David Wilson wrote:
On Jun 1, 1:01 pm, Alex Freed <al...@mirrow.com> wrote:But seriously, why do mask-programmed PROMS fail so often?You are confusing two different technologies in that question - PROMs are not mask programmed.
I should have said "mask-programed" ROMs, not PROMS. I just assume the ROMS in mass production were mask-programed. I'm aware of the fuse based PROMS. Even used a few back in the 80s.
From memory: 23xx = ROM = mask programed during manufacture 26xx = PROM = programmed by blowing titanium fuses - these can sometimes grow back 27xx = EPROM = UV erase 28xx = EEPROM = 12V erase 29xx = EEPROM = 5V erase As for why old ROMs fail, I do not know.
-Alex.