Search found 444 matches

by crj
Thu Jan 18, 2018 11:40 pm
Forum: for sale / freebies
Topic: Rombox Plus, Pegasus 400 Disk System etc. for sale
Replies: 6
Views: 275

Re: Rombox Plus, Pegasus 400 Disk System etc. for sale

alan50 wrote:(You aren't anywhere near Birmingham airport, by chance, I suppose?)

I'm not, I'm in Cambridgeshire.

On the other hand, on Sunday I'm driving back from the ABug meeting in Manchester...
by crj
Thu Jan 18, 2018 3:57 pm
Forum: other vintage computer hardware, software and games
Topic: Reading EPROMS
Replies: 10
Views: 270

Re: Reading EPROMS

While most complex ICs have protection diodes on their inputs which might make over-voltage OK, or at least mean that a series resistor sufficed as protection, so far as I'm aware the precise details have never been published for (any of the various versions of) the Raspberry Pi. It's probably a goo...
by crj
Thu Jan 18, 2018 8:22 am
Forum: hardware
Topic: How do Beebs break in transit?
Replies: 10
Views: 360

Re: How do Beebs break in transit?

Yes, sorry. S26. (I got it right in the initial posting.) What you see is consistent with what I saw: link unset being similar to what I'd expect with it set east, so presumably that's where the line happens to float. Thanks for that data point. But the seller had photos of it working, and video was...
by crj
Thu Jan 18, 2018 5:24 am
Forum: hardware
Topic: Large project box
Replies: 5
Views: 236

Re: Large project box

Sounds like you want a Hammond 1456WL1BKBU. Or near equivalent.

FWIW, I got there by searching for "industrial console enclosure".
by crj
Thu Jan 18, 2018 2:41 am
Forum: hardware
Topic: How do Beebs break in transit?
Replies: 10
Views: 360

Re: How do Beebs break in transit?

You can eliminate the keyboard (cable) as a cause by removing the system VIA and see if it boots. Really? A beeb can boot without its System VIA? I never knew that! To recap one specific question: can someone confirm that there's no way you'll get sensible video output from a Beeb with link S28 [Ed...
by crj
Wed Jan 17, 2018 11:31 am
Forum: software: other
Topic: ASBAS Assembly Orientated BASIC
Replies: 5
Views: 204

Re: ASBAS Assembly Orientated BASIC

Kevin Edwards wrote:This new code has been located over the transdendental functions ( sin/cos etc. ).

Curious!

If it's running in the second processor, there's no real need to stay within 16Kbytes. I wonder why they didn't just lower HIMEM a little and have everything.
by crj
Wed Jan 17, 2018 11:26 am
Forum: software: other
Topic: Accessing ROMs from the 6502 second processor
Replies: 8
Views: 351

Re: Accessing ROMs from the 6502 second processor

It's a bit odd that OSRDRM wasn't implemented 'across the tube' as it was designed to be the 'clean' way to access IO processor ( and ROM ) memory in the first place. I'm sure there's a good explanation why. I get the impression it was designed for the ROM filing system, but was exported as a publi...
by crj
Wed Jan 17, 2018 9:18 am
Forum: hardware
Topic: How do Beebs break in transit?
Replies: 10
Views: 360

How do Beebs break in transit?

Having finally won an eBay auction for a BBC B, it was dead on arrival. The seller seems like a nice guy and I'm inclined to believe that it was working before it went into the cardboard box, and it was well packed albeit not in the original packaging. But now it does the dreaded long beep. Caps Loc...
by crj
Mon Jan 15, 2018 4:57 pm
Forum: hardware
Topic: BBC B Running slow
Replies: 11
Views: 465

Re: BBC B Running slow

I commented suspecting stray interrupts (of either flavour). But then I read the fault description again and deleted my comment.

I'm struggling to see any way that stray interrupts would suddenly clear up the moment you entered BASIC!
by crj
Mon Jan 15, 2018 4:25 pm
Forum: for sale / freebies
Topic: Rombox Plus, Pegasus 400 Disk System etc. for sale
Replies: 6
Views: 275

Re: Rombox Plus, Pegasus 400 Disk System etc. for sale

I'd be interested in the Electron and Rombox Plus for about forty quid. I'm not interested in the disk system.

But I'd quite understand if you were looking for more money than that, and/or wanting to sell everything together.
by crj
Mon Jan 15, 2018 4:23 pm
Forum: programming
Topic: 32k memory management for dummies
Replies: 28
Views: 762

Re: 32k memory management for dummies

Thank you! That was bugging me. I knew that I could remember an implementation of filing system 0 from somewhere, but my hazy memory was leaning towards somehow ending up with no filing systems under fileswitch on the Archimedes.
by crj
Mon Jan 15, 2018 4:17 pm
Forum: programming
Topic: Many DEFPROC, 1 ENDPROC?
Replies: 17
Views: 1046

Re: Many DEFPROC, 1 ENDPROC?

If you want the compiler to be able to work out that it's safe to lift a strlen call out of a loop, you need it to know two things: ⋅ strlen() is a pure function (it has absolutely no side effects; it's impossible to tell if you called it once or twice) ⋅ The string its argument ...
by crj
Mon Jan 15, 2018 3:46 pm
Forum: off-topic
Topic: How many people found computer self-assembly annoying?
Replies: 10
Views: 349

Re: How many people found computer self-assembly annoying?

To me, soldering is just another simple repetitive manual task. I'm fine at it, and indeed back when I was a student I assembled a bunch of podules as a summer job, but it's hardly something I'd do for fun.
by crj
Mon Jan 15, 2018 3:37 pm
Forum: general
Topic: Today I received.....
Replies: 4350
Views: 265189

Re: Today I received.....

A sample of the Samtec ZA8 : http://www.nsict.org/~clive/misc/za8-fingertip.jpg Fingertip for scale. This is an awesome little thing: 12.5mm by 9mm by 1mm thick, with 100 sprung contacts on each face, to carry fast signals between parallel boards. The interesting point from my perspective is that it...
by crj
Mon Jan 15, 2018 12:34 am
Forum: programming
Topic: 32k memory management for dummies
Replies: 28
Views: 762

Re: 32k memory management for dummies

I remain unsure what the correct behaviour is if someone attempts to select filing system 0... Filing system zero ois defined to not exoist. It means "no filing system" Yes, but I'm not aware of any null filing system, let alone any way to select it. Which, as I say, means it's not clear ...
by crj
Sun Jan 14, 2018 9:02 am
Forum: off-topic
Topic: Decoupling capacitor for ic
Replies: 11
Views: 302

Re: Decoupling capacitor for ic

daveejhitchins wrote:Pete's reckoning was: if it works without decoupling capacitors then when there're added the design should be stable for production.

That's just tempting fate into letting yours be one of those rare designs that's broken by additional caps. :-p
by crj
Sun Jan 14, 2018 3:52 am
Forum: emulators
Topic: Variations on OSGBPB
Replies: 4
Views: 164

Re: Variations on OSGBPB

The version of OSGBPB 9 that mdfs.net documents seems to be the one provided by OS_GBPB 9 under RISC OS. I wasn't aware it ever existed on 8-bit OSes, which might explain why VDFS does something different with it. While we're here: I've been thinking it would be nice to have a pair of "write ze...
by crj
Sat Jan 13, 2018 6:06 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 54
Views: 1295

Re: SpectROM - Speccy emulator for the Pi co-pro

If you're writing to the tube from emulated hardware, i.e. directly within the PiTubeDirect code, maybe you can be certain of keeping the FIFO from becoming empty? If so, you could go a little faster by not polling the status register.
by crj
Sat Jan 13, 2018 5:43 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 54
Views: 1295

Re: SpectROM - Speccy emulator for the Pi co-pro

Currently only type 0 and 1 are implemented, but the framework is there for them all to be added: https://github.com/hoglet67/PiTubeDirect/blob/master/src/tube-isr.c#L388 Gosh. I'd have expected filing systems to use the page-based reads and writes for bulk transfer. If PiTubeDirect in native mode ...
by crj
Sat Jan 13, 2018 5:35 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 54
Views: 1295

Re: SpectROM - Speccy emulator for the Pi co-pro

But in the Life example that's being discussed, what's actually being set is effectively compressed, because only changes are being send. As I said: the Beeb end can do what it wants with each byte it receives Having initiated a memory transfer from the Parasite, it needn't simply drop the bytes in...
by crj
Sat Jan 13, 2018 4:14 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 54
Views: 1295

Re: SpectROM - Speccy emulator for the Pi co-pro

Isn't the defined - and quickest - way to do this stuff for the Parasite to provoke the Host into initiating a memory transfer? 256-byte blocks can be transmitted at the rate of 100Kbytes per second, because of the reduced handshaking overheads. And the Beeb end can do what it wants with each byte i...
by crj
Sat Jan 13, 2018 2:49 pm
Forum: hardware
Topic: Recurrent corrupted discs - possible floppy drive fault?
Replies: 17
Views: 366

Re: Recurrent corrupted discs - possible floppy drive fault?

I would have expected the highest priority rom (AP6) to just accept the command and overrule the others, but it seems that the other roms are interfering with it. Be aware that there is a distinction between utility commands and filing-system commands. Filing-system commands are ones provided by th...
by crj
Fri Jan 12, 2018 4:03 pm
Forum: software: other
Topic: Adventure games: written in assembler? What compression?
Replies: 6
Views: 302

Re: Adventure games: written in assembler? What compression?

perhaps you can say something about how whatever it was they did with BCPL related to, and interacted with, whatever they did using "T/SAL"? BCPL is the language they wrote T/SAL in. I'm afraid I never really investigated the innards of T/SAL. To run on the BBC micro they were in effect c...
by crj
Fri Jan 12, 2018 3:44 pm
Forum: off-topic
Topic: Internet of Strings
Replies: 8
Views: 277

Re: Internet of Strings

Is it bad that RFC 1149 is one of the ones I recognise by number? (Pedantry: RFCs aren't standards; they're requests for comment with a view to later being put on the standards path. There are only 90 actual standards.)
by crj
Fri Jan 12, 2018 4:45 am
Forum: software: other
Topic: Adventure games: written in assembler? What compression?
Replies: 6
Views: 302

Re: Adventure games: written in assembler? What compression?

I definitely remember there being a significant BASIC component to Philosopher's Quest. I doubt there was any machine code at all, though they may well have tacked some binary data on the end of the program for the sake of compactness. The Topologika games were in general developed on Cambridge Univ...
by crj
Fri Jan 12, 2018 4:32 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 1037

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Are you playing a hacked version?

Immediately after an OSFILE, that has the whiff of a place where copy protection code has been removed.
by crj
Thu Jan 11, 2018 4:44 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 111
Views: 4006

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

I feel like I'm asking a dumb question, but...

What time do activities begin and end each day? I can't see that information anywhere!
by crj
Wed Jan 10, 2018 11:11 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 111
Views: 4006

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

Some bright spark should make conductive Blu Tack. Nod.

(I believe genuine Blu Tack is as near nonconductive as makes no odds, but several of the clones conduct enough to be scary when used to bodge mains electrics.)
by crj
Wed Jan 10, 2018 10:49 pm
Forum: hardware
Topic: Electron cassette counter revolution rate
Replies: 26
Views: 571

Re: Electron cassette counter revolution rate

Huh? Unless this conversation has gone very wrong, we're discussing two alternative implementations of compact cassette deck: ⋅ One motor, which drives the capstan directly and the take-up spool through a clutch ⋅ Two motors, one driving the capstan, one the take-up spool If the ...

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