I have 15 ST-branded M27C256B UV-erasable EPROMs and a Minipro TL866 chip programmer. The chips came as used off Ebay. When I try to program these chips, I get this:
$ minipro -p "M27C256B @DIP28" -w cleurom2.bin -S Found Minipro TL866A v03.2.80 Chip ID OK: 0x208d Writing Code... OK Reading Code... OK Verification failed at 0x200: 0xc8 != 0x00
I thought that this was due to this particular variation of the 27c256 requiring more current than the Minipro burner could provide. So I bought a cable that has two male USB type A plugs on one end and a female type A jack on the other end. I've used variants of this for older hard drive enclosures that needed the extra current. This didn't help in the slightest. All of them fail programming in exactly the same way. Erasure goes fine. I've programmed several 27c256 chips from Texas Instruments with no problems. What's going on here? Am I better off simply trashing these chips?