12 Feb
2003
12 Feb
'03
4:16 p.m.
----- Original Message -----
From: "ben franchuk" <bfranchuk(a)jetnet.ab.ca>
To: <cctalk(a)classiccmp.org>
Sent: Wednesday, February 12, 2003 4:29 PM
Subject: Re: Virtual vs Physical memory (was Re: Designing around a 6502 )
Roger Merchberger wrote:
I suppose then that the 8080 is a 16 bit computer because the HL register
pair could be used as a 16 bit pointer?
I am a LONG time programmer & system builder and what opinions I have were
developed on my own - through experience. Your mileage may vary.
One criteria you may have overlooked regarding the designation of a computer
as 8, 16, or other width is how wide is the memory bus? For the 6809, 6502,
8080, etc., the memory width is 8 bits.
Also, I didn't say that the 6809 and related chips weren't useful or good
chips - just that in my opinion (and the manufacturers as well), the 6809
was an 8 bit chip. There were some nice systems built using it; including
one I hand made for a friend. I think he ran FLEX on it.
Stuart Johnson
So where would that put the Hitachi 63C09?
It's 6809 compatible, but in
6309 mode, it has 4 8-bit registers, combinable to 2 16-bit registers
that you can do full 16-bit arithmetic on... but wait! There's More! No,
not Ginsu Knives.....
Having brought the subject up, I tend to think the 6809 is a 16 bit cpu
because of the good addressing modes and the Intel 8086 a 8 bit cpu
because of the lack of them. Also OS/9 for the 6809 was very
nice system. Ben.