forum.defence-force.org

My emulator implements real timing* but isn't quite ready yet; in a few weeks (or so) I or anybody else with a Mac can probably perform some basic timing tests if that'd be helpful. Sorry for the vague future offer — I thought maybe it was a bit more helpful to say something while the topic is activ...

The numbers originally proposed, even if I hadn't mixed up multiplying by 40 and multiplying by 64, were predicated on a 260-line 60Hz frame. It turns out it's 264 lines. So the original arithmetic is based on false accounting, though the premise is still solid: leave a 60Hz attribute visible in a s...

Yes, perfect, thanks! So it's call and response: the 1793 sets the HLD output upon receiving a command and proceeds only once the HLT input is set, for which the Microdisc has an LS123 and another part whose number I can't quite make out but which I assume together amount to: wait a fixed period. HL...

I'm specifically having difficulty chasing up the logic behind the HLD (head load, presumably?) pin, which per the Microdisc schematic is wired directly to the drives' motor on. Is there a spin-up sequence as there is when the 1770 and 1772 changes the motor on line (i.e. enable signal, wait for six...

312 and 264 are even better: the greatest common divisor of the two is 24 so unless I'm having a complete failure of logic you should be able to box yourself in to a 24-line period?

Frustratingly, three years later, the site linked to appears no longer to exist (it serves blank pages only), was not caught by archive.org and the only other archive I can find is missing quite a few issues when you try to click through — including issues 80 and 81 as I think referred to above. I g...

Oh! And! I forgot to make my boast! Screenshots as below. As I am emulating an unexpanded Atmos, I'm assuming I'm supposed to compare my "Normal ORIC boot with IRQ" to that of the Atmos screenshot rather than to the Pravetz. If that's a correct understanding and not a desperate cherry-pick...

A quick [repeat] post to highlight a new release . The primary fix is to my interpretation of the TAP file format. Which fixes Stormlord and a bunch of other things. I have read that there is meant to be a gap between header and data but due to an off-by-one error was recognising the 00 that comes b...

Thanks! That's helped a lot. Of the platforms I happen already to know about, that's actually really close to the way the Vic-20 does it: on that platform a 1-bit version of the input wave is connected to a VIA control line to catch transitions in one direction only, counted against that VIA's secon...

THE IDEA So you got it: no special routines here, just an optimized tape signal. It was based on a study of the ROMs. The standard signal, in FAST, codes a bit "1" by a 416 microseconds sinusoid (2 x a 208µs duration), and a "0" by a 624µs sinusoid (3 x 208µs). When reading a ta...

Indeed! However I cannot remember my screen getting out of sync that way, it simply showed some garbage in the middle. What a screen does with an improper input is undefined, so I think a bunch of them act differently — e.g. my actual '90s-era TV just cut away to blue. So I just picked any one auth...

I've uploaded a new build ; the best thing about it is that I've implemented automatic typing and fast loading so that those titles that work can be launched directly from the Finder — just double click and run. Performance should also have taken a step in the right direction. A fun screenshot to de...

On a real floppy disk there's no reason you need to store sectors in order. If the problem is as per the guesses, you could just put them on the surface as sector 0, sector n/2, sector 1, sector n/2+1, etc. The FDC reads each sector header as it comes and each header contains the full sector address...

I'm late to everything, but following on from the way the Spectrum's Cobra works, wouldn't it be possible to keep the Oric in text mode, then for each 8x8 tile define 16 possibilities: 0–5 = the tile internally rotated by 0–5 pixels; 6–11 = partial parts of the tile creeping in from the right hand s...

Could this method work on text mode too? Will this software sync be lost if done in HIRES, then switch to TEXT or viceversa? I guess that it won't as long as you don't play with the 50/60Hz switch... Yes, it should also work in text mode. Example pseudocode: establish 50Hz graphics mode, wait at le...