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English Invader

BBC Micro for Dummies

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I'm thinking of doing something insane and buying another vintage computer system in today's grossly inflated market.  The object of my attention is the BBC Micro; a system I haven't had much to do with since primary school and haven't managed to find a satisfactory emulator for.

 

I've ascertained that the best one to go for is a model B because it has 32k memory and RGB-Scart and that an SD card interface is the best option for software.  The go-to solution has a ROM chip that goes into one of the sockets on the motherboard and the SD card reader goes in the system's user port.  I've also noticed that the system's weak point is the internal PSU with capacitors that will need replacing.  Are there any alternative, after-market PSUs for the Beeb and, if so, how good are they?  I'm also led to understand that the Beeb has a heatsink on the motherboard.  Is that worth replacing or refitting after 40 years?

 

I've looked into the possibilities of either buying a refurb system with the work all done or buying a fixer-upper and doing the work myself.  Having looked at the cost of the PSU capacitor kits (a couple of quid on eBay) and the SD interface (about £20), I can't help but feel the £200-£350 refurb sellers are asking is unjustified so it may be time for me to learn how to solder.

 

I also wanted to ask about the co-processor port and how some people have used a Raspberry Pi to emulate a 300MHz processor.  This is an uncommon feature for the 8-Bit micros and I'm curious as to what the benefits are and what software is available to take advantage of it.

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Posted (edited)

I once replaced capacitors on a Beeb. Then another one had a broken RIFA which I tried to replace, somehow swapped the wires wrong and blew the PSU. Instead of trying to repair it, I replaced it with a Meanwell (*) PT-65A (or is it PT-65B?) which fits very nicely inside and has the right voltages. I can't recall any heatsink on the motherboard.

 

I once tried to build the mmbeeb MMC interface but didn't get it to work so I bought an IDE interface from Retro-Clinic and use it with a CF adapter. I understand there are a bunch of options, also including the GoMMC.

 

I don't know which other repair or improvements the sellers asking £200+ have done, but like I mentioned in the ZX Spectrum thread, people most likely want to get paid for their work, in particular in a market with steadily increasing prices (up until the point the economy crashes, though for some reason it doesn't seem to happen any time soon).

 

I know about the co-pros but never investigated using it or for which purposes you'd want it other than showing off a cool feature. The same probably goes for Econet, which according to some sources even Bill Gates got impressed about when he first saw it.

 

(*) Those are not super cheap normally, but for some unknown reason Elfa in Sweden had a massive sale on those a number of years ago. I bought three power supplies at the time since those were so cheap. I think they increased the price again, not removed it from their inventory...

Edited by carlsson
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I'm now the proud owner of a model B BBC Micro.  I posted on the Stardot forum and they helped me find one at a good price (£102 including shipping) and put me in touch with someone who recapps the BBC power supplies.

 

Thank you for your help.

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Stardot is a great place to get help with the Beeb and the Beeb is a really good and sometimes underappreciated micro. 

On 8/18/2020 at 9:08 AM, English Invader said:

I also wanted to ask about the co-processor port and how some people have used a Raspberry Pi to emulate a 300MHz processor.  This is an uncommon feature for the 8-Bit micros and I'm curious as to what the benefits are and what software is available to take advantage of it.

You will need a cheap interface to fix the voltage difference between the Beeb's Tube port and the Raspberry Pi (leveler).

 

You can pick them up on eBay for like £12. Search for RetroClinic, That guy does a bunch of Beeb addons and I've brought from him plenty of times.

 

Cheapest solution and best bang for your £ is to get a Pi Zero with headers soldered for about £12 (unless you are happy to solder the headers yourself, in which case a PiZero is like £5)

 

You then need to download the PiTube software, pop it on an SD card and put that in the PI. Plug the Pi into your beeb and you are pretty much good to go.

 

What you can do with your BBC + Pi CoPro depends on what you have attached to your Beeb to load up software. A gotek or SD card solution would be recommended as a minimum.  I have an internal Datacentre interface which provides me with USB (for a USB stick to load on disk images, bit like a gotek) and a CF card that acts has an old style BBC Winchester Disk (HD).

 

The PiTube CoPro can operate in different co-processor modes from simple 3Mhz 6502 (like an old style BITD BBC CoPro) or a full speed 6502 roughly equivalent to 280Mhz on a Pi Zero. This lets you run the Executive version of BBC Elite & Basic flies. I ran some Mandelbrot calculations that took 4 hours unaccelerated, with the CoPro 6502 full speed, they took about 2 minutes.

 

Or you can fire it up as a Z80 and run CP/M. Maybe you fancy running as a 80286 and running GEM or DOS. You can also run 6809 or as an ARM2.

 

You can run the Co-Pro as a native ARM1176 1Ghz. I've run Doom via the BBC in this mode with the Beeb handing off the calculations to the ARM co-pro but running the GFX & input through the Beeb. I've been testing a working version of Frontier Elite 2 as well which runs probably slightly quicker than an 68000 ST version on the Beeb.

 

More info here about the PiTube CoPro https://www.sundby.com/index.php/pitubedirect-manual/

 

Also lots of help on PiTube on startdot, 

 

 

 

 

 

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