TTL HEX LED driver chip

Tony Duell ard at
Thu Oct 28 14:07:32 CDT 2010

> As a pure ROM, you may be thinking of the MC4039, which, by 
> Motorola's admission, was nothing but a preprogrammed version of the 
> XC170 128-bit mask ROM.  Circa 1969.

If you ingnroe 'progammable' devices (PROMs, PALs, FPGAs, etc), what's 
the simplest solution for getting 0-9,A-F from 4 bits of binary using 
only 74xxx devices (and preferably common ones). I can trivially do it 
in 7 such chips, but alas they're all 24 pin devices. Anything simpler?

> The same ROM was used as the MC4001 BCD-to-Binary/Binary-to-BCD 
> encoder.

I beleive the 74184/74185 BCD<->binary converters were programmed 
ROM/PROMs too. And as an aside, there were some MMI logic chips, things 
like counters with extra facilities, which were clearly programmed PALs/HALs.


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