When looking at his feedback I see many people complaining about fake items so I guess the joke is on me for not checking the feedback before buying.Īnyway, I figured I should give you all a heads-up so no one else wastes time and money on this crap.Note: if you come here and stock is 0, put yourself on waitlist - I re-stock (especially the assembled versions) once I have a few orders on waitlist.ĮPROM Emulator is a tool that can temporarily replace an EPROM memory chip inside your 'target' device. I requested and got a refund from the seller but the listing is still up so he doesn't seem to be overly concerned about selling useless counterfeits. After a bit of googling I found this site and it turns out they are all fake. Then I tried them in my programmer (a MiniPro TL866A) and the software reports that the selected chip doesn't match the ChipID read from the ROMs (the ID is DA 02 and I can't find out what type of ROM that is supposed to be). No biggie though, I figured - I have a pair of needle-nose pliers and lots of patience.

The package arrived some time ago and even though the listing claims that the ROMs are new they were kind of dirty and had scratches plus a lot of bent pins. I bought 10 of these from this listing because the data sheet says that they are drop-in replacements for 27Cxxx ROMs so my plan was to use them to host XTIDE Universal BIOS on NICs with ROM sockets. Note: To program the 28cxx or 29cxx I can use a modern programmer, so when I say 'alternative' or 'replacement' I mean for read-only operation (the network card will just read the chip, it will not try to program it). Has anybody tried this, or found a different alternative? So I suppose the best replacement for a 27cxx is a 29cxx, probably leaving pin 1 unconnected. On the 28cxx the write enable pin levels are the same as in the 29cxx, but in addition it swaps pins 1 and 27. Also, it needs a higher voltage on the old 27cxx. This is the write enable pin, which is active high for the 27cxx and active low for the 29cxx. The 29cxx turned out to have the most similar pinout, with only pin 1 different.

I have taken a look at the 27cxx (UV EPROM) chips datasheets and compared to the 28cxx (EEPROM) and 29cxx (flash) ones. I suppose UV EPROMs can be acquired some way, but I have not an UV eraser, and I don't want to buy or make one, because it is a very slow method and I will need to make many erase/burn tries. The socket is a DIP 28, so I suppose it refers to 27c64, 27c128 and 27c256 chips. The card is a 3Com 3c509b, and the manual mentions that 8, 16 and 32 Kb EPROMs can be used, but does not specify which chip models. The PC will not be on any network, but it is an ISA card which I can plug in the PC and the card has a socket for a PROM. The idea is to burn an EEPROM with a programmer, and to use the chip in a network ISA card. I would like to write a ROM BIOS extension for an old PC.

27c256 eprom programmer