Re: Zilog stopping Z80 production

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  :> )