Intel 8002 NMOS version of 3002?

[wepwawet]

The early Intel naming scheme used 3 at first position for bipolar products. Just CPUs and the 3002 family didn't match this. My comment was to underline the date code guess.

[Elar]

[DaveC]

Great work! I looked at the document and you're absolutely correct about bipolar devices having 82XX P/Ns...I'm wondering if I can do a VCC/GRD resistance test on the inputs to determine whether they are bipolar or MOS assuming the 3002 pinout?

[chip68]

I should point out the reason for Intel choosing 8224, 8228, etc. was (in part) to maintain a consistent numbering scheme with second-sources Signetics and National Semiconductor, both of which had 8xxx TTL families.

As to doing a resistance test on the pins, I doubt that would be very conclusive, given that (1) the concept of "resistance" is meaningless when you're dealing with nonlinear devices like transistors, and (2) there are parasitic bipolar devices associated with any MOS integrated circuit, not to mention clamping diodes on the inputs for ESD protection.

- CMW

[DaveC]

I've measured inputs on TTL devices and because they are emitters generally, there is a certain normal range they have...if this is a bipolar device, I'm thinking that there might be a similar range. This could determine if the device is (a)3002 re-branded if the inputs match the device pinout or (b)not a bipolar device or doesn't match up to the 3002 pinout. Another thought would be to apply 5V across the suspected ground pin 14 and the supply pin 28 with all suspected inputs tied up to VCC through pullups measuring the supply current. If TTL there is a spec for that value. If MOS it should be much less.
Then if the suspected inputs are brought down to the ground rail one by one (power off) and power reapplied and supply current re-measured, there should be an increase that equates to either a TTL value or a very nominal increase that could indicate MOS.

[chip68]

Since you don't know what you have, you also don't know whether the pins you're tying to VCC or GND are inputs or outputs... Again, making anything you measure inconclusive.

It's one thing to test a known IC; it's quite another to attempt to ID a chip using ohmmeter measurements, which is generally fruitless. But be my guest.

- CMW

[debs3759]

[DaveC]

Hi, I appreciate the banter and skepticism and I got plenty of that when I sold off my C8086-4s awhile back, but I have a pretty good idea that these are the 3002/8002 for a lot of reasons.

If you compare the photos at CPU-galaxy world to those of my chips, you'll notice several important similarities, one of those is the bottom markings and another is the squared off top lid.

I did manage to strip off the black epoxy on one 8086-4 with a missing pin and discovered another 8086 marking underneath and 2 copyrights.

I've downloaded the 3002 data sheet and can see that this is a static clocked device much like the 6701 that I made a field demonstrator for back when I was the MMI sales engineer. I wasn't an Intel Salesman because I lacked the knowledge to engage in technical issues either. So I think I can handle some basic IC testing.

If you'd like to help, I'd appreciate any constructive comments about my planned procedures. Let me reiterate, the 8002 (if it is a 3002) will have the VCC at pin 28 and I can always check that with the short to substrate diode test on an ohmmeter. If that checks out, I can then proceed with the other pin testing using the 3002 pinout. And then I could also proceed right away to the procedure I outlined above. Or I could also build an demonstrator with input switches and LED outputs. Or I could take the easy way and just pop the top to get a microphotograph of the die.

I'd rather not destroy some value on a good device if I don't have to but maybe that's what it's going to take. My stripped 8086-4 still had trade value for some 6502/65C02s that I'm using on my AIM-65 expansion project. I enjoy the challenge of looking into the mystery before I decide my path as it appears that all of you do too!

[chip68]

I believe we have been trying to give you constructive criticism, and that is simply this: You can't determine whether it's a 3002, short of rigorous functional testing. Period. An ohmmeter will tell you nothing.

Regarding the similarities between the packages, again, this is a wild goose chase, as the packages were purchased from third-party vendors and had little to do with what was actually inside them.

If you do decide to pop the top off, I'm sure we'll all appreciate finding out what they are, conclusively. Speculation will always remain speculation.

- CMW

[DaveC]

[DaveC]

After thinking about the markings on these chips, I wonder if the "B" in front of the 8002 could refer to Bipolar since obviously the A & B after don't have any reference in variants in the 3002 docs that I have read. Also, the B on the package bottom could also have the same purpose for identifying it as a bipolar device.

[debs3759]

The 7952 datecode pretty much confirms that 8002 is a datecode, as they are too close together to be coincidence. It is normal (for most chips with a datecode top and bottom) for the dates to differ by a small time, and that would be a 2 week difference betwen manufacture of the package and building the chip.

I'm not saying it can't be a 3002, just that the top line of numbers is a custom part number, making it very difficult to properly identify.

[DaveC]

[debs3759]

Yeah, I'll take that as confirmation. Looks like you found an unknown part number

[doccybrown]

Research requires very rough methods sometimes!