[sdiy] Logic Gate help (Help!)

[Donald Tillman]

On Jan 26, 2013, at 10:40 AM, cheater cheater <cheater00 at gmail.com> wrote:

> What I'm asking is whether their use of RTL is an implementation
> detail that might be executed differently nowadays (CMOS, FPGA), or if
> it simply is the best way to do what they are doing, even today.


Fine question.  Does anybody know what year the Moog 960 came out?  It may have been the first Moog module to use IC's.

You can get a feel for the technology of the time by going back through old issues of Popular Electronics Magazine.  Here's one source, I'm sure there are better ones:

   http://www.swtpc.com/mholley/PopularElectronics/Popular_Electronics.htm

If the Moog 960 was designed around 1969, the available logic families were probably RTL, ECL, DTL, TTL, and Signetics' "Utilogic" (there's a blast from the past).  The last three were pretty much the same, and certainly compatible.  And, of course, individual diodes and transistors.

RTL was very well suited for this:
   * inexpensive
   * more functions available
   * handled a wide range of supply voltages
   * well behaved
   * you could wire-NOR the outputs
   * interfaced to linear circuitry nicely
   * could be biased into linear mode with a resistor

So RTL is the most like CMOS, but still different.  I'm sure the Moog 960 took advantage of some of those features, so a blind substitution probably wouldn't work.

I built my first sequencer in 1971 when I was 14 years old (I think), so I remember these issues well.

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com