Program Challenge (was Re: z80 timing... 6502 timing)

From: Richard Erlacher <edick_at_idcomm.com>
Date: Mon Apr 19 18:20:55 1999

Please see embedded comments below.

Dick

-----Original Message-----
From: CLASSICCMP_at_trailing-edge.com <CLASSICCMP_at_trailing-edge.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Monday, April 19, 1999 1:56 PM
Subject: Re: Program Challenge (was Re: z80 timing... 6502 timing)


>>This is a valid viewpoint, though I think, ultimately, the question to be
>>answered pivots around which processor was potentially the most efficient
of
>>all its resources, including time. However, just the raw speed got a lot
of
>>discussion. In 1983, the 4MHz 6502 was "old hat" and the 8MHz Z-80H was
>>readily available. However, AFAIK the peripherals for the Z-80H were not,
>>and, in fact, I didn't ever see them. Somebody said they were out there
at
>>some point, but I've never seen them offered for sale.
>
>Of course, in the "real world", there are many other considerations
>to systems design other than processor speed and the "my CPU can beat
>up your CPU" arguments that are familiar to us from our schoolyard days
>(and seem to continue interminably here.)
>
>This is, for example, why the number of 8051-descended CPU's that have
>been shipped in the past 20 years is in the billions. (OK, very low
>billions, but it's there.) (1 billion == 10**9, to not confuse the
>folks who were educated outside the US of A.)
>
Yes, that's very true. The MC6809, for example, was touted as offering
greater ease of programming, hence, less effort, hence better fit into
applications with lower volume, among other interests. The 8051 is a
completely different class of device, though. Its core is unquestionably
the most widely used microcontroller core out there. There are those who
claim that the PIC (Microchip) is going to take that market over are
probably whistling into the wind, as although INTEL's share of that market
has declined, the overall numbers from the dozen or so makers of 8051-core
microcontrollers still dominate the market. The range of applications for
which it is suitable is MUCH more comprehensive than that of nearly any
other microcontroller, largely because there are so many variants with
features otherwise needing to be added on and thereby increasing cost and
circuit complexity. There are also some performance issues. There are some
really quite fast versions of this guy. It has architectural features which
reach back to its antecedent, the MCS48 family, yet its architecture
supports operations with a fairly standard register set, and a fairly
standard though minimal set of registers. It has several of these, as do
some other micros, but one doesn't have to use the multiple register sets if
it's not wanted.

The 8051 is a single-chip microcontroller, though. It isn't really intended
as the core processor of a more general purpose system though it's quite
capable. The 6502 and Z-80 were intended as highly flexible processing
units with external resources. Back when I was using the 6502 and Z-80, I
used an 8748 or a 68701 or '705 when I needed a self-contained
microcontroller.

Dick
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Received on Mon Apr 19 1999 - 18:20:55 BST

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