pcmhacking.net

Yeah ok. I think I need to do some research on EPROMs/eeprom’s so I know what I’m looking for/at. It’s all mud to me currently

Vr vs v8 manual 256k 27c256 vr vs v8 512k 27c512

I understand that the last three digits denotes the size of the chip and that the 256k is for manuals and the 512k is for the autos but apart from that I’ve got no idea what the “27” means or how to tell if it’s slow or fast “ns” or how to identify a suitable replacement.

27 is the design series, the type of chip basically. The letters on the end might give info on a data sheet. Some even have the speed on the back, usually 90, 100, 120 or 150, some 180

Oh ok so the higher the ns number the slower or faster?

Also group buy anyone?!?!?

data sheet says 200ns. Way too slow, also non industrial temp range. only spec'd to 0c-70c, industrial ones are -40c-85. So if it gets cold enough it may do funny things not that you can use it.

Higher the number the slower it is you want 100ns or lower its the delay from requesting an address and getting the data so lower is faster .you have to watch out though cause some have low numbers after the 27c256-15 etc can mean 150ns they drop the 0. 45 75 or 100 you are safe even 120 can work but they get slower the more times you erase them and program them .I found the speed of the ones linked from the part number ending digits

2 mean 200ns in this case, the JL is normal spec not industrial which is JE

Aaaaaah ok it’s starting to make sense now. I’ve just been googling data sheets and I’m sort of making sense of some of the info. I assume you are referring to the operating temperature and no the storage temperature and does the “ns” stand for nanoseconds? Because that would make sense to me.

yes nanoseconds. The temp specs are operating temps, at least guaranteed specs. Storage temps are a bit arbitrary really.