Date   : Fri, 12 Jan 2001 18:36:39 +0000
From   : Ben Newsam <ben@...>
Subject: Re: Emulation, long term preservation and Domesday

In message <3A5EDACC.81C530F2@...>, Paul Wheatley
<p.r.wheatley@...> writes
>We've not really examined the peripherals issue in great detail although I
>have to agree that it is rather important. I think primarily you want to
>emulate peripherals at as high a level as is possible in relation to your
>platform emulator.

Of course, if the emulation is complete, then it should be possible to
emulate all the possible peripheral devices. For instance, a hard disk
attached to the 1 MHz bus on the BBC Master.

> Most peripherals have little historical value in
>themselves from our point view, and the requirement is simply to preserve
>their functionality required by software you want to run on your main
>emulator.

When controlling external physical stuff, it is difficult to envision
how such things *can* be emulated. I have written software to interact
with bespoke input and output devices, and to control VHS and Sony
Umatic video recorders[1] via specialised interfaces (usually through
the 1 MHz bus), as well as the more usual "simple" interfacing through
the Use, Printer, and Analogue ports.

>The case of the buggy is an interesting one. Is it something we can actually
>realistically preserve for the long term?

It was built of fischertechnik, and so it should be preservable
physically. There would be a wear issue with the chains and tyres
though, I am sure. The biggest problem would be the eventual breakdown
of the electronics, either the circuit boards or the stepper motors. The
specific Fischertechnik parts are almost certainly no longer
manufactured in the required form.

I no longer possess a complete Buggy, but I do have a full set of all
the electronics[2], which I have set up as a test rig.


[1] One of my machines has a genlock board on it, although the results
were poor, to say the least. We ended up not bothering, switching the
whole screen to video and back and not worrying about the timing.

[2] "Interface" board[3], main board, and Grab Arm[4] add-on board.

[3] Separate boards were produced for BBC and RM computers. One (and
only one) PC board was produced as an experiment.

[4] A useful little board, controlling two DC motors with a measurement
of motor current fed back into the analogue channels.
-- 
Ben