Search found 2845 matches

by jgharston
Tue Jan 23, 2018 1:48 pm
Forum: hardware
Topic: Connecting SEGA Mega Drive controllers to the beeb
Replies: 23
Views: 375

Re: Connecting SEGA Mega Drive controllers to the beeb

Lardo Boffin wrote:How on earth can they make these for that price?!!!!! :shock:
Have you seen the cost of living in rural China? £5 can keep a peasant employed in an electronics factory in food and accommodation for more than a week. It's the equivalent purchasing value of about £150 in the UK.
by jgharston
Tue Jan 23, 2018 1:40 pm
Forum: hardware
Topic: Acorn's Second Processors and the Tube - what, and why
Replies: 18
Views: 945

Re: Acorn's Second Processors and the Tube - what, and why

There is an issue, though, if you are writing in assembler and expect your code to be loaded from disc into RAM rather than running from ROM because, without external tools, all but the simplest 6502 assembler is not relocatable. This is one area in which CP/M scores over the Acorn MOS because ther...
by jgharston
Tue Jan 23, 2018 1:32 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

Also, I've lost track, what's the byte arrangement in screen memory when set up for Spectrum-style display? Using MODE 0 as the base suggests the Spectrum 1bpp display bitmap is mapped directly onto some of the BBC 1bpp display bitmap, but how are the attribute bytes mapped?
by jgharston
Tue Jan 23, 2018 1:28 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

hoglet wrote:Or have I got completely the wrong end of this stick with the need for additional display memory?

Looks right. Essentially doing something similar to what ZXDisp does, which does:
MODE 9
COLOUR 128+border
CLS
VDU 28,4,27,35,4
COLOUR 128+paper
CLS
by jgharston
Tue Jan 23, 2018 3:13 am
Forum: software: other
Topic: Accessing ROMs from the 6502 second processor
Replies: 14
Views: 506

Re: Accessing ROMs from the 6502 second processor

You could run the version 1.02 OSWORD &FF driver, which lets you transfer arbitary memory between the host and any CoPro, and accesses any paged/banked memory, on the Tube Utilities disk and source at: http://mdfs.net/Software/Tube/ Accesses sideways ROMs and shadow screen memory OSWORD &FF ...
by jgharston
Tue Jan 23, 2018 2:58 am
Forum: hardware
Topic: Connecting SEGA Mega Drive controllers to the beeb
Replies: 23
Views: 375

Re: Connecting SEGA Mega Drive controllers to the beeb

It actually connects to CB2 on the system via, driving it doesn't seem to upset the 6845, but that is when I have full control. Ah, that rings a bell. So the LPSTB can generate an interupt so code can then go and read the CRTC registers. It was there in the back of my mind, but searching through th...
by jgharston
Tue Jan 23, 2018 2:39 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

I assumed the numbering of the logical colours follows the spectrum order, so that the emulator doesn't need to do any conversion. So normal blue would be colour 1 and normal red would be colour 2. Is that convention correct? BBC hardware colours and API colour numbers are %BGR (ie red, green, yell...
by jgharston
Tue Jan 23, 2018 2:21 am
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 132
Views: 4773

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

On a practical note, I get the impression the majority of people arrived by car. If so, wouldn't it make sense to pick a more rural location? That would be easier to get to by car, probably have more car parking, and likely be cheaper to hire. If we had everybody's home postcode we could write a tr...
by jgharston
Tue Jan 23, 2018 2:18 am
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 132
Views: 4773

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

I've been going through updates from ABUG Manchester. ⋅  FServers - Y2K fix for Level 3 File Server v1.24 to create v1.25 ⋅  Level2SYS - 35FD and CACD renamed as Atom and System Econet ROM images ⋅  DiskTools - Tweek to DiskToFile to give a neater display ⋅  U...
by jgharston
Tue Jan 23, 2018 2:03 am
Forum: hardware
Topic: Acorn's Second Processors and the Tube - what, and why
Replies: 18
Views: 945

Re: Acorn's Second Processors and the Tube - what, and why

My final slightly tongue-in-cheek point is that since joining Stardot I've seen at least three new threads of "where is all the 2nd processor software?" So my conclusion is perhaps "it's harder than it looks". Where are all the 2nd-processor games , perhaps. I've used tons of so...
by jgharston
Sun Jan 21, 2018 12:52 pm
Forum: hardware
Topic: Connecting SEGA Mega Drive controllers to the beeb
Replies: 23
Views: 375

Re: Connecting SEGA Mega Drive controllers to the beeb

"shouldn't work" #-o ...What's the LPSTB hack?... Firstly, sorry for the use of the word "hack", I must be getting down with the kids!" Instead of using the LPSTB input to trigger capturing the CRTC beam position for a light pen, you set it as output and use it to swap betw...
by jgharston
Sat Jan 20, 2018 5:05 pm
Forum: hardware
Topic: Connecting SEGA Mega Drive controllers to the beeb
Replies: 23
Views: 375

Re: Connecting SEGA Mega Drive controllers to the beeb

tricky wrote:Unfortunately, when I finished wiring the prototype, it was wrong!
Well, you were calling Fate on your head when you posted I am still in the process of building a proper prototype, but it shouldn't work! :)

What's the LPSTB hack? I've heard of it, but never encountered any information.
by jgharston
Sat Jan 20, 2018 1:53 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

Edit to add: A nice little trick which comes for free though, is only output a packet at all if the byte being stored is different from the byte that's already there. That could even help a routine like this enormously. I believe (without going back to Sheffield to check) that's what Speculator on ...
by jgharston
Sat Jan 20, 2018 1:47 am
Forum: programming
Topic: JGH's Docs.Comp.BBC.MemAddrs
Replies: 2
Views: 125

Re: JGH's Docs.Comp.BBC.MemAddrs

I was going to post: is the Wiki article clearer, but there's actually nothing much there! It's regarding http://mdfs.net/Docs/Comp/BBC/MemAddrs. What's bit 20 of the address for in this scheme? Nothing, just like "what's bit 4 in SHELA I/O addresses?". In the summary table towards the end...
by jgharston
Fri Jan 19, 2018 9:30 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 132
Views: 4773

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

Recently, I've had access to an EMR midi adaptor. I've tried to get that working along with a midi keyboard and a sound module but I haven't managed to figure it out as yet - maybe someone who knows what they're doing can have a play and get things going. I did an updated backup to my Compact, and ...
by jgharston
Thu Jan 18, 2018 11:38 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 132
Views: 4773

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

1024MAK wrote:Why can you never find what you want when your time is limited... :shock: :(

Do I pack everything up now, or do I plan on waking up early enough tomorrow to do it plus everything else I need to do...? :)
by jgharston
Thu Jan 18, 2018 11:36 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

[*] LDIR can do a block copy in 21 T-states per byte. Seems a bit slow, and I'm not really sure if it was used much (I think they tended to prefer an unrolled bunch of LDIs, 16 T-states each - still a bit slow). You could still optimise this on the host by outputting packets where the Beeb screen m...
by jgharston
Thu Jan 18, 2018 8:10 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

(Annoyingly, OSBYTE &79 works differently on a B/B+ than it does on the Master I've been using for testing...) Which issue is that? The only difference is that the Master keyboard has 16* columns to the Beeb's 10 columns. (*ok, technically 13 columns) RISC OS (and I think the Elk) don't impleme...
by jgharston
Thu Jan 18, 2018 8:00 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 70
Views: 1579

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

There's a handful of screen dumps here as within Spectrum SNA snapshots. The screen data starts at byte 27 and continues for &1B00 bytes. GrabScrn will extract the screen data from a SNA or SNP shapshot, and ZXDisp will display the screen memory from within a SNA or SNP snapshot.
by jgharston
Wed Jan 17, 2018 2:03 am
Forum: hardware
Topic: Plus1 Slogger ROM without cart joy interface?
Replies: 6
Views: 191

Re: Plus1 Slogger ROM without cart joy interface?

Is it possible to use the Slogger Expansion ROM in the Electron's Plus1 without also using the joystick interface that plugs into the cart socket? Specifically, can the *JOYSTICK command be used with the regular plus1 joystick ports to remap to keys? The Plus 1 *don't* have any joystick ports, regu...
by jgharston
Wed Jan 17, 2018 1:43 am
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 6
Views: 237

Re: MAME: Click (and other large ROMs)

Link? http://stardot.org.uk/forums/viewtopic.php?f=32&t=11795&p=148353#p148353 It has common code at &1f80, &3f80, &5f80, &7f80. Ta. Yes, it looks like it uses &A000 as a RAM copy of the bank paging register (the equivalent of &F4), and uses &FCFC as the paging r...
by jgharston
Wed Jan 17, 2018 1:30 am
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 132
Views: 4773

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

At the moment I don't know if I'll be arriving Friday evening or Saturday morning, as I'm supposed to be in both Sheffield and Scarborough on Friday, and still haven't had it confirmed if the Scarborough is actually happening or not.

It probably means that all I'll be bringing will be my Compact.
by jgharston
Wed Jan 17, 2018 1:26 am
Forum: emulators
Topic: BeebEm ADFS disc access bug?
Replies: 14
Views: 383

Re: BeebEm ADFS disc access bug?

It's reassuring to hear it isn't just me! Just to be clear though, - this bug appears to be totally repeatable (if using this specific floppy image) Wait a bit, you said "accessing hard disk images". - and it doesn't actually relate to the hard disc at all. You don't need to switch hd sup...
by jgharston
Wed Jan 17, 2018 1:24 am
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 6
Views: 237

Re: MAME: Click (and other large ROMs)

Pernod wrote:Does anyone have any technical details on how Click paged it's 32K ROM and 32K RAM? From a quick look at the ROM it looks like it's in 8K chunks and maybe paged with writes to &FCFC.


Link?
by jgharston
Wed Jan 17, 2018 1:23 am
Forum: software: other
Topic: Accessing ROMs from the 6502 second processor
Replies: 14
Views: 506

Re: Accessing ROMs from the 6502 second processor

"I would like to make 2nd processor compatible" 2nd processor compatible, or 6502 second processor compatible? If 2nd processor compatible, that means you're working from BASIC. If 6502 second processor compatible, that means you're restricting yourself to just the 6502 second processor. (...
by jgharston
Tue Jan 16, 2018 2:18 am
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3909

Re: VideoNuLA boards

Has anybody used the nULA board in a Master Compact? I have a floppy drive mounted internally in my Compact, before I look for my soldering iron, is the board likely to fit?
Image
by jgharston
Tue Jan 16, 2018 2:14 am
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3909

Re: VideoNuLA boards

The post on Spectrum attirbute mode reminds me of a discussion I was having with RobC earlier. The VideoNuLA support ROM allows to select the extended display features with MODE/VDU 22. It currently uses MODEs &60-&68 as a straight sequence of numbers. I mentioned that it would match the nat...
by jgharston
Tue Jan 16, 2018 1:47 am
Forum: emulators
Topic: BeebEm ADFS disc access bug?
Replies: 14
Views: 383

Re: BeebEm ADFS disc access bug?

You're not alone. Every now and then when I use ADFS to access a hard drive image and get Bad directory when mounting. I can't rememebr the exact circumstances when it happens, and I can't remember what I did to fix it. I wonder if it might be when I copy the image to another machine, update it, the...
by jgharston
Sun Jan 14, 2018 6:47 pm
Forum: programming
Topic: 32k memory management for dummies
Replies: 28
Views: 783

Re: 32k memory management for dummies

crj wrote: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"
by jgharston
Sun Jan 14, 2018 6:37 pm
Forum: software: other
Topic: BBC Basic for Z80
Replies: 26
Views: 1167

Re: BBC Basic for Z80

How do you normally gry stuff from the internet into your beeb? Do that.

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