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Do these seem like real Z80 CPU's

A

alank2

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www.ebay.com

10PCS Z84C0020PEC DIP40 ZILONG NMOS/CMOS Z80 CPU CENTRAL PROCESSING UNIT NEW D1 | eBay

NEW, ORIGINAL parts. West Asia/Middle East. Australia/New Zealand. United Kingdom. France/West Asia.
www.ebay.com

I can't remember if I've ordered from this place before (some other IC), but I'd like people here who can tell whether an IC is real or not evaluate this a bit. Do they look like real CPU's?

I'm guessing they are CMOS and 20 MHz, right?
 
I am using one now, see here. I assumed when I bought it that it was not genuine. So far, it works in my TRS-80 M1. I didn't try to translate the site that you linked...does it identify any specific functional deficiencies?
 
I guess most people should know by now what the Chinese do with such chips: they remove or paint over the orginal inscription and re-label them, so they all look the same and like new. That does not mean you get fake chips. You may get a fully working Z80, or a dead one, or a different chip. Just the inscription is fake in any case.
 
Are there any decent ways to tell? For example, here is a search for z84c 10 (pcs,lot) dip - can you tell which (if any) might be legitimate Zilog product?

www.ebay.com

Z84c 10 (Pcs,Lot) Dip for sale | eBay

Get the best deals for Z84c 10 (Pcs,Lot) Dip at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!
www.ebay.com
 
generally they remark chips to pass it off as new parts with faster rating. I have a batch of 65C02s where half of them are remarked NMOS 6502s that would fail in enhanced IIe, and a bunch of PROM or masked ROMs that are remarked as Flash/EEPROMs.
you can try scrubbing the marking with acetone and see if they come off, though they've been employing laser etching for some time now. (never seen a people that's trying this hard to remark chips to cost only a few dollars.)
 
Most likely 4 to 8 MHz Z80 chips marked with new printing. Coming from China should seal the deal that the expression "Buy Beware" is never more true than things coming from there. Price alone should be the give away. I entered the P/N in a search and Digi-Key was the 1st link. Looking at the real Z80 photo there shows the ejector pin locations on the real and then the fake eBay parts are in different locations. So either from a different production line or fake, fake or fake.
 
One thing, with genuine vintage old stock chips, there is usually some degree of tarnishing of the pins from age. Also consistent with age appropriate date codes. If you see what is supposed to be a vintage chip with super bright & shiny Tin plated leads and perfect new looking markings, it is the result of being passed through a refurbishment process.

Now you might get lucky and it works, or it could be a completely different part. But even if it works, you have no idea what thermal, physical, and ESD trauma it has suffered in the past and all bets on reliability are off. I avoid these like the plague. In the refurb plants they use blowtorches on the pcb's and a machine shakes off all the parts.

It is harder for the fakers to deal with ceramic package chips, and they cannot bear to part with Gold, because they send those ones to precious metal recovery centers instead.

So if you see a vintage date code appropriate part with a ceramic package and gold plated pins, it has an extremely high probability of being a genuine part.

Also, many IC packages that were epoxy were unique, especially TTL's, the light grey of Signetics, the rounded corners of Motorola chips and the unique ones from Hitachi and the type of surface gloss, the fakers never get these subtle details correct. If you see a chip with a somewhat flat surface finish and laser engraved markings and numbers suggesting its a vintage TTL, forget it. It is some other later family of device, re-labelled.

Now not all China sellers send fake parts. There is a particularly good seller in Shenzhen, trying to set the record straight, his ebay shop is called Eric Woo's rare chips. Everything he has sent me has been genuine NOS, for example have a look at these genuine items, and he sends what is in the photo:

www.ebay.com

Motorola MCM68766C 8K x 8 nMOS UV EPROM CDIP24 x 1pc | eBay

We love to hear the voice of your advice!
www.ebay.com

It must be tough on him when others in China are send out so many fake and refurbished parts, pretending they are new.
 
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I’ve purchased IC from gc_supermarket before. They consistently delivered their products, they are relabeled, but most of them do work. Easy way to tell whether Z80 lots are relabeled is the same data code for all parts, but the bottom of IC may be different. In general, Z80 are almost certainly relabeled, but most are likely to work. You can tell NMOS fron CMOS by power consumption. CMOS are generally good to 25Mhz, possibly 30Mhz; NMOS are less predictable, most are good to 8Mhz, but some are 2 or 4 Mhz parts. By ‘good’, I mean they will run CP/M and pass zexall.com instruction tests. If you order, be ready to test the parts as soon as you’ve received them. eBay has excellent return policy if you test parts right away.
 
I managed to get some genuine old z80B's and z80H's from China recently. I knew they were genuine the moment I got them. However all of them failed. simple things like an address pin no longer able to pull high, or missing entirely. Data lines that don't work. . One or two worked *sometimes*. I was very disappointed. I get good results from some of the stranger brands, which also often look new ( ie, I get different date codes to match different packaging types ).

At some point I need to make myself a z80 tester. Something that loads up a minimal CP/M and has hardware serial/diags/external-memory-update and can take various clocks, with breakouts for test signals. Seems I will have to grade my chips myself and then I can follow Plasmo's suggestion.

China faking everything will haunt it forever. Have you ever seen the video clips?


That said, I buy a huge amount of old chips from China, and I'm actually pretty grateful they exist - Some (faked but working) chips are better than no chips.
 
It's possible to test in software for the difference between a genuine Z84C00 CMOS Z80 and an NMOS Z8400 using the undocumented "OUT (C),0" (0x'ED71') instruction, which outputs 0x'FF' on the Z84C00

See https://www.malinov.com/sergeys-blog/z80-type-detection.html and https://github.com/djtersteegc/z80-cmos-nmos-tester EDIT: and see Simon Cooke's Usenet post from way back at https://groups.google.com/g/comp.os.cpm/c/HfSTFpaIkuU/m/KotvMWu3bZoJ

The NMOS Z80H went to 8MHz officially, but can be over clocked. Plasmo knows that genuine Z84C00 20MHz parts frequently can overclock to and even past 25MHz. I have a couple of remarked Z84C00 20MHz parts that test as NMOS and won't clock above 10MHz; very likely Z80H parts.
 
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BTW everyone, Mouser does have two DIP versions of the Z80 in stock for now. I'm not sure why you can't find them with the search engine, the only way is to paste their part number in directly. Either z84c0008peg (9.74ea, 1734 in stock) or z84c0020peg (16.86ea, 713 in stock). Not as cheap as eBay, but for sure real parts.
 
Unfortunately, the only way to know you have real parts is to buy them direct from Zilog, and that's not possible anymore, so unless you can be certain your supplier got them from Zilog, then you run real risk that their supply is contaminated from stock that originated in China. This is a huge problem for Amazon, and other suppliers still buy out cheap inventory from other suppliers. This is the real value in faking chips and it compromises everyone.

:(

asia.nikkei.com

Fake chips slipping into supply chain, industry insiders warn

Semiconductor shortage pushes electronics manufacturers to risky procurement
asia.nikkei.com asia.nikkei.com
 
cj7hawk said:
Unfortunately, the only way to know you have real parts is to buy them direct from Zilog, and that's not possible anymore, so unless you can be certain your supplier got them from Zilog, then you run real risk that their supply is contaminated from stock that originated in China. This is a huge problem for Amazon, and other suppliers still buy out cheap inventory from other suppliers. This is the real value in faking chips and it compromises everyone.

:(

asia.nikkei.com

Fake chips slipping into supply chain, industry insiders warn

Semiconductor shortage pushes electronics manufacturers to risky procurement
asia.nikkei.com asia.nikkei.com
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Not really. If you look carefully at the Eric Woo link I posted above, you will see the tubes that the IC's came in, have the Zilog logo on the tubes. As yet, even the fakers have not gone as far as faking yellowed plastic storage tubes. But, if they ever figure this one out, its game over for us all. Darn it, I might have let the Cat out of the bag.

When you are buying vintage chips, there are many clues as to what is real and what is fake, you have to be a detective.
 
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Hugo Holden said:
Not really. If you look carefully at the Eric Woo link I posted above, you will see the tubes that the IC's came in, have the Zilog logo on the tubes. As yet, even the fakers have not gone as far as faking yellowed plastic storage tubes. But, if they ever figure this one out, its game over for us all. Darn it, I might have let the Cat out of the bag.

When you are buying vintage chips, there are many clues as to what is real and what is fake, you have to be a detective.
Click to expand...

I did notice the Zilog tube, and along with your endorsement, bought 5. He has 3 left.

But even then, if Zilog tubes mean better prices, they will fake those too. I think we're in a brief window during which the likelihood of real product is still high, but that will evaporate.

I found other chips that were clearly very old, so if they were faked, they were faked 20 years ago... then again, they were made by Japanese companies, so technically they were faked 40 years ago ;)

I also figure sooner or later someone will start making z80s again. Technology will reach the point it's possible. I'd love to see a 256 core 5 GHz Z80 ! :) And given the chip shortages in China, maybe they will start to use z80s and resurrect CP/M to keep their economy going ;)
 
You can still purchase stocks (with the appropriate paperwork) from people like Rochester Electronics. However, there are minimum order quantities and they are expensive.

If you are a hobbyist, probably way too expensive. If you are making kits or units to sell, maybe...

I haven't specifically checked their website for the Z80 though.

Dave
 
cj7hawk said:
I found other chips that were clearly very old, so if they were faked, they were faked 20 years ago... then again, they were made by Japanese companies, so technically they were faked 40 years ago ;)
Click to expand...
That is good news, practically any chip made by a Japanese company will be good, because the Japanese are fastidious perfectionists. This is why the world's best electrolytic capacitors are made in Japan and why the world's most reliable cars are Toyotas.

There was a short TV series called 5ive Days to Midnight, where a briefcase supposedly came back from the future with some vintage paperwork in it. One observer looking at it noticed that where the pages were held together with a paper clip, when that clip was removed, there was age appropriate rust from the clip on the paper and less yellowing where the clip had been, the kind of thing that takes years to develop.

The devil is in the detail when you are buying vintage parts.
 
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