using new technology on old machines

Dave G4UGM dave.g4ugm at
Tue Jun 16 10:01:41 CDT 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of tony
> Sent: 16 June 2015 14:55
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: RE: using new technology on old machines
> > Sure, the pre-manufactured boards can allow you to prototype
> > quickly... but I think Tony is kind of bemoaning the loss of the "old
> > way" and I respect that ... I kind of miss it myself, even though I
> > wasn't there to experience it first-hand ...
> It's also that this is the 'classic computers' list. To me, classic
computing means
> rather more than just the hardware. It also covers the design and
> construction methods, technology and so on. And there seems to be
> precious little of that in a modern microcontroller acting as a clock

There isn't., but some-times we have to compromise, and sometimes we choose
to compromise. I looked at the circuit of the M484 and I might not have the
parts in the parts box...
.. its also a nasty hybrid design with DC biased NPN and PNP transistors. I
find it ugly and can see it being a pig to debug, though it simulates fine
in LTspice...

> I find it odd that people want to have a lights-and-switches panel, but
> prepared to totally adulterate the hardware of the machine that drives it.

There sometimes isn't enough hardware to go round. I would like a front
panel for my SBC6120 but I don't think DEC built a machine with a 61xx chip
and a front panel...

> As an aside, when I restore m 11/730 I am in 2 minds as to what to do
> the microcode load device. a TU58 emulator is certainly convenient, but I
> actually would rather get the real tape drives working if at all possible.
> all that is what the machine was designed to use.

Nice if you can get it to work.

> > How are everyone's parts bins so empty? My dad is a practicing EE of
> > over
> Mine isn't, but then you knew that, right :-). When I moved house recently
> think I had over 30 packing boxes of modern-ish components and more of
> valves and CRTs. Not counting the dozen or so boxes of PCBs (some to use,
> some to raid for parts).

I have a good selection of TTL but I am not longer sure if it works. I think
a lot of NOS TTL has rotted internal connecting wire. 

> -tony


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