24 Feb
2013
24 Feb
'13
12:01 p.m.
so what is the difference between a mask ROM 8048 and an 8748
The 8048 with mask ROM is programemd when the IC is made. In fact the ROM
contents are determiend my one of the masked used in making the IC. So
it's only practical to have that doen if you are buying many thousands of
them with the same program in them.
The 8748 has an intenral EPROM for the program store. It can be programed
'in the field' using a special EPROM programmer (it's not the same as a
noram lEPROM, but the princple is the same). You can program 1-offs.
Cerainy some 8748s ahve quartz windows over the die, so you can erase
them. The downside is that he data retention time of an EPROM is probaly
less than the life of a mask ROM.
-tony