating systems do
>> they run, both previous and current versions?
> I'll contribute the technical information I have.  Happy to take
> corrections or additions!
> The TOAD-1 was XKL's first PDP-10 clone, created around 1994.
> The CPU is called XKL-1, and is a model B with an extended virtual (30
> bits) and physical address (33 bits) space compared to the KL10 model
> B.  It's clocked at 33 MHz, and has 128K of cache and 8K TLB entries.
> The microcode control store has 8K 128-bit words.
> Similar information for more 10s here:
> http://pdp10.nocrew.org/cpu/processors.html

As far as I can recall, the TOAD-1 is not compatible with the KL10B. I 
don't remember what the differences were, but I understood that TOPS-20 
had to be modified in an incompatible way to run on it. Which was 
unfortunate, in that SC also made extensions, but they were more in line 
with how the KL10B works. So we got two different branches when the 
architecture was expanded from the KL10B. Unfortunately I don't remember 
if it was the paging system or the I/O system where they diverged.

Someone who knows more details who can correct me on this?


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