OT: learner kits (was: Re: using new technology on old machines)

[Dave G4UGM]

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mouse
> Sent: 20 June 2015 13:54
> To: cctalk at classiccmp.org
> Subject: Re: OT: learner kits (was: Re: using new technology on old
machines)
> 
> > 	Is there a reason to prefer 7400 series over CD4000 series logic?
> 
> If you can find real TTL, yes, I would say so.  It's less static-sensitive
and it's
> more tolerant to things like hooking two outputs together by mistake.

The pack recently mentioned was, I think 74LSxx TTL which is probably the
most common and should in most cases be capable of replacing standard TTL.
The other advantage of TTL is that is quicker. On the other hand CMOS is
more tolerant of supply voltage.

> 
> But note that there are many chips that have more or less TTL interfaces
(TTL
> voltages, TTLish numbers, and in some cases switching
> thresholds) but are actually CMOS - the 74ALS series comes to mind.
> 
> Of course, if someone somehow builds CMOS chips with TTL's ESD tolerance,
> short-circuit tolerance, etc, then great.  But that's not what I've seen.

Most modern CMOS is "BE" series and so have ESD protection.

> 
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