BBC Master 128: The evolved 8-bit computer from Acorn

Comments · 919

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  @adriansdigitalbasement · 3 years ago · pinned

  George who sent me this machine told me that it was indeed used inside the BBC studios, hence the &quot;brand&quot; on the top cover and stickers on the underside. Also, Pete Sapwell (adn some other folks) commented this on the PSU situation: <br> <br>Hi Adrian, you’re correct about the voltage doubler for the 110V mod on the PSU, the two smithing caps are in series for 240V with the middle unconnected, and if powered on 240V each cap would have 120V across it. When you fit the 110V wire link mains neutral is connected to the centre connection of the caps, the the normal bridge rectifier action charges one on the positive cycle and the other on the negative, again resulting with 110V across each cap and being in series presents 220V to the power supply switcher. :) hope this helps

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  @cowasakiElectronics · 3 years ago

  I was an acorn component level service engineer. Acorn gave out the schematics with the advanced user guide so everyone could see what everything did. Econet was a file system and could be used for loading and saving or printing and acorn sold a server that sat on the network with the other devices. The analogue socket was for analogue joysticks or paddles. Rs423 is TTL RS232 so basically compatible but minus the 10v or whatever 232 was supposed to be. All BBC model A and B computers boards had space and holes for Econet and the disc system but you just had to install the floppy components and a floppy filing system ROM to use it.

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  @timvickerstaff3670 · 3 years ago

  I completed my A Level Design Technology on my schools only BBC Master. A couple of years later my teacher called me to say they were having a clear out and did I want the computer? 30-something years later I still have it.

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  @Zerbey · 3 years ago (edited)

  I owe my entire career to the wonderful BBC Micro, including the BBC Master. &nbsp;I think many IT professionals who grew up in the 1980s and early 1990s do, every school had at least one and they were absolutely fantastic machines.

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  @jimmoores7883 · 3 years ago

  The deal with the battery is that the battery sized slot next to the speaker was originally for a rechargeable 4.5V lithium cell, but there was a mistake with the charging circuit which caused it to catch fire/explode. &nbsp;They quickly swapped it out for the shrink-wrapped three AA duracells down the side of the keyboard and a (rather essential) diode in the pack to stop the charging circuit from pushing current through them. &nbsp;The 1MHz bus wasn&apos;t for slow peripherals, but rather fast ones like a hard drive - they had a larger amount of address space mapped to them than e.g. the user port. &nbsp;The analogue in is for a multi-channel analogue joysticks/crap mouse/experiments.

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  @adriansdigitalbasement · 3 years ago (edited)

  George confirmed that this machine was used at BBC Broadcasting House as part of the studio infrastructure! So, there is some real pedigree here to this particular specimen!<br><br>Also, thanks to many good tips from patrons, I now know how to service the keyboard on this machine. Watch for part 2, coming soon!

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  @tom_123 · 2 years ago

  George was extremely kind to send you such an awesome parcel - a rare computer, a ton of jello and some mugs?! What an amazing guy!

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  @Andrew_Waite_Stuff · 3 years ago (edited)

  A Raspberry Pi CoProcessor kit will upgrade the Beeb to the max. The BBC Micro was originally designed to be a multi processor machine with a TUBE interface to connect external coprocessors. Back in the day 3MHz and 4MHz 6502s, Z80, 68000 and x86 coprocessors were available. The coprocessor ran programs and sent API calls over the TUBE to the host machine. Acorn used this feature to develop the original ARM-1 CPU. Using software adapted from the 1985 vintage ARM Development System the Beeb and Master can be upgraded with a modern ARM on a RaspberryPi. As the Beeb was designed to be a multi processor machine which could be upgraded with faster coprocessors adding the Pi upgrades the machine as Acorn historically intended.

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  @dougall1687 · 3 years ago

  These machines were robust. &nbsp;When I was about 11 I took a meccano motor and added a steering wheel to the front, then connected the outputs into the analogue port and read the analogue voltage from the memory mapped registers to get the rate of turn on the wheel. &nbsp;This let me create a racing car game. &nbsp;I think many other machines would have died during my experiments or killed me, but the BBC micro was a forgiving teacher.

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  @decidedly_retro · 3 years ago

  For the keyboard switches I&apos;ve found Electrolube EML to be excellent. Spray copious amounts down the key stem and operate a few dozen times and even dead keys return to normal.<br><br>DeOxit may work too but I&apos;m not sure it&apos;s reducing agent is quite as strong as EML.

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• KO

  @kodabar · 3 years ago

  The &apos;Network 23&apos; writing is interesting. The BBC Master came out in 1986. In 1985, Max Headroom first appeared - and did so on British television. Yes, Max Headroom appeared in the UK first. Now it wasn&apos;t a BBC production - it was Channel 4 (there were four channels in the UK at that time). In the initial film (the TV series followed a few days later) Edison Carter crashes into a barrier marked &quot;Max. Headroom 2.3 metres&quot; and the TV network he worked for was Network 23. So I have to wonder if the writing is a reference to that. It may simply have been a reference to the machine&apos;s position on the Econet network, but the timing is right.<br><br>I used to have &quot;Welcome to Network 23&quot; as my Windows startup sound as well as various Max Headroom noises for all the other system sounds. I also had Network 23 wallpaper and a screensaver. My friends and I would amuse ourselves making these things.<br><br>I guess we&apos;ll never know if this is a Max Headroom reference, but I&apos;ve never seen any BBC asset tags like that Television Network sticker.

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  @leeshepherd6512 · 3 years ago

  The finest 8 bit machine ever produced IMHO.

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