Search found 1149 matches

by SarahWalker
Thu Apr 11, 2019 8:06 pm
Forum: emulators
Topic: Sound comparison (CTRL-G) real Elk and 4 emulators
Replies: 9
Views: 333

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: 2666

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: 174

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: 2666

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: 2666

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: 2666

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: 305

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: 815

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: 411

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: 525

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: 525

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: 525

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: 525

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: 574

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: 7
Views: 449

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: 7
Views: 449

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: 824

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: 824

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: 824

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: 824

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 ...
by SarahWalker
Mon Feb 04, 2019 9:00 pm
Forum: emulators
Topic: Arthur under emulators
Replies: 7
Views: 449

Re: Arthur under emulators

Floppies definitely work under Arthur on Arculator 0.99. Are you sure you're not trying to access ADFS E format discs? Arthur only supports D.
by SarahWalker
Sat Feb 02, 2019 12:08 pm
Forum: projects
Topic: New game - tube type thingy
Replies: 54
Views: 5043

Re: New game - tube type thingy

I've now abandoned this - it just wasn't working as a game. I've uploaded the source + a disc image to https://github.com/stardot/Toob if anyone wants to play with it.
by SarahWalker
Wed Jan 16, 2019 6:28 pm
Forum: hardware
Topic: Romcs* observations
Replies: 5
Views: 341

Re: Romcs* observations

Experimental observations -- this code: MOV R0, #&3800000 .L LDR R1, [R0] B L ... results in Romcs* looping through this pattern: 0.35us low 0.15us high (B L) 0.1us low 0.15us high 0.1us low 0.27us high Presumably that's actually something like: 0.25us (2 clocks) - Read 0x3800000 0.1us + 0.15us (2 ...
by SarahWalker
Tue Jan 08, 2019 8:32 am
Forum: emulators
Topic: Arculator & Risc OS 2.0
Replies: 3
Views: 419

Re: Arculator & Risc OS 2.0

Not in v0.99 unfortunately. The next version (which will be out this year! Honest!) will have both ST-506 and IDE podule emulation.
by SarahWalker
Sun Jan 06, 2019 8:45 pm
Forum: wanted
Topic: Acorn A3000 ARM 3
Replies: 23
Views: 838

Re: Acorn A3000 ARM 3

I suspect if you'd spent £500 on an FPA, the question wouldn't be 'what software can use the FPA' but 'what software is actually noticeably improved by having an FPA'? Which owing to the chicken and egg situation regarding floating point on the Arc would be very little!
by SarahWalker
Sun Jan 06, 2019 11:52 am
Forum: wanted
Topic: Acorn A3000 ARM 3
Replies: 23
Views: 838

Re: Acorn A3000 ARM 3

Not a lot :) There's not much point writing FPU dependent software if no one owns one. I ended up using POVray to test Arculator's FPA emulation as there's so little else that exercises it.

eBay is up to three chips now. And two of them are £500!
by SarahWalker
Thu Jan 03, 2019 6:04 pm
Forum: wanted
Topic: Acorn A3000 ARM 3
Replies: 23
Views: 838

Re: Acorn A3000 ARM 3

Cutter wrote:
Thu Jan 03, 2019 5:56 pm
2. Your chances of finding an FPA, even from CJE Micros, are basically nil
Surprisingly, they do currently claim to have one, if you have £250 burning a hole in your pocket :shock:

They also list A3000 ARM3 upgrades, at a typical CJE price.
by SarahWalker
Thu Jan 03, 2019 4:06 pm
Forum: general
Topic: Date of last (final) use of BBC Micros in classrooms?
Replies: 35
Views: 1564

Re: Date of last (final) use of BBC Micros in classrooms?

We definitely still had a BBC per classroom when I left primary school, in 1998, and they were still being actively used. There were Beebs at my secondary school, for at least the first couple of years, though I don't remember ever using them; though Arcs were still in use at that point. We did late...
by SarahWalker
Mon Dec 31, 2018 5:02 pm
Forum: other vintage computer hardware, software and games
Topic: Old School PC Hardware Clear Out.
Replies: 10
Views: 635

Re: Old School PC Hardware Clear Out.

I thought Imagination were only responsible for the Matrox M3D (PowerVR PCX2)? The Mystique and G400 were Matrox's own in-house designs.