18 Apr
2007
18 Apr
'07
10:49 p.m.
On 17 Apr 2007 at 19:53, Tony Duell wrote:
Motorola marketed the MC4041 as something very much like this; it was
a pre-programmed version of an XC170 ROM. Of course, they were also
suggesting that the same ROM be used as a BCD-to-7 segment decoder
(MC4039) and a 3-bit-to-8 demux (MC4038). Note that I said "early"
:)
That last oen is totally ridiculous IMHO, given that a ROM contains an
n->2^n decoder to select an a particular location in the ROM determined
by the states of the n address lioes.
And if, as you said, it was early, there's even less of a justification.
Trasnistors were more expensive back then...
-tony
I think
that the early databooks also show how to make a parity
generator from a bipolar ROM.
You can make any combinatorial logic circuit from a ROM. Using one for a
parity tree seems ridiculously over-complex, though.