That chip seems to be the SAPROM, the station address PROM that contains the MAC address for the card. The printed label "F54FAC" most likely is the last three bytes of the MAC address contained in this chip, and the smaller 02608C is the vendor part of the MAC address. According to the IEEE OUI database, 02-60-8c is indeed assigned to 3com. This makes me wonder, because as I know it, the bit with value 02 in the first byte indicates a "private", "self-assigned" MAC address (just like the 10.x.x.x or 192.68.x.x IP addresses), so addresses like this should not be in the database.

You can possibly use the card without that chip (unless card detection fails), and might be able to force a valid MAC address using a driver option. A likely model number of that chip is (results of a google search for dip-20 PROMs by phillips) is 82S135.

Looks like a standard PAL/GAL chip too... I wonder if 3com decided to copy protect it?

Thanks for the info.
Found another card from SMC but it's DIP16.
Well, I just have to try it and see if it works without the chip.
These chips can't be read with a simple TL866 right?

luckybob wrote on 2020-09-09, 06:24:

Looks like a standard PAL/GAL chip too... I wonder if 3com decided to copy protect it?

It's too bad that most programmers applied readout protection automatically in their "production run" setting that automates program, verify and maybe even running some test vectors. I guess that's why you find very few non-protected PAL/GAL chips on commercial hardware. I still maintain this chip on this card being a simple (P)ROM, though. So, no read protection to worry about.

mkarcher wrote on 2020-09-09, 11:56:

So, no read protection to worry about.

Only one way to find out: someone who has the card could attempt to read the chip.

I have one of those ethernet cards, ill check it out when I can.

luckybob wrote on 2020-09-09, 15:11:

I have one of those ethernet cards, ill check it out when I can.

Thanks, I appreciate it!

got some time between class assignments

https://imgur.com/PgIDB5D

the chip's datasheet is ehre: https://www.datasheets360.com/pdf/8888944047117266061

A BIPOLAR PROM is a memory chip which typically contains a small amount of data, however the access time is very fast. These memory chips store the bits of data by blowing small fuses inside the memory device. Once they are programmed they cannot be changed. The term BIPOLAR reflects the transistor technology used in the manufacturing process.

I also checked my programmer and it cannot read these chips, but there is light https://www.youtube.com/watch?v=6oyO7Q_yWLQ i dont have the adapter he has

I have a device that can read and program those chips (TopMax II), but logistics are a problem...

seems there were several chips that also worked:

nation 74S471
TI 28L22