13 Sep
1999
13 Sep
'99
8:11 a.m.
Tony wrote about HP part numbers:
Alas ROM and RAMs both had 1818-numbers.
Actually, RAM chips were usually only 1818 if there was some unique
characteristic, such as a hard-wired address decode. General-purpose
RAM chips were usually 1820.
In the calculators, sometimes RAM had make-programmed address decode,
and sometimes it was combined with ROM or other functions.