hardware parity generation

[Tony Duell]

> 
> On 17 Apr 2007 at 19:53, Tony Duell wrote:
> 
> > > 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.
> 
> 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