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From: boB <boB@K7IQ.com>
Newsgroups: sci.electronics.design
Subject: Re: Zilog stopping Z80 production
Date: Wed, 24 Apr 2024 22:27:08 -0700
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On Wed, 24 Apr 2024 16:09:33 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 4/24/2024 1:42 PM, boB wrote:
>> On Tue, 23 Apr 2024 18:44:24 -0700, Don Y
>> <blockedofcourse@foo.invalid> wrote:
>> 
>>> On 4/23/2024 2:40 PM, boB wrote:
>>>> I miss playing with my old home built S-100 CP/M computer around 1980.
>>>> Those were really the fun days of computing and digital logic
>>>> circuits.
>>>
>>> Nowadays, the Zx80's appeal would be in controlling things.
>>> There's little that you can't now do *better* that you would
>>> previously have used a CP/M box for.
>>>
>>>> The other day after hearing the demise of the Z80, I ordered 2 of the
>>>> 20 MHz Z80  40 pin devices.  I did not even know there was a 20 MHz
>>>> version.  Not sure what I will ever do with them but who knows ?
>>>> Maybe I'll just look at them.
>>>
>>> Again, in the context of "control" (i.e., deeply embedded),
>>> you would likely also need similar speed grade peripherals
>>> to do anything.
>> 
>> Yes, I know.  Address decoders are a dime a dozen (almost) and any
>> other peripherals can either be made  or, I may actually have the
>> others laying around.  I save old ICs and have since the 1970s.
>
>But those devices won't be of the same (fast) speed grade as the
>processor.  Remember, all "external (to the CPU) interactions"
>happen at a rate defined by the system clock frequency.  So, the
>RETI daisy chain will have to operate "faster", the devices
>will have to put data onto the bus -- and take it off -- quicker,
>all rate generators (dividers) will have to be rejiggered for a
>faster input clock, any software delay loops (explicit or implied)
>will have to be rewired, etc.
>

The interface isn't that complicated with parts that are available
today to build something.  OR I could just run the part at 4MHz.



>>> I had a particular fondness for the '180 (and '7180!) as it
>>> wasn't crippled by the tiny address space (64K memory + 64K I/O)
>>> of the Z80.  Over the years, I've come to realize that you usually
>>> need more space for *code* than data!

I am not THAT interested in using an obsolete part. Just wanted one. I
may never even use it.

boB

>> 
>> Wasn't familiar with those 2.  Yes, I would run out of code space with
>> many micro controllers.  The was always programmed in assembler and
>> code was fairly smalll at that time.  Amazing we were able to get
>> along with less than 64K !
>
>The 180 gave you a seamless way to get to 1M of program+data.
>(Keep in mind that const data is still data!)
>
>The 7180 was a microcontroller variant -- 16KB EPROM (OTP)
>and 512B of RAM with a smattering of useful I/Os in a
>PLCC package.
>
>There were a couple of other 180 variants that offered
>specialized capabilities but I never had a use for those
>(*too* sole source; the 180 was eventually second sourced
>BY ZILOG  :> )