Search found 1158 matches

by SarahWalker
Sun Jun 23, 2019 8:08 am
Forum: software
Topic: New demo - Horizon
Replies: 5
Views: 195

New demo - Horizon

Hi everyone! As keiranhj mentioned in the Nova 19 thread, I've released a new Archimedes demo - Horizon. According to pouet.net, the last Arc demo that wasn't a port was released back in 2003, so this is the first for a while! This is the 'party version' - ie it's a bit buggy. The target machine was...
by SarahWalker
Wed Jun 05, 2019 4:43 pm
Forum: emulators
Topic: Elkulator Debugger
Replies: 2
Views: 109

Re: Elkulator Debugger

The only documentation is the help text. There's not much too it; it's only basic breakpoint/watchpoint & single step functionality.
by SarahWalker
Sat May 25, 2019 9:28 pm
Forum: programming
Topic: Direct keyboard access on BBC?
Replies: 5
Views: 247

Re: Direct keyboard access on BBC?

Your &FE40 write disabled keyboard auto scan. LDA #&0b: STA &FE40 should turn it back on again. The BBC keyboard effectively operates in two modes. Rich's link describes the manual non-IRQ mode. In automatic mode CA2 will fire if a key is pressed; though at that point you have to switch back to manu...
by SarahWalker
Sat May 18, 2019 6:30 pm
Forum: emulators
Topic: Revs on B-Em
Replies: 9
Views: 411

Re: Revs on B-Em

and, not spotting that the variable names were subtly different I need to go back in time 10 years and give myself a smack for that. Now I just need to work out where the accelerator is. I have found the steering controls and then up/down gear but nothing seem to make the car move from the spot. T ...
by SarahWalker
Sat May 18, 2019 5:59 pm
Forum: emulators
Topic: Revs on B-Em
Replies: 9
Views: 411

Re: Revs on B-Em

Technically an interlaced screen is 312.5 lines per field, or 40,000 CPU cycles. However, this strictly depends on when you measure a 'field' as having completed. With B-em, measuring between video_doblit() calls will show field length alternating between 312 and 313 lines, or 39,936 and 40,064 cycl...
by SarahWalker
Sat May 18, 2019 11:55 am
Forum: emulators
Topic: Revs on B-Em
Replies: 9
Views: 411

Re: Revs on B-Em

Revs does reprogram the palette several times during the frame. It's unusual in that it doesn't base the timing of vsync every frame, as most other split palette games do, but instead just chains back-to-back VIA timer interrupts and relies on the total period adding to exactly the length of a frame...
by SarahWalker
Tue May 14, 2019 5:13 pm
Forum: emulators
Topic: 50 fps on b-em?
Replies: 18
Views: 543

Re: 50 fps on b-em?

I'm a bit surprised it's using that much CPU. When I was finishing White Light a couple of years ago, for obscure reasons I did much of the final tweaking & bug fixing on B-em v2.2 running on an Athlon 750, a CPU from 1999 (hence the 21st century comment!). It ran at (just about) full speed on that,...
by SarahWalker
Sat May 11, 2019 7:58 pm
Forum: emulators
Topic: 50 fps on b-em?
Replies: 18
Views: 543

Re: 50 fps on b-em?

No. It's assumed that if you're running on a machine made in the 21st century then it will run at 50 fps.
by SarahWalker
Sat May 11, 2019 6:52 pm
Forum: emulators
Topic: 50 fps on b-em?
Replies: 18
Views: 543

Re: 50 fps on b-em?

Running at 50 fps here on both B-em v2.2 and Beebem v4.14. B-em's frame pacing isn't great, but it's still putting out 50 fps.
by SarahWalker
Thu Apr 11, 2019 8:06 pm
Forum: emulators
Topic: Sound comparison (CTRL-G) real Elk and 4 emulators
Replies: 9
Views: 477

Re: Sound comparison (CTRL-G) real Elk and 4 emulators

The non-squarewaveness of the real machine should be a combination of filtering, noise/interference and poor frequency response of the cheap speaker.
by SarahWalker
Thu Apr 04, 2019 5:05 pm
Forum: hardware
Topic: Phoebe PCB
Replies: 34
Views: 2811

Re: Phoebe PCB

FWIW, I did do some reverse engineering of Phoebe and the IOMD20 chip based on the RISC OS 3.8 ROM from CCH's machine a few years ago, which made its way into RPCemu. So at least _some_ of it got preserved.
by SarahWalker
Tue Apr 02, 2019 9:10 pm
Forum: software: classic games
Topic: Beeb bomerman style game?
Replies: 5
Views: 252

Re: Beeb bomerman style game?

danielj wrote:
Tue Apr 02, 2019 6:58 pm
I think it needed someone to do new graphics?
Yep - it's used ripped Bomberman graphics so far.
by SarahWalker
Tue Apr 02, 2019 4:55 pm
Forum: hardware
Topic: Phoebe PCB
Replies: 34
Views: 2811

Re: Phoebe PCB

It's much too late for that - it killed the TNMOC Phoebe a few years ago. And those were the only two Phoebes in existence.
by SarahWalker
Mon Apr 01, 2019 8:03 pm
Forum: hardware
Topic: Phoebe PCB
Replies: 34
Views: 2811

Re: Phoebe PCB

The CCH Phoebe is now dead unfortunately.
by SarahWalker
Mon Apr 01, 2019 4:28 pm
Forum: hardware
Topic: Phoebe PCB
Replies: 34
Views: 2811

Re: Phoebe PCB

If by 'last version' you mean the original RiscPC, then yes - faster RAM, more video memory, PCI slots, faster IDE interface, improved audio hardware. Though not all of these supported in RISC OS at the time the machine was canned. And it wasn't enough to catch up with 1998/1999 PC hardware in any c...
by SarahWalker
Thu Mar 28, 2019 8:37 pm
Forum: general
Topic: Can the BBC's tape out be used as a second sound channel?
Replies: 6
Views: 369

Re: Can the BBC's tape out be used as a second sound channel?

No, the BBC (and Electron) sound hardware can only output 1200 and 2400 Hz tones, so pretty useless for sound output.
by SarahWalker
Mon Mar 18, 2019 5:49 pm
Forum: software
Topic: Help with a forlorn A3010 please
Replies: 42
Views: 949

Re: Help with a forlorn A3010 please

For the hard drive, try '*configure idefsdiscs 1'. You might also need '*configure idefsdrives 1'; this depends on the version of IDEFS on the podule. Have a look at what *status gives, the IDEFS options should be near the bottom of the list. IDEDiscs and HardDiscs should both be 0 as neither are re...
by SarahWalker
Mon Mar 11, 2019 8:56 pm
Forum: programming
Topic: 6502, 65SC12, 65C102, huh?
Replies: 8
Views: 502

Re: 6502, 65SC12, 65C102, huh?

tricky wrote:
Mon Mar 11, 2019 8:03 am
Did all of the B+ have Rockwell R6512AP and which BASIC?
IIRC the B+'s 6512 is just an NMOS 6502 with different clock inputs and not a 65c12 with new instructions. As a result it runs BASIC II.
by SarahWalker
Fri Mar 08, 2019 9:42 pm
Forum: software
Topic: Detecting Risc PC vs earlier machines in assembly code
Replies: 12
Views: 611

Re: Detecting Risc PC vs earlier machines in assembly code

That would require RISC OS to be present and running. myelin is coding bare metal.
by SarahWalker
Fri Mar 08, 2019 6:38 pm
Forum: software
Topic: Detecting Risc PC vs earlier machines in assembly code
Replies: 12
Views: 611

Re: Detecting Risc PC vs earlier machines in assembly code

ROM is always mapped at 0 in the RiscPC's physical address space. RISC OS maps it to 0x3800000 in the virtual address space using the MMU.

On MEMC systems, 0x2000000-0x3ffffff are never subject to translation and hence 0x3800000 is the physical location of ROM.
by SarahWalker
Wed Mar 06, 2019 10:20 pm
Forum: software
Topic: Detecting Risc PC vs earlier machines in assembly code
Replies: 12
Views: 611

Re: Detecting Risc PC vs earlier machines in assembly code

Another possibility might be to try reading from 0x1000000 - on IOMD this is explicitly 'extension ROM', which at the very least would differ from normal ROM, whereas on MEMC this might mirror? It's not clear from the MEMC datasheet which ROM is continually enabled, if it's always high ROM (0x380000...
by SarahWalker
Wed Mar 06, 2019 10:14 pm
Forum: software
Topic: Detecting Risc PC vs earlier machines in assembly code
Replies: 12
Views: 611

Re: Detecting Risc PC vs earlier machines in assembly code

You could use the CP15 ID register (assuming you can handle an illegal instruction exception on ARM2/250 machines); if it returns ARM6 or later then that's a dead giveaway that you aren't on MEMC-based hardware. I don't think MEMC will allow you to access IO controllers without shutting the low ROM ...
by SarahWalker
Wed Mar 06, 2019 9:07 pm
Forum: software: other
Topic: When (and why) did PLOT 8-15 change?
Replies: 13
Views: 644

Re: When (and why) did PLOT 8-15 change?

It seems far less likely that this was a deliberate behaviour change, and that whoever reimplemented PLOT in MOS 3.x and Arthur/RISC OS (Richard Manby?) implemented based on the (inaccurate) written documentation and no-one noticed that it didn't match the behaviour in OS 1.20. Simple human error.
by SarahWalker
Wed Feb 20, 2019 6:02 pm
Forum: emulators
Topic: Arthur under emulators
Replies: 13
Views: 781

Re: Arthur under emulators

Yes. But 'closer' does not imply 'close'.
by SarahWalker
Sat Feb 16, 2019 6:08 pm
Forum: emulators
Topic: Arthur under emulators
Replies: 13
Views: 781

Re: Arthur under emulators

sirbod wrote:
Sat Feb 16, 2019 4:30 pm
I'm using the binary you sent me many moons ago (to test JFD support), so it's possible you've since fixed it since. I've no idea what build it is, but the EXE is dated 15-03-16.
I wouldn't use that binary as evidence of anything. 0.99 is the most recent stable version.
by SarahWalker
Wed Feb 13, 2019 8:45 pm
Forum: general
Topic: Bit of fun Part Two - CPU Swap
Replies: 28
Views: 917

Re: Bit of fun Part Two - CPU Swap

I wonder what effect it would have had on game availability. Did the writers of games BITD typically keep the code that tracked the interaction of the characters separate from that which manipulated the hardware, such that having the same processor as another popular machine would mean only half th...
by SarahWalker
Wed Feb 13, 2019 7:33 pm
Forum: general
Topic: Bit of fun Part Two - CPU Swap
Replies: 28
Views: 917

Re: Bit of fun Part Two - CPU Swap

Another though - having a Z80 and CP/M capability as standard might also have put pressure on Acorn to have a 64kb option rather sooner than they did in our 6502 universe? CP/M applications do like to have all the RAM, and a 32kb-only CP/M box would have quickly become quite limited I think. 6809 wo...
by SarahWalker
Tue Feb 12, 2019 10:09 pm
Forum: general
Topic: Bit of fun Part Two - CPU Swap
Replies: 28
Views: 917

Re: Bit of fun Part Two - CPU Swap

I can't recall if the Acorn Z80 Co-Pro actually came with a Z80 version of B Basic or not. It did, implemented as a CP/M application from memory. Regarding purpose, well I guess the other co-pro's were not heavily used either such as the '86 based ones ? They weren't heavily used, but they did for ...
by SarahWalker
Tue Feb 12, 2019 8:15 pm
Forum: general
Topic: Bit of fun Part Two - CPU Swap
Replies: 28
Views: 917

Re: Bit of fun Part Two - CPU Swap

obviously there would be a 6502 co-pro to add on the same as there's a Z80 one now Why? The whole point of the Z80 copro is there was another OS to run, CP/M. There's no equivalent OS for the 6502, so what would be the purpose of a 6502 copro in this scenario? For the uniprocessor machine, I don't ...