Search found 1177 matches

by SarahWalker
Tue Sep 17, 2019 5:11 pm
Forum: hardware
Topic: Video timing on Acorn Electron
Replies: 2
Views: 135

Re: Video timing on Acorn Electron

From initial tests it looks to me like interleaved RAM access between CPU and ULA. Correct, the ULA will alternate RAM accesses between CPU and video/refresh cycles. So in a 128 cycle scanline the CPU will run for 64 cycles, resulting in 1 MHz, with 40 cycles of active display and 24 of blanking. T...
by SarahWalker
Fri Sep 13, 2019 7:38 pm
Forum: hardware
Topic: MEMC1A timeline and documentation
Replies: 9
Views: 797

Re: MEMC1A timeline and documentation

Bit of a bump, but I've been reworking the ARM/MEMC timing in Arculator, and I feel the need to rectify my statement above that 'MEMC1a and MEMC1 w/o workarounds perform the same'. I've identified three performances differences between MEMC1 and MEMC1a systems, only one of which is the result of a w...
by SarahWalker
Wed Sep 11, 2019 1:15 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 93
Views: 5183

Re: MAME: Click (and other large ROMs)

Looks like it initially writes 0f to 8000 and checks if it can immediately read it back, failing if it can. Then it goes into a loop of lda 8000 / cmp 8000 / bne is_empty, ie it's testing that the value changes more over time. So for this to work you'd effectively have to return random data on readi...
by SarahWalker
Sat Sep 07, 2019 8:42 pm
Forum: archive requests
Topic: Archimedes Podule ROMs
Replies: 1
Views: 98

Re: Archimedes Podule ROMs

I've got dumps of the podules mentioned in viewtopic.php?f=30&t=17833.
by SarahWalker
Thu Sep 05, 2019 7:50 pm
Forum: emulators
Topic: Arculator podule API v1.0
Replies: 7
Views: 500

Re: Arculator podule API v1.0

In case there are multiple ICS designs, mine says '(C) BE 1992 IDE I/F V5' on the PCB, and '(C) 1993 ICS Ltd IDE1V5 3V10' on the EPROM. The IDEFS implementation also seems to be somewhat fancier than the normal bog standard one, offering partitioning and password protection among other things.
by SarahWalker
Thu Sep 05, 2019 7:46 pm
Forum: emulators
Topic: Arculator podule API v1.0
Replies: 7
Views: 500

Re: Arculator podule API v1.0

Assuming that IanS's interfaces are following what ZIDEFS thinks an ICS interface is, this is the expected memory map (from https://stardot.org.uk/forums/viewtopic.php?f=16&t=15205) : +0x0000 - 0x1FFF ROM window (2 KB) +0x2000 ROM page register +0x3000 IDE reg 0 +0x3004 IDE reg 1 +0x3008 IDE reg 2 +...
by SarahWalker
Wed Sep 04, 2019 5:28 pm
Forum: emulators
Topic: Arculator podule API v1.0
Replies: 7
Views: 500

Re: Arculator podule API v1.0

Not sure how adaptable ZIDEFS is; ideA (or at least the podule I own) has a somewhat different memory map to the modern IDE podules. As does the RISC Developments podule.
by SarahWalker
Tue Sep 03, 2019 7:52 pm
Forum: emulators
Topic: Arculator podule API v1.0
Replies: 7
Views: 500

Re: Arculator podule API v1.0

If a suitable podule with the correct address map supporting 4 drives is written, yes. That's not really a function of the API though.
by SarahWalker
Tue Sep 03, 2019 7:24 pm
Forum: emulators
Topic: Arculator podule API v1.0
Replies: 7
Views: 500

Arculator podule API v1.0

I've posted below the podule API currently implemented by the in-progress next version of Arculator, should anyone be interested (I think this is most likely to be flibble and possibly Phlamethrower); it would be nice if this could be used cross-emulator/platform. I think I'm unlikely to change much...
by SarahWalker
Tue Aug 27, 2019 9:18 pm
Forum: hardware
Topic: Armadillo A448 Sampler/MIDI podule
Replies: 6
Views: 314

Re: Armadillo A448 Sampler/MIDI podule

It's entirely possible it's the same ROM. Or at least hopefully the sampling hardware is the same on both podules!
by SarahWalker
Sun Aug 25, 2019 1:54 pm
Forum: hardware
Topic: Armadillo A448 Sampler/MIDI podule
Replies: 6
Views: 314

Armadillo A448 Sampler/MIDI podule

While digging through hardware looking for stuff to emulate in Arculator, I found an Armadillo A448 Sampler/MIDI podule : http://chrisacorns.computinghistory.org.uk/32bit_UpgradesA2G/Armadillo_A448.html Both of the podules pictured on Chris's Acorns have ROMs fitted, but the ROM socket is empty on m...
by SarahWalker
Sat Aug 24, 2019 9:29 am
Forum: off-topic
Topic: Merry Christmas
Replies: 4
Views: 442

Re: Merry Christmas

Seems pretty ironic for this topic to pop up today given the current weather in the UK
by SarahWalker
Tue Aug 20, 2019 4:02 pm
Forum: other vintage computer hardware, software and games
Topic: Hardware for retro 3d stuff
Replies: 2
Views: 163

Re: Hardware for retro 3d stuff

Amiga has bitplanes so you may well spend most of your time worrying about chunky to planar conversions. Cpu wise an a1200 with fast ram should be similar speed to an arm2. The a4000 will be faster, but you're stuck with a crap palette in 256 colour modes - not very good for gouraud shading! If you ...
by SarahWalker
Sun Aug 11, 2019 8:12 pm
Forum: software
Topic: Unreleased games
Replies: 42
Views: 3661

Re: Unreleased games

Randomly found a screenshot of Frak 3 in The One - issue 15 (December 1989), page 32. The text also mentions Archimedes 3D Pool as in a 'state of limbo'.
by SarahWalker
Tue Jul 09, 2019 5:04 pm
Forum: hardware
Topic: What became of the 80186 podule?
Replies: 3
Views: 367

Re: What became of the 80186 podule?

80186 systems aren't IBM compatible, so this may have been canned due to lack of software compatibility.
by SarahWalker
Tue Jul 09, 2019 5:01 pm
Forum: software: classic games
Topic: Volcano on the Elk?
Replies: 16
Views: 988

Re: Volcano on the Elk?

There's also some VIA pokery going on; Volcano won't actually run unless expired timers return &ff. So it basically runs on the Elk by accident :)
by SarahWalker
Thu Jun 27, 2019 5:31 pm
Forum: hardware
Topic: R260... Daddy is going to mess with it again..
Replies: 13
Views: 778

Re: R260... Daddy is going to mess with it again..

Arculator built from recent source supports RISCiX.
by SarahWalker
Sun Jun 23, 2019 8:08 am
Forum: software
Topic: New demo - Horizon
Replies: 6
Views: 582

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: 221

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: 403

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: 596

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: 596

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: 596

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: 804

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: 804

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: 804

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: 678

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.