D27512J

[Neon_WA]

picked up a common looking Intel eProm D27512J out of a huge copy machine, but quickly found that the part marking was uncommon.

Also having no speed designation made it even more uncommon

If anyone knows or comes across the information of what the letter J in the part number is for, I would be greatly appreciative

from the other eproms in the unit.. the date code would be week 06 1991
there is no (m) or copyright & no die information on the underside of the chip.

is it a second source marked as Intel?.. as the font is different from other eproms of that vintage

[CPUShack]

here is mine

[6a6ar09a]

One more visible difference. Regular chip (without J) have two layers below die, silver colored and golden. Chip with J have just one layer below die, silver colored (don't know what it is, palladium, platinum ???).

Probably some kind of difference in production process... I have three different 512's. One of them is like yours.

BTW. Printing is somehow bolder too.