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by SarahWalker
Wed Nov 25, 2020 4:33 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Added numbers for RiscPC w/ARM700 at 33 MHz. Unsurprisingly it's roughly between ARM610 at 30 and ARM710 at 40. ARM610 at 33 would be an interesting comparison. Sadly my board doesn't have the FPA11 installed :(
by SarahWalker
Tue Nov 17, 2020 8:15 pm
Forum: 32-bit acorn hardware
Topic: PC Card - ‘letterboxing’ DOS games
Replies: 5
Views: 178

Re: PC Card - ‘letterboxing’ DOS games

VGA on the PC displays 200 lines in a 400 line mode with line doubling (as VGA monitors don't support 15 kHz line frequencies). RiscPC doesn't support hardware line doubling, hence you get letterboxing of low res modes. The workaround for this in CRT days was to define low-res 100Hz modes, but that'...
by SarahWalker
Mon Nov 16, 2020 2:40 pm
Forum: 32-bit acorn hardware
Topic: ST506 HDD woes
Replies: 47
Views: 5327

Re: ST506 HDD woes

BeebMaster wrote:
Sun Nov 15, 2020 8:12 pm
It should be 872 cylinders, 7 heads, 17 sectors per track (for 512 bytes per sector, which I imagine the Arc ST506 interface uses):
FYI, the Arc ST-506 interface uses 32 sectors per track, 256 bytes per sector.
by SarahWalker
Wed Nov 11, 2020 7:32 pm
Forum: archive submissions
Topic: Teenage Mutant Hero Turtles World Tour
Replies: 10
Views: 373

Re: Teenage Mutant Hero Turtles World Tour

FWIW here's what I have of the Arc version. I think it needs cracking, but I'm kind of lazy.
by SarahWalker
Wed Nov 11, 2020 7:21 pm
Forum: archive submissions
Topic: Teenage Mutant Hero Turtles World Tour
Replies: 10
Views: 373

Re: Teenage Mutant Hero Turtles World Tour

Arc version is definitely written using ABC.
by SarahWalker
Wed Nov 11, 2020 4:40 pm
Forum: archive submissions
Topic: Teenage Mutant Hero Turtles World Tour
Replies: 10
Views: 373

Re: Teenage Mutant Hero Turtles World Tour

There's an Arc version in existence as well, though I'm guessing it's almost as rare as the Beeb version.
by SarahWalker
Mon Oct 19, 2020 7:01 pm
Forum: for sale / freebies
Topic: A540 RAM cards on eBay
Replies: 14
Views: 558

Re: A540 RAM cards on eBay

Fair enough...
by SarahWalker
Mon Oct 19, 2020 5:59 pm
Forum: for sale / freebies
Topic: A540 RAM cards on eBay
Replies: 14
Views: 558

Re: A540 RAM cards on eBay

I was too fast! Ended up paying 2x£55 for two cards, instead of £69 for a pair :(
by SarahWalker
Mon Oct 19, 2020 5:47 pm
Forum: for sale / freebies
Topic: A540 RAM cards on eBay
Replies: 14
Views: 558

Re: A540 RAM cards on eBay

Yoink!

(this is proving to be an expensive month)
by SarahWalker
Thu Oct 15, 2020 5:02 pm
Forum: 8-bit acorn emulators
Topic: 6502 cycle-level instruction detail
Replies: 19
Views: 880

Re: 6502 cycle-level instruction detail

I used to use 64doc.txt for cycle details. Very outdated now though, and it only really covered the NMOS chips.
by SarahWalker
Wed Oct 14, 2020 10:38 am
Forum: programming
Topic: [SOLVED] Noob question about sound on Beeb
Replies: 9
Views: 341

Re: Noob question about sound on Beeb

Is the OS IRQ handler still running? If so you might want to move the write to $fe43 in between sei/cli as the OS IRQ handler may well end up overwriting this. I'd also suggest writing the sound data to $fe4f rather than $fe41 as this avoids accidentally acknowledging interrupts. Also if you're poki...
by SarahWalker
Fri Oct 09, 2020 7:54 am
Forum: 32-bit acorn hardware
Topic: A310 restoration
Replies: 116
Views: 7487

Re: A310 restoration

I can't remember if screen memory starts at 0 or 0x8000. It's one of the two.

IC84/85 would look to be correct.
by SarahWalker
Thu Oct 08, 2020 9:45 pm
Forum: 32-bit acorn hardware
Topic: Upgrading VRAM 1MB->2MB
Replies: 26
Views: 2043

Re: Upgrading VRAM 1MB->2MB

RISC OS puts the CPU pagetables in VRAM briefly during bootup, which would explain failure to boot if the VRAM is good enough to be detected but otherwise has issues on the CPU port.
by SarahWalker
Thu Oct 08, 2020 9:41 pm
Forum: 32-bit acorn hardware
Topic: A310 restoration
Replies: 116
Views: 7487

Re: A310 restoration

Video fetch is limited to the first 512kb on a MEMC machine. From the photos you've posted I'd guess the issue is in the 128kb-256kb range, hence MODE 28 (which is 300kb) occupies the faulty region and allows the rest of the system to actually work. This unfortunately doesn't help narrow down the fa...
by SarahWalker
Sun Sep 27, 2020 10:31 am
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Ran some POVRay tests yesterday. Results are not at all surprising. If anyone is bored enough to reproduce, I used POVRay 2.2 as that's what I had to hand, with the command line "povray +Iscenes.level3.car +Oout/tga +W160 +H120". R260, ARM3 at 26 MHz + FPA10 - 11m48s (ylib version was 9m26s) A5000a,...
by SarahWalker
Thu Sep 17, 2020 12:52 pm
Forum: 32-bit acorn hardware
Topic: A5000 repairs
Replies: 57
Views: 1580

Re: A5000 repairs

I wonder if there's some special magic on the A4 (something else on the I2C bus maybe?) Battery Management Unit is also present on the I2C bus on the A4. Technically it shouldn't be affecting accesses to the (absent) CMOS RAM chip... On the four machines I've seen CMOS RAM chip failure on (2 A3000s...
by SarahWalker
Wed Sep 16, 2020 6:04 pm
Forum: 32-bit acorn hardware
Topic: A5000 repairs
Replies: 57
Views: 1580

Re: A5000 repairs

Should emphasise that delete-power-on will not work if the CMOS RAM chip is faulty, as is quite likely.
by SarahWalker
Sun Sep 13, 2020 10:29 pm
Forum: 8-bit acorn software: classic games
Topic: Electron enhanced versions?
Replies: 13
Views: 1169

Re: Electron enhanced versions?

Repton TLR takes advantage of sideways RAM to provide a full screen display. Probably more modern than you're asking for though. I have an Electron connected to a Plus 1 with an AP6 board installed (original PRES version). I have two static RAM chips installed. A GoSDC card makes use of one of thes...
by SarahWalker
Sat Sep 05, 2020 7:05 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Yes, if you're willing to burn the space in cache. Edit: To be more specific : If you're not going to use the data again anytime soon, then yes, align to 8 words and try to read 8 words at a time if possible (as this will prevent the CPU being halted during the cache line fetch). If you _are_ likely...
by SarahWalker
Sat Sep 05, 2020 6:39 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

!SICK's memory results were annoying me enough for me to do some digging. It's using 12-word LDM/STMs for memory benchmarking, which provoke some suboptimal behaviour in ARM710 and (to a lesser degree) StrongARM, which have 8-word cache lines. For all the other CPUs (which have 4-word cache lines) i...
by SarahWalker
Sat Sep 05, 2020 2:38 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Added in the O/C A3020 results, fleshed out the Mico a bit, also added !SICK main memory results (though IIRC !SICK applies a fudge factor so these shouldn't be taken as gospel).
by SarahWalker
Tue Sep 01, 2020 9:37 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Yep, that's the correct border size. What's the performance in low detail mode? (press F5) You shouldn't need to modify any obey files, add '-timedemo demo1' in the 'Others' field under miscellaneous options. For the curious, Doom timedemo performance is (gametics / realtics) x 35. For the sake of f...
by SarahWalker
Mon Aug 31, 2020 8:01 am
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

Updated first post. I also tracked down a RISC OS 3 ARM2 w/MEMC1a Whetstone result to replace the blatantly rigged old-FPemulator-running-from-RAM A3000 result. Given that FPemulator would have been running from ROM it's not entirely surprising that ARM2 and ARM250 give basically the same result on ...
by SarahWalker
Mon Aug 31, 2020 7:34 am
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

My A3000 is running RISC OS 2 with an older FPemulator, so the FP results there probably aren't directly comparable with RISC OS 3 machines.

Cheers for the A420 results btw, interesting to see the relative impacts of CPU/memory speed. Just to check, this was in MODE 12?
by SarahWalker
Sun Aug 30, 2020 9:43 pm
Forum: 32-bit acorn software: other
Topic: Benchmarks
Replies: 20
Views: 1055

Re: Benchmarks

!SICK and CLOCKSP are readily available online, Doom+ can be got from your local dealer...

I've attached the Reach benchmarks. Both will run then print an execution time in centiseconds. Galaxy framerate is 436 / (centisecond execution time / 100), tunnel is 896 / (centisecond execution time / 100).

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