Home Page Forums MAME MAME Can TL866 check id hurt a mask rom?

Hardware noob question:


I was reading a datasheet for the 27128 and it said that identifying a chip will put 11.5V on pin a9. If I'm trying to read a rom that's just a regular rom (non-eprom) will that hurt it?

on the TL866 options there's a "check id" that defaults to being set.


Electronic Signature
The Electronic Signature mode allows the reading
out of a binary code from an EPROM that will
identify its manufacturer and type. This mode is
intended for use by programming equipment to
automatically match the device to be programmed
with its corresponding programming algorithm.
This mode is functional in the25°C ± 5°C ambient
temperature range that is required when program-
ming the M27128A.
To activate this mode, the programming equipment
must force 11.5V to 12.5V on address line A9 of the
M27128A.

A lot of mask ROMs do not have the ID feature, so their A9 pin is not 12V tolerant. Does the mask ROM not have any indicators identifying itself?

Sometimes the chips have markings that don't tell you exactly what it is or a label covers it up. This one chip recently I wanted to verify that it was a 2764 but after destroying the label there was no markings underneath. Just tell me what it is, what it really really is.

I think I'm just gonna be careful to uncheck that "check id" box when I do a read.


I swear, bent pins are the worst thing ever. Seems like every time I pull a chip I bend the pins around. Nothing a pair of tweezers can't fix, but it's so aggravating.