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by cmorley
Mon Jan 25, 2021 3:30 pm
Forum: 8-bit acorn hardware
Topic: Problem with Master 128
Replies: 7
Views: 244

Re: Problem with Master 128

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).
by cmorley
Sat Jan 23, 2021 12:46 pm
Forum: programming
Topic: C compiler
Replies: 4
Views: 186

Re: C compiler

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...
by cmorley
Sat Jan 23, 2021 9:13 am
Forum: 8-bit acorn hardware
Topic: No -5v after recap
Replies: 25
Views: 881

Re: No -5v after recap

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.
by cmorley
Thu Jan 21, 2021 1:57 pm
Forum: general
Topic: Remarkable videos recently posted on Youtube
Replies: 370
Views: 60642

Re: Remarkable videos recently posted on Youtube

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

Splitting ground planes
Crosstalk
by cmorley
Tue Jan 19, 2021 9:04 am
Forum: 8-bit acorn hardware
Topic: B+ DFS & ADFS versions for PAGE E00
Replies: 10
Views: 818

Re: B+ DFS & ADFS versions for PAGE E00

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...
by cmorley
Thu Jan 14, 2021 4:28 pm
Forum: programming
Topic: assembler noob
Replies: 17
Views: 332

Re: assembler noob

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...
by cmorley
Sun Jan 10, 2021 12:14 pm
Forum: off-topic
Topic: Aliexpress VAT
Replies: 14
Views: 386

Re: Aliexpress VAT

The limit has been removed by the UK. The €15 limit is due to be removed by the EU.
by cmorley
Sat Jan 09, 2021 10:32 pm
Forum: programming
Topic: Notepad++ with BBC Basic?
Replies: 9
Views: 416

Re: Notepad++ with BBC Basic?

It is easy to edit the keyword list. You could add the assembler tokens too pretty quickly.
by cmorley
Sat Jan 09, 2021 7:22 am
Forum: off-topic
Topic: LOLPRICE
Replies: 3059
Views: 379743

Re: LOLPRICE

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...
by cmorley
Fri Jan 08, 2021 5:46 pm
Forum: new ideas wishlist & general chat
Topic: what should i write next?
Replies: 364
Views: 37280

Re: what should i write next?

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...
by cmorley
Fri Jan 08, 2021 4:58 pm
Forum: new ideas wishlist & general chat
Topic: what should i write next?
Replies: 364
Views: 37280

Re: what should i write next?

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.
by cmorley
Thu Jan 07, 2021 11:54 am
Forum: off-topic
Topic: LOLPRICE
Replies: 3059
Views: 379743

Re: LOLPRICE

£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
by cmorley
Sat Jan 02, 2021 7:19 am
Forum: 8-bit acorn hardware
Topic: Unknown upgrade functions, new beeb owner
Replies: 12
Views: 573

Re: Unknown upgrade functions, new beeb owner

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.
by cmorley
Fri Jan 01, 2021 3:20 pm
Forum: 8-bit acorn hardware
Topic: Unknown upgrade functions, new beeb owner
Replies: 12
Views: 573

Re: Unknown upgrade functions, new beeb owner

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...
by cmorley
Fri Jan 01, 2021 10:30 am
Forum: 8-bit acorn hardware
Topic: Unknown upgrade functions, new beeb owner
Replies: 12
Views: 573

Re: Unknown upgrade functions, new beeb owner

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....
by cmorley
Wed Dec 30, 2020 12:52 pm
Forum: off-topic
Topic: Mancave advice needed!
Replies: 10
Views: 516

Re: Mancave advice needed!

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.
by cmorley
Tue Dec 29, 2020 10:18 am
Forum: 8-bit acorn software: other
Topic: !Boot
Replies: 9
Views: 344

Re: !Boot

Would soft keys work for you? Program the soft key in the !BOOT & invoke.
by cmorley
Sat Dec 26, 2020 11:16 pm
Forum: programming
Topic: Notepad++ with BBC Basic?
Replies: 9
Views: 416

Re: Notepad++ with BBC Basic?

I use this one I found on the internet years ago. I can't remember the original credit.
by cmorley
Sat Dec 26, 2020 10:06 am
Forum: 8-bit acorn hardware
Topic: Did the Master ever get a second RISC processor?
Replies: 8
Views: 544

Re: Did the Master ever get a second RISC processor?

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 :)
by cmorley
Thu Dec 24, 2020 8:55 am
Forum: 8-bit acorn hardware
Topic: Program Corruption in memory
Replies: 16
Views: 780

Re: Program Corruption in memory

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...
by cmorley
Tue Dec 22, 2020 5:47 am
Forum: 8-bit acorn hardware
Topic: Help Please - CPLD Fitter Issues
Replies: 16
Views: 517

Re: Help Please - CPLD Fitter Issues

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.
by cmorley
Mon Dec 21, 2020 8:39 am
Forum: off-topic
Topic: Forgetful Television
Replies: 6
Views: 405

Re: Forgetful Television

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...
by cmorley
Mon Dec 21, 2020 6:47 am
Forum: 8-bit acorn hardware
Topic: BBC Model B and continuous beep unless S25 is set south..
Replies: 16
Views: 720

Re: BBC Model B and continuous beep unless S25 is set south..

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...
by cmorley
Sun Dec 20, 2020 6:36 am
Forum: new projects and releases: demoscene
Topic: b-tracker
Replies: 15
Views: 708

Re: b-tracker

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...
by cmorley
Sat Dec 19, 2020 11:58 am
Forum: 8-bit acorn hardware
Topic: BBC Model B and continuous beep unless S25 is set south..
Replies: 16
Views: 720

Re: BBC Model B and continuous beep unless S25 is set south..

Those screenshots do look weird. You might well have 2 faults, a RAM fault + a video fault :/
by cmorley
Sat Dec 19, 2020 10:36 am
Forum: programming
Topic: Reclaiming sound, serial, speech etc workspace
Replies: 14
Views: 535

Re: Reclaiming sound, serial, speech etc workspace

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. ...
by cmorley
Fri Dec 18, 2020 7:59 am
Forum: 8-bit acorn hardware
Topic: Write-up of Western Security floppy disc protection
Replies: 11
Views: 739

Re: Write-up of Western Security floppy disc protection

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...
by cmorley
Fri Dec 18, 2020 7:27 am
Forum: 8-bit acorn hardware
Topic: BBC Model B and continuous beep unless S25 is set south..
Replies: 16
Views: 720

Re: BBC Model B and continuous beep unless S25 is set south..

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...
by cmorley
Tue Dec 15, 2020 6:11 pm
Forum: off-topic
Topic: Soldering help - tip shaft sizes.
Replies: 20
Views: 737

Re: Soldering help - tip shaft sizes.

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.

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