Re: TI-H: Zunix?

To: <ti-hardware@lists.ticalc.org>
Subject: Re: TI-H: Zunix?
From: "Paul Kraszewski" <PKraszewski@BigFoot.com>
Date: Mon, 10 Aug 1998 12:07:22 +0200
Delivered-To: ti-hardware-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: ti-hardware@lists.ticalc.org


>Can UNIX or some variant be ported to the z80?  More specifically, the 
>TI-85?  This is probably wrong, but I had an idea for how it might work [...]


    I am not the ultimate judge, but:

    Did anyone think, why there is (was) no UNIX for Spectrum, C64 or Atari 130XE. Memory size? No. Data storage? No. User interface? No. Then WHY???

    There's one answer - UNIX requires hardware support. Z80, 6502, 8051, 8080 give no such support. These are single-task CPUs. UNIX it needs hardware protection of memory - softare simulation would take 99% of resources. This is meant not for as-is protection (meaning safety), but for convinient memory management, swapping and banking - in general, virtual memory support. UNIX needs flexible task switching support - directly related to memory management. Without it, there's no real multitasking (not to mention multiuser) OS. So, I think, we may forget *real* Win85 or ZUNIX (TI-UX?).

    Quite opposite is with TI92 - it is equipped with MC68000, CPU that directly supports multitasking systems (2 levels of software priviledge, easy task switching, simple memory management and even simplier protection). It is a base for AMIGA, MAC and some PDP computers. There's UNIX already ported to these platforms, and it should be relatively easy to adapt it to the 92.

           Pawel Kraszewski - mailto:pkraszewski@BigFoot.COM
   /\                         http://www.bigfoot.com/~pkraszewski
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