Search found 821 matches

by Coeus
Sun Jul 15, 2018 7:33 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 303

Re: Datel Modem 1979 to 1982, anyone used it?

I think I have just spotted one of these in use in Episode 10 "At The End of the Line" of "Making the Most of the Micro" at about 11:45. See this still:
Screenshot from 2018-07-15 20-14-36.png
by Coeus
Sun Jul 15, 2018 2:03 pm
Forum: software: other
Topic: Today I hacked ...
Replies: 86
Views: 9183

Re: Today I hacked ...

by 8271 you don't need track 0 , sec 0 sec1 and sec2. look at my disc protect systeem :). if the 8271 do not find after index hole track 0,sec0,1 it steps 255 times all over de disc to find it :) so track 0 sec1,sec2 can be at track 9 the only thing you have to do is make track 9 the ids for track ...
by Coeus
Sun Jul 15, 2018 8:36 am
Forum: software: other
Topic: Today I hacked ...
Replies: 86
Views: 9183

Re: Today I hacked ...

yeah, but how ? When reading, I would not expect the disc controller to use the index hole at all. It will simply start reading data until it finds the ID for the specified sector and will then generate the interrupt to start transferring that sector. So, with all the sectors having the same ID whi...
by Coeus
Sat Jul 14, 2018 8:13 pm
Forum: programming
Topic: Files created by OPENOUT
Replies: 4
Views: 191

Re: Files created by OPENOUT

Are there any technical details of the file format used by files created using the OPENOUT command function? Any files created by any method have no format, they are pure binary. Any internal format of the binary data is entirely and completely down to the programmer chosing what to so with it. It ...
by Coeus
Wed Jul 11, 2018 4:36 pm
Forum: off-topic
Topic: Football
Replies: 8
Views: 189

Re: Football

I probably will be watching the match but I am not proposing to watch the hype before hand or the endless analysis afterwards. The pundits have quite enough time in between the two halves to chinwag. Until kickoff I am listening to music and staying away from media that may choose to speculate about...
by Coeus
Tue Jul 10, 2018 6:31 pm
Forum: software: other
Topic: CP/M Hard Disc BIOS
Replies: 1
Views: 82

CP/M Hard Disc BIOS

Questions, probably for JGH: Disc http://mdfs.net/Mirror/Image/AcornCPM/JGHCPM1.zip is a CP/M bootable disc with a hard disc BIOS. 1. Does this make any assumptions about the disc interface, i.e. SCSI or IDE. 2. Does it need reserved tracks on the disc or does it turn an ADFS file into a virtual har...
by Coeus
Tue Jul 10, 2018 6:26 pm
Forum: software: other
Topic: Acorn CP/M disc format
Replies: 1
Views: 92

Acorn CP/M disc format

I notice Acorn CP/M format discs have a fake DFS catalogue at the start on side 0. As far as I can work out this contains a single file that occupies the whole disk (side) and thus ensures the user cannot save files to the disc from DFS and overwrite CP/M files. Shouldn't there be a similar fake cat...
by Coeus
Tue Jul 10, 2018 6:20 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 227

Re: CP/M text Editor Required

The other thing I forgot to suggest is that all the other obscure commands can be programmed into function keys with *KEY and you could make a keystrip with a suitable legend. To set up some things ready for running VDE for the first time in any one session you can always place the commands in a SUB...
by Coeus
Tue Jul 10, 2018 4:16 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 227

Re: CP/M text Editor Required

Further to my last post, here is a disc (in Acorn CP/M format, so ready to go on Z80 2nd proc) with VDE configured for the BBC micro, i.e. I have been through the installation program and set up the terminal control sequences to be the BBC VDU sequences. The other half of the picture, i.e. making th...
by Coeus
Tue Jul 10, 2018 3:42 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 303

Re: Datel Modem 1979 to 1982, anyone used it?

1024MAK wrote:
Tue Jul 10, 2018 12:24 pm
MODEMs designed only for exchange line use normally need something to simulate the exchange...
For an auto dialing modem this simulation would need to be more complete but without autodial I wonder if you could get away with connecting a pair of these back to back and just provide the DC 50V.
by Coeus
Tue Jul 10, 2018 12:45 pm
Forum: software: other
Topic: CP/M text Editor Required
Replies: 9
Views: 227

Re: CP/M text Editor Required

...ED for me is completely unusable... I remember thinking that, back in the day. Then, I didn't understand why "they" (Digital Research) thought a line editor was a good idea but at that age I didn't have a sense of how fast progress in computing had been and that when CP/M was designed having a V...
by Coeus
Tue Jul 10, 2018 9:51 am
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

Re: BASIC FOR loops

I disagree. Perhaps it is a little confusing for the beginner but it is the equivalent to "break [n];" in C. A very useful feature for more advanced program flow control. In the the case of the Mandelbrot program that started this, it is only a single level of break in equivalent C. Here's the part...
by Coeus
Tue Jul 10, 2018 9:06 am
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

Re: BASIC FOR loops

Soruk wrote:
Mon Jul 09, 2018 10:18 pm
Hi,

Your patch works a treat for that Mandelbrot thing over in the other thread.

May I include it in my fork of Brandy?
Yes, that's fine.
by Coeus
Mon Jul 09, 2018 9:24 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

Re: BASIC FOR loops

Ok, so to follow up my post it seems there is an ANSI standard for BASIC, I just wasn't aware of it. That doesn't make any material difference, though, as I was specifically asking about Acorn BASICs.
by Coeus
Mon Jul 09, 2018 9:11 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

Re: BASIC FOR loops

The phrase "Implementation defined behaviour" sounds like what you'd expect to in a language standard but I was not aware of any effort to produce a proper language standard for BASIC. As a practical matter, across BASIC implementations in general this does seem to vary. For example on CP/M Microsof...
by Coeus
Mon Jul 09, 2018 7:54 pm
Forum: emulators
Topic: emulator cycle vs walclock vs TIME accuracy
Replies: 8
Views: 467

Re: emulator cycle vs walclock vs TIME accuracy

I was trying to make sense of these figures from Brandy BASIC: Screenshot from 2018-07-09 19-33-46.png The overall theme seems to be that Brandy on my PC is a bit over 36,000 X as fast as a BBC unless floating point is involved in which case having hardware floating point is making an even bigger di...
by Coeus
Mon Jul 09, 2018 7:31 pm
Forum: software: other
Topic: Border tracing Mandelbrot generator for the Beeb
Replies: 83
Views: 6268

Re: Border tracing Mandelbrot generator for the Beeb

I've got a different mandelbrot that is using nested FOR loops working fine in Brandy. It would be interesting to see that to compare. Brandy can obviously do nested for loops but its setting an extra constraint compared to Acorn BASICs that the next needs to match the most recent FOR. I think the ...
by Coeus
Mon Jul 09, 2018 6:34 pm
Forum: emulators
Topic: Ceefax Engineering Test Page - BeebEm 4.13 & B-em
Replies: 67
Views: 10750

Re: Ceefax Engineering Test Page - BeebEm 4.13 & B-em

Just popping my head above the parapet here to say this thread has been a very useful resource in my attempt to make a reasonable emulation of Teletext work in Brandy BASIC V, along with a few Risc OS 5 extensions controlled via VDU23,18 as documented by BeebWiki. If anyone is interested I've put i...
by Coeus
Mon Jul 09, 2018 6:11 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

Re: BASIC FOR loops

Ok, then in that case here is a patch to brandy basic that makes it behave like Acorn BASIC with these loops: --- brandy-1.21.2-orig/src/mainstate.c 2013-06-28 15:23:16.000000000 +0100 +++ brandy-1.21.2-patched/src/mainstate.c 2018-07-09 18:49:29.975604126 +0100 @@ -1301,6 +1301,20 @@ /* ** 'exec_ne...
by Coeus
Mon Jul 09, 2018 4:27 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 271

BASIC FOR loops

I mentioned in another thread in which a Mandelbrot program in BASIC was included that brandy basic does not handle FOR loops where a NEXT statement occurs for anything other than the innermost FOR loop. I had a look in original BBC Micro User guide and it advises against "bady nested" FOR loops but...
by Coeus
Sun Jul 08, 2018 4:50 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 303

Re: Datel Modem 1979 to 1982, anyone used it?

I think I have seen one of those but never used one in person, though I do remember the days of 300, then 1200, then 2400 bps. There may be two reason why it was integrated into a phone: 1. It probably wasn't auto dialing so the phone would be needed to dial the connection. 2. The post office was st...
by Coeus
Sat Jul 07, 2018 8:58 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1827

Re: BBC releases computer history archive

First programme in the series "Making the Most of the Micro" has a very cool bit with Ian McNaught-Davies appearing to walk over a macro image of what looks like it may be a BBC micro, but not an issue 7 as far as I can see. I assume the effect is a colour separation overlay? Anyway, the featured ci...
by Coeus
Sat Jul 07, 2018 6:35 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1827

Re: BBC releases computer history archive

Does anyone recognise the chip shown in episode 9 of "The Computer Programme", "In Control" at around 18 minutes. The chip being held has Ferranti on it so a ULA, possibly? That would be consistent with Ian McNaught-Davis taking about customising the chip to a particular purpose as the last step in ...
by Coeus
Tue Jul 03, 2018 9:34 pm
Forum: general
Topic: "Outline specification for the BBC MICROCOMPUTER system"
Replies: 199
Views: 16013

Re: "Outline specification for the BBC MICROCOMPUTER system"

Edit: also it took about 5 years to really take off in the home market. In that time loads of other machine had been and gone. And the home market penetration was presumably because, once there were a number of clones, at least some of the clone manufacturers were then competing to see who could pr...
by Coeus
Tue Jul 03, 2018 9:07 pm
Forum: general
Topic: "Outline specification for the BBC MICROCOMPUTER system"
Replies: 199
Views: 16013

Re: "Outline specification for the BBC MICROCOMPUTER system"

Was cloned because they could without being sued or paying huge licenses. If you think of the other systems at the time if you wanted to join the band wagon of making and selling computer it was a big investment/risk look at all the other systems on the retro channels you never heard of because abo...
by Coeus
Tue Jul 03, 2018 8:36 pm
Forum: general
Topic: "Outline specification for the BBC MICROCOMPUTER system"
Replies: 199
Views: 16013

Re: "Outline specification for the BBC MICROCOMPUTER system"

And we can only speculate how IBM would have responded to a counterfactual request for proposal, given their reputation for being non-agile and paternalistic. But, unlike typical home computers, the IBM PC was modular. It had a motherboard, a bus, and a series of cards that plugged into it. Therefo...
by Coeus
Tue Jul 03, 2018 11:33 am
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1827

Re: BBC releases computer history archive

Back to the content of these programs, I am now working my way through "The Computer Programme" and I think these are a fascinating piece of history not just for technology but the social attitudes and concerns and also lots of filming inside places I have never been. There are also old cars, old te...
by Coeus
Mon Jul 02, 2018 5:49 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1827

Re: BBC releases computer history archive

Ahh, but most computers in the 1970s, 1980s and 1990s don't actually produce a proper interlaced output. Instead they just produce a single field, then repeat the same field (and if doing animation, with different picture information). So on a large-ish screen CRT, you can see faint horizontal line...
by Coeus
Mon Jul 02, 2018 4:53 pm
Forum: general
Topic: "Outline specification for the BBC MICROCOMPUTER system"
Replies: 199
Views: 16013

Re: "Outline specification for the BBC MICROCOMPUTER system"

There is also a timeline on the CLPA site which shows the IBM PC being available in the same year the spec was distributed to manufacturers so if, as John Radcliffe implied in his interview, it was not crucial that ordinary viewers be able to afford the machine the BBC were using to demonstrate with...
by Coeus
Mon Jul 02, 2018 2:09 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1827

Re: BBC releases computer history archive

That explains why the movement looks so weird, but surely it takes more than inexperience to convert to the wrong frame rate (one not related to the original). Shame really as it is detracting from the experience of watching the ones I missed. But isn't 15fps an odd frame rate for UK TV also? If it...