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: <1991May5.022646.19235@sugar.hackercorp.com>
Organization: Sugar Land Unix -- Houston, TX
References: <1991May1.064455.3058@kessner.denver.co.us> <21135@cbmvax.commodore.com> <1991May3.041705.9907@kessner.denver.co.us>
Date: Sun, 5 May 1991 02:26:46 GMT

In article <1991May3.041705.9907@kessner.denver.co.us> david@kessner.denver.co.us (David Kessner) writes:
> IMHO, the 'bits' of an OS is the largest number it can put in a CPU register.

I have never, in my experience, seen an O/S with registers. That's hardware.
But then, if you wish:

> In this light, MS-DOS is a 16 bit OS.  Plain and simple.

Same is true for CP/M. HL on the 8080 is 16 bits wide. IX and IY on the Z80
are too. Or how about MCP, the O/S I worked on in my last job... the 1802
has *16* 16-bit registers! That's 12 (or is that 13) more than the 8088.

> Yes, I include the BIOS in the general scheme of MS-DOS.

Microsoft doesn't.

> Why?  For several reasons:

> 	The operating system (and/or device drivers) should deal with any
> 	hardware differences between machines-- and that is the role of the
> 	BIOS.

That doesn't handle the differences between the IBM-PC, HP150, Victor 9000,
TI-PRO, etc... or more recently the Data General 1...

> 	The BIOS is highly standardized.  In fact, they are (almost)
> 	interchangeable between machines-- as long as the machines have the

...exact same bugs and features as the IBM-PC/XT or /AT (including crummy
UARTS that don't support synchronous I/O)...

> 	The BIOS plays just a large of a role in the MS-DOS world as MS-DOS
> 	itself does.  When you do application programming, you try to call
> 	BIOS functions rather than MS-DOS functions (their faster, usually),
> 	etc.

I'm not discussing bugs and other implementation shortcoming in MS-DOS here.
Just the software architecture.

> And this makes it a 8 bit OS?

Yes. The fact that it doesn't provide a hardware-independent application
program interface for these resources. All an O/S is, at the bottom level,
is a resource manager. So that's what I look at: what resources it manages
and how complete the interface.

> From the software point of view (which is the view MS-DOS has) the
> 8088 and 8086 are identical (with a few very small differences) and are 16
> bits...

No, they're a hybrid between 8-bit and real 16-bit CPUs.

> I like how you said 'very similar' and not 'identical'.  The 8088 should
> be evaluated by it's own merits and not those of it's predicesors.

Yes, and on those merits it really sucks. Motorolas 16/32 and 8/16 bit CPUs
of the same era (68000, 6809) both blow it out of the water.

> In the same, MS-DOS should be evaluated by looking at MS-DOS-- not CP/M.

Why? CP/M was one of its competitors.

> This is more of a function of the hardware than MS-DOS.

Well look at the fate of computers that did a better job. If MS-DOS had been
a real 16-bit O/S instead of a port of an 8-bit one the HP150, Victor 9000,
TI PRO, and so on would have been successes.

> (Damn Compatibility)

Compatibility is only a problem if what you're compatible with causes problems.

> Yes, and no.  CP/M is more widely ported, true, and that's because of it's
> early history in a time where there was not a lot of hardware standards--
> much like the history of UNIX.  

There were not a lot of hardware standards when the PC came out, either.

> If you cant flame MS-DOS, who can you flame?

Damn good question.
-- 
Peter da Silva.   `-_-'
<peter@sugar.hackercorp.com>.
