Intel P80C39 MCU

[Johnny10]

Does anyone have acess to a P80C39 Intel chip from mid to late 80's  Zymos technology.
Blew one of these up on my Sencore LC102 unit.

Looking to replace.

[Roeland_R]

I found the p80c39-7 at AliExpress. Don't know if it's the same.

[wraper]

It can be replaced with any flavor of 80c39 in vast majority of cases. Get one from ebay or some other place where you can find.

[amyk]

The 8039 is ROMless so you can replace it with any equivalent.

http://www.jameco.com/1/1/4108-80c39-microprocessor-8-bit-27-i-o-11mhz-dip-40-intel-series.html

[Johnny10]

I ordered the 11MHZ version.

Checking my parts main board has separate 6mhz and 3.57mhz clock crystals.

[Johnny10]

Just to finish up this thread...
Ordered a NOS 80C39 made from Phillips dated 93.

Doesn't work.

As another forum remarked in the MicroController section.
And he was correct.

Some versions, such as the OKI Semiconductor MSM80C39, are "improved" with extra features such as additional instructions. Whilst supposedly backward compatible with the original INTEL 80C39 with properly written code, it could behave completely differently if, for example, the code happened to have errors which execute some of the new instructions which were simply ignored by the original version.

National Semiconductors, NEC and AMD, Toshiba (and probably many others) made 80C39s which were functionally identical to the INTEL parts but there is always the possibility of failure due to small differences in power consumption, I/O drive capabilities, input thresholds, reset level threshold etc. Also crystal oscillator variances may mean that not all crystals are guaranteed to work with all the different manufacturer's parts. If the circuit was properly designed then it will likely work fine with any of them but there is no guarantee. We fell foul of this with the bus port initializing into the input state after reset - but not before initially powering up in an output state on one manufacturers version but not on another, causing some to self destruct after enough power cycles.

If it is for a critical application or you only need a few I would try to get another ZyMOS part with roughly the same date code (47th week 1987) - later parts may have been manufactured with a mask shrink which would change the parts characteristics slightly - or even fixed some errata (bugs) which the code happens to, inadvertently, rely on. That will probably be difficult to source though. You might get lucky if someone here happens to know of any equipment which used those ZyMOS parts which might be easier to find than the bare chip.

[Bruce Abbott]

Here's the datasheet for the DMC8039 made by Daewoo ZyMOS. It does not appear to have any enhancements. Assuming that your replacement MCU is not a fake, you should consider the possibility that some other part has been damaged (ROM, latch, crystal...). For a quick check you could look at the ALE pin to see if it is pulsing, and monitor the port pins for activity.

Do you have any way to read the data out of the EPROM? For fault diagnosis you could try replacing it with another ROM which has a simple test program burned into it. If you want to go any further you should trace out the circuitry connected to the MCU.

[Kalvin]

What is estimated data retention time for an EPROM to hold its programmed state?

Edit: I tried to look that up from the AMD 27C256 datasheet but it wasn't specified. The Wikipedia states: "A programmed EPROM retains its data for a minimum of ten to twenty years,[5] with many still retaining data after 35 or more years". Depending how well the part has been erased and programmed during Sencore's manufacturing process, what has been the storage and operational temperature over the device's lifetime, and how "good" the part is (AMD wafer process at the time when the EPROM was manufactured) affects its ability to retain the data.

[Johnny10]

When you say the MCU is possible fake... what do you mean?
I see a lot of reference to fake chips but I am not sure I understand.

[Johnny10]

I had put my Sencore unit away for a few weeks and as I read your post I started thinking...
Why wouldn't this Phillips chip work. I purchased 7 chips from a gentleman in Germany after trying one I put it away as non-working.
Why not try this again, chips are from 1988.

Second chip I tried starts unit and works fine.

May have had something to do with shorted relay chip I disconnected "after" trying Phillips MCU.

Right now the only function I can use on the Sencore is the ESR test.
Trying with replacement MCU
ESR  test works!

Now when my new reed relays come in I can test for full functionality.

Thanks for moving me back onto this project!

[SeanB]

They take any old recycled chip with the same number of pins and the same ( or similar) package, and sand off the original markings then silk screen on the number of the fake chip they are selling. By the time you get the chip and find it is a fake they have gotten the money, changed the store name or are using a new name they registered a while ago to get good feedback ( sell to themselves or a confederate to build up false feedback) and are carrying on as usual.

[Rasz]

What is estimated data retention time for an EPROM to hold its programmed state?

Edit: I tried to look that up from the AMD 27C256 datasheet but it wasn't specified. The Wikipedia states: "A programmed EPROM retains its data for a minimum of ten to twenty years,[5] with many still retaining data after 35 or more years". Depending how well the part has been erased and programmed during Sencore's manufacturing process, what has been the storage and operational temperature over the device's lifetime, and how "good" the part is (AMD wafer process at the time when the EPROM was manufactured) affects its ability to retain the data.

anecdote from watching Computer History Museum - first Intel EPROMs, model 1702 (1971) are often unreadable by now, but not all of them. There are 1702s still working 100% ok.