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While waiting for a Master expert to chime in... Teletext chips don't fail often but sockets do. Have you tried cleaning/reseating any socketed chips? (My Master has very few most chips are soldered directly... but worth a try).

I use itzor's gcc port (latest is gcc8). It kinda needs some backend work to be truely useful as the pointer dereferencing in particular produces some terribly clunky code. He hasn't touched the repo on githhub for a couple of years now though :( I have looked at the backend but they are flipping co...

I've seen a hairline fracture in one of the -5v tracks on one PSU before now. If you have the same model PSU the -5v track runs very close to one of the screw holes... I had a crack propogate from the screw hole (overtightened by soemone probably) through the PCB and copper. Very hard to spot.

There are more good interviews with experts on Robert Feranec's electronics/PCB channel.

Splitting ground planes
Crosstalk

Doing it this way would avoid the need for the load-to-RAM. And I bet Chris Morley could get it on a very small board with reprogrammability? - Chris . . . ? It would be possible to do a board with an surface mount EEPROM on the top (like my 64KB EEPROM module) and 32KB SRAM + 22V10 PLD on the bott...

The JMP will assemble with an absolute address. When you run the second program the memory allocated by the DIM is unlikely to be at the exact same absolute address. If you reload the code at the wrong address then all absolute instructions still point to their original absolute position... which is...

The limit has been removed by the UK. The €15 limit is due to be removed by the EU.

It is easy to edit the keyword list. You could add the assembler tokens too pretty quickly.

https://www.ebay.co.uk/itm/Vintage-Comp ... Swbd5ekgs1

The £599 model B is back now with a "cash only" request in the description.

edit: they have the same thing listed three times...

Ah, so for £40 for a couple of BooBip modules, any model B can have a nice big RAM space for games to work with. Excellent! (That's only 10% extra on the machine price, in round numbers) A bit less £ than that but yes... Another thing worthy of note is you can also replace the CPU vectors (reset, I...

Yes with the OS RAM + 1 bank of sideways RAM you can have 79KB of RAM in use without changing any paging registers (or 63KB if you keep the OS paged in for code) - on a otherwise standard model B.

£599 for a model B anyone? oh plus £30.30 (not a typo) economy delivery...

https://www.ebay.co.uk/itm/Acorn-BBC-Co ... Swbd5ekgs1

Relo wrote: ↑

Sat Jan 02, 2021 2:05 am

Paying VAT isn't much of issue, I know that anything below 45 euro won't get taxed if I trust the government page (last year was 25).

Everything is available though this forum even if it I never return to eBay. I have some threads in the buy/sell forum.

from BooBip ... (though he doesn't seem to ship to the Netherlands ATM, probably due to brexit) Aside from the Gotek are there any other recommended storage solutions? I remove all my stuff from eBay around Christmas every year. I get a few item not arrived cases opened against me each year with pe...

I only know of one game that supports the WE shadow RAM, assuming that is what it is and that is my Astro Blaster, but there are probably others. I think its main use was as a printer buffer, but again I could be wrong. I think some adventure games can use it for reduced loading/increased graphics....

If it is damp the machines will corrode & might stop working eventually. If it is dry then shouldn't be a problem.

Hot/cold cycling is only really bad if there is humidity/moisture as it promotes condensation and corrosion.

Would soft keys work for you? Program the soft key in the !BOOT & invoke.

I use this one I found on the internet years ago. I can't remember the original credit.

Becky wrote: ↑

Sat Dec 26, 2020 9:37 am

I suppose it would make sense to use the more advanced machine.

The bigger keyboard on the Master makes it an excellent source for replacement keyswitches when repairing Electrons

So from that I can confirm that bit 7 is faulty in CAS0....My deduction therefore leads me to believe that IC68 is the culprit....am i right? Your logic seems sound. Inverter connected so 0x4nnn is CAS0. Bit 7 -> 0 at some locations. Bit 7 CAS0 is IC68 as you say. edit: This also lines up with RR's...

I don't understand why you are using arrays. Why aren't you using normal n bit registers?

reg [7:0] a;
reg b [0:7];

a is an 8-bit vector
b is an array of 1 bit vectors

They are not the same thing and not interchangable AFIK.

indeed...
reg [15:0] c [0:3];

would be a 4x 16bit array.

If it has an EEPROM/FLASH for storing the config these do wear out.... could be that. Can be a problem on older car stereos apparently with them turning on at full volume (because they forgot the last setting). You could try opening it and seeing what is inside... or you can live with it... or you c...

mr.spiv wrote: ↑

Sun Dec 20, 2020 9:43 pm

1) Bit 5 ($20) is always cleared between $4000-$7fff in MODEs 0 to 6. Is this IC66 then, which is broken?

Sounds about right.

Ahh, the weird video smearing could well be the UHF...

Not sure what you mean by 33-bit frequency; the sound chip uses 10-bit pitch IDs internally, which are looked up from the b-tracker note number by a table. I assumed Richard was talking about the total bits to program the sound chip VGM style... 3x10bit (tones freq) + 2bit (prng freq) + 1bit (perio...

Those screenshots do look weird. You might well have 2 faults, a RAM fault + a video fault :/

FWIW, it seems that *EXEC uses 1100 and 1200, so while loading files there works fine in bench testing, trying to load from a !boot script causes weird errors and corruption (including disk errors!). I think that is why people put CLOSE #0 in their !BOOT file - to close the *EXEC file handle. e.g. ...

We'd need to believe the duplicator's drive has surprising precision for 1985, but the PDF linked above does bang on and on about quality. Why are you surprised that something precision could be engineered in 1985 in a money no object commercial/industrial device? Take a look at some eevblog vintag...

Back.. I finally got the SN74LS04N and made the fancy address inverter to S25. The machine boots up in 32K mode - hooray! However, there's still weird stuff ongoing. The inverter has not fixed anything, it just adds evidence that you have a RAM fault in the bank which is now mapped to 4000-7fff (us...

1024MAK wrote: ↑

Tue Dec 15, 2020 3:35 pm

PS I still think trying to solder up mini DIN connectors is the hardest, as the plastic melts as soon as you think about picking up the iron...

Mate the din connector. The added thermal mass of the mating half reduces plastic melt but also helps keep the pins in the right place if it does melt.