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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.os.linux.misc,alt.folklore.computers
Subject: Re: The "Good" Old Days - Complete Specs for DX-10 Operating System
Date: Wed, 2 Oct 2024 17:59:40 +0100
Organization: A little, after lunch
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On 02/10/2024 17:43, Rich wrote:
> In comp.os.linux.misc 186282@ud0s4.net <186283@ud0s4.net> wrote:
>> The 990 series used the TMS-9900 chip and near variants.  This was an
>> odd chip - kept the CPU registers out in ordinary RAM and could
>> switch quickly between different sets of registers.  At that time,
>> the external RAM and CPU kinda ran at the same speed so little was
>> lost putting the registers in RAM.
> 
> The 6502 did something similar.  It wasn't as far down the path as the
> TI chip, but page zero (first 256 bytes of ram) acted a lot like an
> 'extended register file'.  There were even addressing modes that used
> two consecutive bytes of "page zero" as a 16bit pointer into the rest
> of the RAM one's system had installed,

The 6502 was an excellent little beast. I never programmed one myself, 
but I know people who did,  and my friend who worked on the original 
Acorn machines said it was pretty fast compared with a Z80 etc

Working with that is what led to the Acorn Risc Machine, which we all 
know and love as the ARM architecture

They couldn't afford to make a big chip, so they worked on an extremely 
small one, and gave it an instruction set that was minimal, but powerful 
.. Just like the 6502.



-- 
     “I know that most men, including those at ease with problems of the 
greatest complexity, can seldom accept even the simplest and most 
obvious truth if it be such as would oblige them to admit the falsity of 
conclusions which they have delighted in explaining to colleagues, which 
they have proudly taught to others, and which they have woven, thread by 
thread, into the fabric of their lives.”

     ― Leo Tolstoy