Intro to Microprocessors

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu Jul 19 13:02:16 2001

I have a couple of the ZAKS books and found them rather lame. The approach is
pretty conservative and some of the stuff he recommended in the books I got
didn't work as advertised. I don't know whether that's bad or not. I never had
the sense that his work got deeply enough into any specific processor that it
would help with the selection of one CPU over another, which is, after all, one
of the things one wishing to learn about microprocessors in general needs to
know, but the general field is covered in a very rudimentary way.

It's my belief that anyone who's learned how to read can get more from the data
sheets and data book app's information than his books offer. Now if you want a
cookbook approach, which he spreads from one CPU to another, it's there if you
want it. I suppose it IS better than no approach at all, and you've got to
start somewhere.

One thing I never saw in a book, particularly of this sort, was adaptive clock
switching. In one environment, I found that I could put a 16K block of fast RAM
in the bottom of the 6502 memory map and that it would, therefore, run the
software we were using about 4x as fast when I switched the CPU clock to 5 MHz
(pushing the Synertek 4 MHz 6502C processor just a bit) for cycles accessing the
bottom 16KB of memory. Since none of the I/O was slow, whenever I/O was used,
it cycled in 200 ns as well. Consequently, all the software I used back then,
which was assembled to load at 0x0200 and none reached above that 16K block,
except for the memory buffers used by the assembler and editor, ran at full
speed, only switching to 1 MHz when it reached outside that block or outside
I/O. It was wonderful to have that level of performance back in the late '70's,
particularly without paying the price of a fullcompliment of 55 ns RAM.

There were numerous others that I've run into over the years, but nothing really
interesting ever shows up in books about the basics. I guess that's as it
should be.

Dick

----- Original Message -----
From: "Eric J. Korpela" <korpela_at_ellie.ssl.berkeley.edu>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, July 18, 2001 6:14 PM
Subject: Re: Intro to Microprocessors


> > My take on learning microprocessors:
> >
> > 1) Pick a reasonable processor. An 8085, Z80,
> > 6502, or 680x is reasonable. A Pentium III is
> > not.
> 1a) Get a copy of the book "From Chips to Systems"
> by Rodnay Zaks.
> > 2) Read the data sheets. ....
>
> Other steps unmodified...
>
>
Received on Thu Jul 19 2001 - 13:02:16 BST