Acorn System 1

[SiriusHardware]

It seems strange to say it but the fact that you still have the original cardboard box with Acorn labels will add significantly more value to an already valuable item. Good to see that it still powers up, too.

[Alan Bain]

Strangely that's just the box it lived in and I realised fairly recently it was the box the kit was posted in. Old computers need to work or they are just paperweights in my book!

Alan

[SiriusHardware]

Of course, you are preaching to the converted here - but you would be amazed how much that bit of pulped tree would be likely to add to the overall value, especially as the Acorn 'frank' is legible - does it even have a readable date of posting on it as well?

It all adds to the 'provenance' of the machine.

[agardiner]

OK, a little update as a couple of people asked earlier on about the actual usage of the item. I have now been playing with it for the last week or two, following the original manual.

So - the bad first. The manual is not great and is full of little mistakes. Although this is not ideal, it has not really been too much of a problem, it has just meant re-reading sections to understand it better, and going back over previous sections as you progress. (Perhaps it is just me!)

The good. I am having a lot of fun with the computer, way more that I expected. I have never previously dabbled with raw machine code entered in hex; only ever played with BASIC. Given the inevitable limitations and the fact that the manual is only really an introduction so you can understand it better, I am really enjoying the learning process, and have various ideas forming of programmes to try and write as I progress. It has sparked a new interest in vintage micros and has sent my hobby off down new directions. The quality of the recreation is really good and the item itself fun and practical to use. The 6502, despite being a super popular microprocessor, does have some interesting quirks that you have to learn.

So in summary; anyone thinking of trying out this kind of device, or thinking they might like to explore an actual microprocessor, I would say give it a go! And you can do a lot worse I think than an Acorn System 1. Plenty of bits still available to be able to construct one, lots of information about and of course it can be very expandable.

[SiriusHardware]

Glad to hear you are enjoying it - it sounds like the ACS1 manual is much of a muchness with the MK14 manual - not exactly perfect, but OK to stumble your way through. I suppose you are at least getting the same authentic experience as those who built their kit and worked their way through the manual more than 40 years ago.

As with the MK14 manual, it could really do with a bunch of current enthusiasts getting together to edit / write the manual the machine always should have had - but there wouldn't be any money it it, so it would have to be out of pure love, I think.

[ChrisOddy]

For anybody interested in obtaining an Acorn System 1 have a look at my 'System 1 Trainer' project https://theoddys.com/acorn/replica_boards/system_1_trainer/system_1_trainer.html

[SiriusHardware]

That's a lovely looking thing - part of me wishes you had at least provided a position for a second 8154 to go into but still, very nice.

[Chris55000]

Does the Acorn Electron Computer System (I bought a boxed one with accessories !) have the correct interface to be able to suit the Tesla EPROM Blower PCB from Chris Oddy's Shop or do I need to construct something else?

Chris Williams

[SiriusHardware]

Not quite the answer to your question but if you look at the thread about Chris Oddy's Tesla specific version of the Acorn system PROM programmer

https://www.vintage-radio.net/forum/showthread.php?t=193513

...and make your way all the way down to post #102 onwards - especially post #107, you will see a contribution from forum member Realtime which marries a common Arduino micro board to one of Chris's Tesla PROM programmer PCBs, providing a way to program these PROMs without necessarily needing a pre-existing retro-computer system to do it.

[Chris55000]

. . .I shall certainly look at that, as an Arduino based solution would be much cheaper and easier than building it purchasing Acorn compatible hardware!

Chris Williams

[SiriusHardware]

Genuine Arduino Mega 2560s are quite expensive now (£40+?) but there are numerous third party Arduino Mega clones (for example, 'Elegoo') which come in at under £20 and should be fine for this purpose.

I looked at the circuit diagram for the Electron and in theory the connections you would need for the PROM programmer board are there - you might have to derive the high voltage supply from somewhere else, or you can maybe get it by rectifying and regulating the 18VAC which appears to be available at the expansion connector.

Even with all of the hardware connections correctly made, address decoder correctly configured and so on there would still be the question of whether the companion PROM programmer software, written for the system n?, would be able to run on the Electron without modification for that system.

[agardiner]

As I progress with this, I will want to be able to save and reload programmes using the cassette interface. Does anyone know if a microcassette recorder would be suitable for such a purpose for this machine? Or a Dictaphone?

There are many examples online of people who have failed with old computers, with anything other than a standard cassette recorder.

Thanks.

[SiriusHardware]

I can't speak personally for the devices you are asking about although can't see why a micro cassette recorder would not work as long as it has sockets for mic-in and ear/speaker out.

I've had reasonable success using an old Windows XP netbook, using either the native windows 'Sound Recorder' utility or 3rd party record / replay software like 'Audacity' to record and save and reload and replay the audio stream for machines like the ZX81, etc, in effect using the computer as a 'cassette recorder emulator'.

I would only advise that if you use a stereo recorder or other stereo device for this purpose, arrange your wiring so that only one channel of the audio output on the recording device is utilised on replay, don't short the left and right channels together.

I would expect that a microcassette recorder would be mono, so probably ideal if it has the right connections.

[TonyDuell]

I would suggest using a microcassette machine rather than a minicassette unit. The former has a capstan/pinch roller drive and should give a more stable speed than the latter which is reel-drive only.

Other than that I see no reason why it won't work. I remember one of the user manuals for a pocket computer (probably Sharp, but may have been Casio) said you could use an 'open reel', cassette, or microcassette recorder with said machine's cassette interface.

[I do have a moral obection to using many of orders of magnitude more components in the 'cassette recorder emulator' than in the rest of the machine, though.]

[agardiner]

Thanks both - will add one to my shopping list and give it a go. TonyDuell - you have reminded me that indeed a few of the pocket computers of the 80s had docking stations with integrated micro cassette units, so yes, in theory it should be fine. As I understand it, most 80s micros which used cassettes for storage, the System 1 included, use a 1KHz tone to represent '0' and approx a 2KHz tone for '1'. I figured the primary difference in this case for of a micro cassette vs a compact cassette is the overall bandwidth; topping out at about 8KHz for micro.

Point taken and agreed on microcassette vs mini. And I think I am correct in saying that microcassette units use an integrated record/playback/erase head, meaning they will have proper AC erase, unlike many shoebox style cassette recorders with their permanent magnets.

[SiriusHardware]

[I do have a moral obection to using many of orders of magnitude more components in the 'cassette recorder emulator' than in the rest of the machine, though.]

Grudging use of a modern digital device as a recorder / player does have at least one order of merit, which is that any audio stream recorded by it can then be saved in file form such as .WAV and then very easily backed up to multiple locations including the internet or cloud.

It would not surprise me if there is already a PC utility which can read in a .bin or .hex file and translate it into the audio output stream expected by the System 1's cassette interface.

Used in conjunction with a PC based cross assembler for 6502, that would amount to you having quite a nice development system for the System 1 without your ever having to type the code in manually.

[Mark1960]

The Phillips MDCR01 used the minicassette, but as far as I can remember the clock was coded with the data so would be less susceptible to speed variation. I still have a copy of the documents somewhere, and my handwritten and assembled z80 code, but unfortunately not the MDCR01.

[ChrisOddy]

Originally Posted by SiriusHardware

It would not surprise me if there is already a PC utility which can read in a .bin or .hex file and translate it into the audio output stream expected by the System 1's cassette interface.

https://theoddys.com/acorn/acorn_system_computers/system_1/s...ications/system_1_applications.html

[SiriusHardware]

A nice collection Chris - I missed it at first, but I see you've written a Python utility (bin2wav.py) which does indeed create equivalent 'cassette audio' files from code files.