[HN Gopher] Testing the Z80 Chip with a 1970s Beauty
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Testing the Z80 Chip with a 1970s Beauty
Author : trakfactri
Score : 114 points
Date : 2024-11-11 20:11 UTC (1 days ago)
(HTM) web link (mtsi.substack.com)
(TXT) w3m dump (mtsi.substack.com)
| wrs wrote:
| Does anyone know what the tester for a 12-core 3 GHz processor
| looks like now?
| alain94040 wrote:
| Don't know what the latest is, but this from Teradyne was
| probably close:
| https://www.teradyne.com/products/ultraflexplus/
| raverbashing wrote:
| Interesting, looks expensive
|
| And I mean "chip factory expensive" not "Regular Joe"
| expensive
| femto wrote:
| Potentially the processor has Built-In-Self-Test (BIST)?
| Connect up the JTAG bus, send the right commands and the chip
| tells you that it is okay.
| jandrese wrote:
| > We had to be careful about those AC utility jacks. The tester
| ground was at -11 volts at several hundred amps. If you clipped a
| scope to a ground, it would happily melt the insulation off the
| scope probe until it stunk up the room and pooled on the floor.
| We had to use a three-prong adapter with the ground cut off.
|
| You don't get this kind of excitement anymore with modern
| electronics.
| fortran77 wrote:
| I have the same issue today when I fix old tube radios. Once
| side of the mains is connected to chassis -- and there are no
| polarized plugs. I use an isolation transformer, otherwise if I
| try to use a scope, I'd blow it out immediately--50% of the
| time.
| Aloha wrote:
| I am cheap.
|
| So I've never used an isolation transformer, I measure from
| test equipment chassis to chassis and check voltage
| potential, then roll the plug as needed.
| fortran77 wrote:
| It also reduces the risk of shock. Spend the $100 and get
| one.
| Aloha wrote:
| How so?
| dave8088 wrote:
| An isolation transformer will prevent electric shock
| should you accidentally put your body in contact with the
| hot side of the device and earth.
|
| https://en.m.wikipedia.org/wiki/Isolation_transformer#Ele
| ctr...
| formerly_proven wrote:
| An isolation transformer also completely prevents a GFCI
| from working.
| stephen_g wrote:
| Not exactly this, but you can easily make big sparks and trip
| RCD (GFCI) breakers if you accidentally probe something with a
| grounded scope that isn't isolated. In the past we've used
| battery powered scopes to get around this (cutting the ground
| pin off anything isn't a good way to do things!)
| PaulHoule wrote:
| First thing I made with Arduino was a tester for (much less
| complex) 54xx and 74xx chips.
| femto wrote:
| Typo? "ZIP DIP socket" should be "ZIF DIP socket", as in Zero
| Insertion Force?
| Affric wrote:
| Surely autocorrect.
| UncleOxidant wrote:
| I worked at Fairchild Sentry DTS in San Jose (at that time very
| close to the airport) circa 1984-1986 on the series 50 ATE. It
| was a beast. At the time it could clock & test up to 50MHz (hence
| the '50'). It was pretty much all ECL which would get very hot.
| Each unit shipped with a DEC VAX - that was my intro to VMS which
| had some interesting features like file versioning. I worked as a
| tech on the production floor building the 50. It was just being
| introduced and there were so many problems with getting them up
| and running. The systems had to be calibrated and that was done
| by changing the lengths of hundreds of delay wires on the
| backplane (in addition to digital delay-lines in the test head
| that could be automatically calibrated (over several hours) with
| the delay values being stored on disk). No two systems were
| exactly the same because of this (I'm sure this was also an issue
| with earlier ATE models as well). IIRC the 50 was "introduced"
| (announced) in '84 shortly before the time I started. I recall
| that we were way behind in producing them and there was lots of
| blame flying between production (us) and engineering - as in
| maybe they designed something that wasn't easily reproducible.
|
| In my next job I moved into an engineering role and I always kept
| that experience as a technician in the back of my mind: make sure
| what you're designing can be built with reproducible results.
| smoyer wrote:
| > ZIP DIP socket If that is referring to the picture above, my
| recollection is that it's a ZIF DIP socket ... We used those for
| writing [E][E]PROM. ZIF was zero-insertion-force.
| emulationonline wrote:
| I built something like a simpler version of this for testing some
| edge cases of the 6502. You can play with it through a browser
| here: https://chiplab.emulationonline.com/6502/
| DeathArrow wrote:
| >If you used a Z80 chip back in the 1980s, it almost certainly
| passed through a single room and its Fairchild Sentry 610 test
| system.
|
| I live in Eastern Europe, so I got access to a Z80 in the '90s,
| not '80s. And it was a clone, so it wasn't tested at Fairchild ,
| if it was ever tested.
| timonoko wrote:
| I was in Finnish Army and I had a sample of Russian 8080 in
| 1970's. We did not use it perse, but when Americans came with
| Comecon Trade Embargo - issues, we had this one example to show
| that advanced weapons we were developing were based on Russian
| technology.
| J05ephu5M13r wrote:
| Re the Z80 chip: I recall seeing a picture of a feller laying out
| the tracks with a roll of sticky tape on a drafting board.
| 082349872349872 wrote:
| From the neighbouring: https://mtsi.substack.com/p/we-picked-
| apart-the-milestone-hp
|
| > _I found out many years later that Mostek had put in special
| mask "cheats" to prevent people from copying our chip. Mostek co-
| founder and chief designer Robert Proebsting had discovered a way
| to put a pad on top of a silicon hill, but without connecting it
| to the obvious trace below. A copier would be unable to see this
| hill that served as an insulator unless they used a side-viewing
| microscope, which was rarely used. Copying was almost always done
| with a top-illuminated microscope_.
|
| > _That would throw off a copier who'd think it was just an
| ordinary via, and connect the trace to the layer below. This chip
| had a circuit to signal the specific 2+3 operation, and this
| would then be connected by the wrongly copied pad to the reset
| pin of the chip._
| matthewmorgan wrote:
| Reminded me of http://collapseos.org/
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