using new technology on old machines. Was: PDP-12 Restoration at the RICM

[tony duell]

> >
> > Unfortunately I believe you. Use at least a thousand times more components than
> > you need to.
> 
> Actually it's just two, a Teensy and a usb cable. (Sorry, I couldn't
> resist).

I am of course counting all the transistors inside that chip.

> How do you suggest I learn? I believe you had a father that got you of
> to a good start and perhaps you even took a few classes.

My father was a chemist. He knew enough electronics to teach me things
like ohm's law, but certainly not digital electronics. And I have never done
any classes in electronics.

I learnt by : 

1) Reading every darn book I could find on electronics from the 1920s onwards

2) Experimenting. Soldering up circuits and finding out why they didn't work. Some
of the better educational kits like the Philips EE series helped in my younger days,
but alas you won't find those now.

3)Getting a minicomputer and investigating it. That means reading the printset, cliping
on a logic analyser, etc. 

> Certainly no excuse, but one of the main reasons I'm in this hobby is to
> learn! And boy have I learned a lot since I got started. I'm not at your

As am I. I've learnt a heck of a lot since I started (there is a common myth
that there is something magic about a processor. This hobby has taught
me to understand quite a few at the gate level). And the day I stop learning
is the day I am in a pine box.

> level yet.. but perhaps in a few years I'll be a tenth of the way there :)

> It might please you to hear that the Teensy I'm talking about is in a
> socket on a perfboard together with a handfull of 74165 and 74374 which
> I've wirewrapped in proper wirewrapping sockets. It will become a USB
> interface for my 11/70 front panel. The Teensy was the simplest/cheapest
> way to get a usb interface with lots of I/O pins. (Why usb? to get a
> connection to simh on one of those newfangled Pi-things)

As an aside, I am not overly enamoured by the RPi. I think there are 
possibly better alternatives like the Beagleboards (?) which I need to
investigte.

This is one of my main dislikes with USB. It is so complicated that you 
have to use a microcontroller. Unlike any of the more sane interfaces that
you can implement with simple logic if you want to.

-tony