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Re: The "Good" Old Days - Complete Specs for DX-10 Operating System

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On Wed, 2 Oct 2024 03:18:23 -0400
"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.
> 
> I remember fooling with this chip on a TI-99/4a home computer (which,
> tragically, horribly under-used the neat new 16-bit CPU). There were
> ASM commands for dealing with the register, 'context', shifting. By
> that means many users with their own space could be implemented
> directly with the hardware.

I've always found the 9900 concept interesting, although its core
assumption about memory speed doesn't really hold up today; much of the
architecture was eventually reincarnated in TI's MSP430 series micro-
controllers, but they ditched the memory-resident register file. But
for the time, context-switching certainly didn't get any faster than
that; only three actual registers to save, but you still got a
comfortably PDP-11ish environment from the programmer's perspective.

But yes, it's astonishing just how bad the TI-99 design was; a cascade
of bad decisions that turned what could've been a real contender in the
home-computer wars into an absolute joke. One of my oneathesedays
projects that I've toyed with for years (though never made any headway
on) is to roll up a homebrew system that does right by the concept...

> How it is now AIN'T how it always was.

And may it never be forgotten ;)

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The "Good" Old Days - Complete Specs for DX-10 Operating System "186282@ud0s4.net" <186283@ud0s4.net> - 2024-10-02 03:18 -0400
  Re: The "Good" Old Days - Complete Specs for DX-10 Operating System John Ames <commodorejohn@gmail.com> - 2024-10-02 09:15 -0700
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System John Ames <commodorejohn@gmail.com> - 2024-10-02 09:21 -0700
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System rbowman <bowman@montana.com> - 2024-10-02 16:35 +0000
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System John Ames <commodorejohn@gmail.com> - 2024-10-02 09:49 -0700
        Re: The "Good" Old Days - Complete Specs for DX-10 Operating System rbowman <bowman@montana.com> - 2024-10-02 22:28 +0000
          Re: The "Good" Old Days - Complete Specs for DX-10 Operating System John Ames <commodorejohn@gmail.com> - 2024-10-02 15:59 -0700
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Peter Flass <peter_flass@yahoo.com> - 2024-10-02 18:07 -0700
        Re: The "Good" Old Days - Complete Specs for DX-10 Operating System rbowman <bowman@montana.com> - 2024-10-03 01:46 +0000
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Peter Flass <peter_flass@yahoo.com> - 2024-10-02 18:07 -0700
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System scott@alfter.diespammersdie.us (Scott Alfter) - 2024-10-03 16:27 +0000
        Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-03 21:44 +0000
  Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Rich <rich@example.invalid> - 2024-10-02 16:43 +0000
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System The Natural Philosopher <tnp@invalid.invalid> - 2024-10-02 17:59 +0100
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-02 22:28 +0000
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Peter Flass <peter_flass@yahoo.com> - 2024-10-02 18:07 -0700
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System rbowman <bowman@montana.com> - 2024-10-03 01:38 +0000
    Re: The "Good" Old Days - Complete Specs for DX-10 Operating System scott@alfter.diespammersdie.us (Scott Alfter) - 2024-10-03 16:34 +0000
      Re: The "Good" Old Days - Complete Specs for DX-10 Operating System Rich <rich@example.invalid> - 2024-10-03 17:02 +0000
        Re: The "Good" Old Days - Complete Specs for DX-10 Operating System scott@alfter.diespammersdie.us (Scott Alfter) - 2024-10-03 21:54 +0000

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