Re: Zilog stopping Z80 production

On 5/13/2024 3:26 AM, albert@spenarnc.xs4all.nl wrote:

In article <v0jhbi$h25f$2@dont-email.me>,
Don Y  <blockedofcourse@foo.invalid> wrote:

On 4/27/2024 3:39 AM, albert@spenarnc.xs4all.nl wrote:

<SNIP>

I remember spending 2000 guilders in around 1980 for 16 K ram
for my Z80.
Just to discover that code in this ram couldn't run, because the
Z80 was too slow. Only useable for data.

>
Huh?  An opcode fetch takes the same amount of time as a data fetch.  The
opcode fetch also has a bit of extra time in the cycle (4 clocks vs 3)
to squeeze in a DRAM refresh (damn near everyone recognized this ability
when designing memory controllers; stalling the MCUs accesses just
to steal a bus cycle would be a significant hit on bandwidth).

 I'm pretty sure that was the situation. The machine served at a
clair voyance test system, and the program (assembler) fitted in
1 K Ram and the testresults were stored in the 16 (maybe 32 ram).
The idea was that you couldn't discriminate clair voyance for
paranormal communication, unless the result were checked by
a computer and not shown to any one.

Did the machine synthesize some random number, phrase, etc. and
the test subject expected to "guess" it?  I.e., enter his guess
on a keypad and the machine "scored" it?
Or, did the machine show a random number, phrase, etc. to a
"sender" who was intended to concentrate on that with the
idea that the test subject could "read their thoughts"?
(verified by entering them on a keypad)

I bought a DEC writer (5 by 7) for 2000 guilders to print the
test results, and use a black and white television for the
monitor. Those were the days.

Yes, increasing levels of integration have taken a lot of the
fun out of most designs.  I built a two-player "Breakout"
(video) game, in hardware, as an undergrad for one of my labs.
Nowadays, I'd spend a few hours writing a piece of code
that would do the same thing -- but, much less satisfyingly.
[with a hardware implementation, you were sorely pressured to
do a lot with very little; with a software (or VHDL) implementation,
it's just a few more lines of code...]

[There we no indications for paranormal happening.
The circuit to generate random targets was hardware and
pretty solid.]