The MC789 is a hex inverter, a 7404 or 7406 could be used but the pin-out is
different :(
There are two simple solutions: an adapter or a foil change.
With an adapter you are able to keep looking for the right part. With a
foil change it looks better.
Randy
----- Original Message -----
From: "Cini, Richard" <RCini_at_congressfinancial.com>
To: "'General Discussion: On-Topic and Off-Topic Posts'"
<cctalk_at_classiccmp.org>
Sent: Friday, January 07, 2005 7:41 AM
Subject: RE: RTL Logic
> OK, this might sound like a stupid question, but being somewhat ignorant
> of
> RTL logic in comparison to TTL and other designs, what, if anything, can
> be
> substituted for RTL logic chips?
>
> For example, if I wanted to build one of Don's devices and I wasn't
> concerned with using "vintage" chips, could I do it "plug-and-play" using
> current TTL?
>
> Rich
>
> -----Original Message-----
> From: cctalk-bounces_at_classiccmp.org
> [mailto:cctalk-bounces_at_classiccmp.org]On Behalf Of Michael Holley
> Sent: Friday, January 07, 2005 12:08 AM
> To: cctalk_at_classiccmp.org
> Subject: RTL Logic
>
>
> I have acquired some Don Lancaster designs that use RTL logic and I am
> looking for spare parts. The MC789 hex inverter is used in all of them and
> I
> have 2 chips. Does anyone have a reasonable source for the MC789, I can
> get
> all I want for $20 a chip.
>
> I also have 2 MC799 buffers that are use in the Microlab. I have found two
> each of these (MC725, MC778, MC785, MC792, MC853, MC855) that I will part
> with.
>
> SWTPC Digital Logic Microlab
> http://www.swtpc.com/mholley/PopularElectronics/Apr1970/PE_Apr1970.htm
> Early SWTPC keyboard
> http://www.swtpc.com/mholley/PopularElectronics/Apr1974/PE_Apr1974.htm
>
> I think that Don Lancaster's TIC TAC TOE machine from 1971 is a very
> clever
> design. It uses 5 ICs and 60 diodes to play the game. I may build one.
> http://www.swtpc.com/mholley/RadioElectronics/Dec1971/RE_Dec1971.htm
>
> Michael Holley
> www.swtpc.com/mholley
>
>
>
>
Received on Fri Jan 07 2005 - 10:56:39 GMT