On 1 Oct 2008 at 17:38, Roy J. Tellason wrote:
Whoops, you're right, that's exactly what I
was thinking of, though I'm
pretty sure I was also remembering Motorola...
Perhaps one of those two companies was second-sourcing the other.
All of my databooks are currently in boxes, and I'm not even sure which ones
are in what boxes, a situation that I'm hoping to correct somtime soon, so
I can't verify my recollection on this.
Okay, I dug out my Moto databook. Yes, Moto had a 7-segment decoder
that was derived from the XC170 ROM and labeled MC4039 (MTTL not
MRTL). Other notable MTTL circuits from the same memory array were
the MC4038 1-of-8 demux, the MC4040 2-of-8 decoder and the MC4041
Hamming code generator/detector.
On the subject of ganging these things, appnote AN446 has some
interesting examples. A binary to 1-of-64 decoder using 9 of the
ROMS, for example. But the most relevant is a circuit for driving a
16-segment alphanumeric display using 5 ROMs driven from 6 bits.
Cheers,
Chuck