Search found 123 matches

by ThomH
Fri May 25, 2018 2:45 pm
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 62
Views: 21722

Re: Clock Signal — an Oric emulator for macOS and Linux

I can cobble together a DSK to WOZ converter from what's already in the emulator, though it might make sense to take a moment to simplify it a little. Apologies for NIB still being read-only, by the way; when I became aware of the Microdisc regression I just tied up some loose ends and released, and...
by ThomH
Fri May 25, 2018 3:11 am
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 62
Views: 21722

Re: Clock Signal — an Oric emulator for macOS and Linux

I've made a hasty new release to correct a regression in Microdisc support. Also included: initial write support from 8DOS to DSK and WOZ images. For the time being the whole emulation is a little slower in support of that whenever the 8DOS drive is being accessed, read or write, but I've a fix for ...
by ThomH
Tue May 22, 2018 3:55 pm
Forum: 6502 assembly coding
Topic: Horizontal HIRES and Text scrolling code needed.
Replies: 33
Views: 15972

Re: Horizontal HIRES and Text scrolling code needed.

If you could afford a 64-byte lookup table where the value at binary offset `abcdef` is `a01bcdef` and the use of all three registers then you can shave two cycles over the explicit cmp/and/ora: LDX line, Y ; load current pixel contents into X; guaranteed to be of the form '01ab cdef' LDA table-64, ...
by ThomH
Tue May 22, 2018 3:10 pm
Forum: 6502 assembly coding
Topic: 6502 flags C, N, Z, V and tests
Replies: 7
Views: 162

Re: 6502 flags C, N, Z, V and tests

Given that `LDA`, `LDX` and `LDY` all set N and Z and all work as immediate instructions, if you have a register you don't mind overwriting then you can set N that way, and if you're setting N=0 then you can also pick a value for Z. It's two cycles, so it costs the same as a `SEC`, etc. E.g. LDX #$8...
by ThomH
Mon May 21, 2018 5:12 pm
Forum: 6502 assembly coding
Topic: Pseudo 3D Starfield
Replies: 3
Views: 5398

Re: Pseudo 3D Starfield

In Elite stars have a current (x, y, z). They are currently plotted directly at (x, y). z isn't a factor in plotting. To move a star closer by a delta 'd', the engine computes offset = d/z. It then subtracts that offset from the stored z, and adjusts (x, y) to (x', y') = (x, y) * (1 + offset). So it...
by ThomH
Mon May 21, 2018 4:18 pm
Forum: 6502 assembly coding
Topic: 6502 flags C, N, Z, V and tests
Replies: 7
Views: 162

Re: 6502 flags C, N, Z, V and tests

In case it helps to offer any exposition as to `CLV`, 6502s have a dedicated input pin, SO, which when asserted will s et o verflow. It's there in case the hardware design requires a low-latency polling input: CLV ; clear V in preparation to wait... .loop BVC loop ; repeat until V is set That gets y...
by ThomH
Wed May 16, 2018 2:43 pm
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 62
Views: 21722

Re: Clock Signal — an Oric emulator for macOS and Linux

* doesn't affect the Oric. But, essentially, nowadays if you insert a piece of media for which the correct machine or hardware configuration cannot be determined a priori, the proper machine and configuration will be found empirically. E.g. if you provide a 16kb file with a .bin extension and the e...
by ThomH
Wed May 16, 2018 2:53 am
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 62
Views: 21722

Re: Clock Signal — an Oric emulator for macOS and Linux

I've released a new version to GitHub . Most interesting features: Pravetz 8DOS support (read-only at present); text pasting is unbroken for the Mac port; and text pasting is faster and more accurate on both the Mac and SDL. For 8DOS, DSK or WOZ files are supported. NIBs are also implemented but I'm...
by ThomH
Tue May 15, 2018 2:58 pm
Forum: Emulators
Topic: JOric
Replies: 84
Views: 4725

Re: JOric

(Of course, contacting MS would not hurt, if they care to answer I suspect they would confirm the hypothesis I just laid down here.) Not to mention that owning a licence does not necessarily mean owning a licence in perpetuity, or owning an assignable licence. Just as with PC-DOS, Microsoft may hav...
by ThomH
Mon May 14, 2018 11:35 pm
Forum: Emulators
Topic: JOric
Replies: 84
Views: 4725

Re: JOric

I can't speak as to the manuals but the Commodores identify themselves as running Commodore BASIC, and although the Apple version of Microsoft BASIC is often called 'Applesoft', nothing identifying is printed at all. So I'm not sure the absence of the word Microsoft necessarily means anything. It'd ...
by ThomH
Mon May 14, 2018 5:18 pm
Forum: Emulators
Topic: JOric
Replies: 84
Views: 4725

Re: JOric

I'm actually a bit confused about that second quote as it seems to imply that Tangerine was a company and that 'Oric' was another company rather than a product of Tangerine, which held a BASIC licence. The Register's version sounds a lot more plausible: 1983 isn't just the launch year of the Oric, i...
by ThomH
Wed May 09, 2018 3:02 pm
Forum: Games
Topic: Wolfenstein / DOOM for Oric : has this been done?
Replies: 19
Views: 1357

Re: Wolfenstein / DOOM for Oric : has this been done?

Here's a longer video of the same title by somebody other than me, not implicitly about proving that they've fixed a counter placement bug: [media]https://www.youtube.com/watch?v=J203nk_OxQs[/media] It was also available with completely different graphics for the Atari 400/800/etc, with the faster p...
by ThomH
Wed May 09, 2018 2:35 pm
Forum: Technical questions
Topic: 8DOS: overlay RAM control?
Replies: 6
Views: 487

Re: 8DOS: overlay RAM control?

I tried only 130 and, from memory, probably 210; neither seemed to proceed all the way back to the BASIC prompt. But it wasn't particularly systematic testing. I guess that most likely I've messed up my implementation of 0380–0383 as all DOSes to count down and then get stuck, so maybe they're inadv...
by ThomH
Wed May 09, 2018 4:05 am
Forum: Technical questions
Topic: 8DOS: overlay RAM control?
Replies: 6
Views: 487

Re: 8DOS: overlay RAM control?

Sorry, it's a gross digression, but having attempted to implement an emulation of the scheme as above, I see as per this video; the machine hangs at the end — I can wait indefinitely and that final frame will be unchanged: [media]https://youtu.be/rRGz0Uoo9QE[/media] So my relevant follow-up question...
by ThomH
Wed May 09, 2018 3:40 am
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 35
Views: 2436

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

Well, the sneak preview gossip from my emulator is attached. I've not implemented any track skew, but still see the results as attached from your mapper.dsk so is it possible that Oricutron just doesn't preserve disk position when stepping tracks? i.e. each swing of the head magically resets the dis...