Newsgroups: comp.sys.amiga.advocacy
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!menudo.uh.edu!sugar!peter
From: peter@sugar.hackercorp.com (Peter da Silva)
Subject: Re: 8-bit death
Message-ID: <1991May1.115856.13525@sugar.hackercorp.com>
Organization: Sugar Land Unix -- Houston, TX
References: <1991Apr28.162045.15585@daffy.cs.wisc.edu> <1991Apr30.112820.2451@sugar.hackercorp.com> <1991May1.064455.3058@kessner.denver.co.us>
Date: Wed, 1 May 1991 11:58:56 GMT

In article <1991May1.064455.3058@kessner.denver.co.us> david@kessner.denver.co.us (David Kessner) writes:
> In article <1991Apr30.112820.2451@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes:
> >In article <1991Apr28.162045.15585@daffy.cs.wisc.edu> dinda@cat55.cs.wisc.edu (Peter Dinda) writes:
> >> WRONG.
> >I love it how these college freshmen are so bloody sure of themselves.

> What makes _YOU_ so sure?

Experience, kid.

> >> MS DOS is a 16 bit REAL MODE operating system.  You may be getting
> >> confused since something like OS/2 1.x is a 16 bit PROTECTED MODE OS, while
> >> OS/2 2.x is a 32 bit PROTECTED MODE OS.

> >I'm not confused, bucko. You are. Look at what you wrote: full of intel
> >marketing terms for privileged mode, user mode, and so on.

> I would not call it marketing hype.  More like a difference in religion and
> it's terms.  

[stuff about motorola vs. intel]

Motorola calls it Supervisor mode, mate. Which is closer to the normal terms
for the thing.

> In _every_ respect, the 8088/8086 is a _16_ bit CPU.

It's a bag on the side of the 8080. Everything from the instruction set to
its registers (and the direct mapping from its registers to the 8080's)
indicates this.

> In this section,
> all addresses are calulated to 16 bits, then at the last moment it is added
> to the segment prefix, yeilding a 20 bit result (ok, there is one >16 bit
> thing in it).

Just like an 8080 with external banking.

> It is also a common mis-conception that the PC's intterupts are somewhat
> lacking.

There you go, quibbling about hardware again. I'm talking about MS-DOS. You
know, the software? It doesn't take advantage of any of that stuff. It is
STILL not possible to reliably use the serial port under DOS. You STILL have
to write your own device drivers. Bleagh.

> drivers are intterupt driven ... The only driver that is not is the DOS/BIOS
> serial drivers--

-- and the keyboard and the parallel port and the screen (remember all the
snow problems on the screen because the DOS drivers weren't synchronised with
the vertical blank?) --

> but _NO_ONE_ uses that driver, choosing to use their own custom
> drivers (this has been common practice since about 1983).

That's the point. Thank you for making it for me. And people write their own
custom handlers for the keyboard interrupt and so on as well.

> >No. Actually, MS-DOS is worse than CP/M. CP/M never got caught into the trap
> >of becoming specific to one piece of hardware.

> Wasn't CP/M specific to Z80 (and the like) CPU's?  I don't know which is
> worse, Z80 or MS-DOS...

CP/M ran on the Z80, the 8080, and the 8085. There were versions of CP/M for
the 8086 and 68000 as well. It ran on machines from homebrew S100 bus boxes
with TV-typewriters for terminals to 30-or-more user multi-CPU timeshared
office systems. It was basically *the* business system for its day, which is
why Seattle Computer and later IBM deliberately copied it for their box.

> The original dis-agreement was if MS-DOS is 8 or 16 bits-- and you know my
> opinions on that!

Sorry, mate. 8-bitness is in the blood. The 8088 was a bag on the side of
the 8080, and MS-DOS was a straight copy of CP/M, and there's no way to
get away from that.

> Then you ought know better!  Both you and I know that the 8088 CPU's have
... etc, etc, etc.

The Cosmac 1802 has 16 16-bit registers, with a RISC-like addressing mode,
hardware support for threads, and so on. But it's still a 4/8 bit CPU.
For that matter the Z80 has 16-bit registers (HL, IX, IY).

Look at the programming model. Not the manufacturers specs.
-- 
Peter da Silva.   `-_-'
<peter@sugar.hackercorp.com>.
