Search found 149 matches

by ThomH
Mon Apr 30, 2018 7:15 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 39496

Re: Merging video output?

Tom: You should probably read back the entire thread :) I have to admit that I find it very hard to think of what would have a relevant response to "the only difficulty become to make the four cpus start exactly at the same time" given that it's also true that "the processors are not a problem at a...
by ThomH
Mon Apr 30, 2018 6:41 pm
Forum: Emulators
Topic: JOric
Replies: 92
Views: 23621

Re: JOric

Yep: PAL is idiomatically taken to have 52μs of visual information horizontally and be 287.5 lines vertically. Given the 4:3 ratio, a perfectly-square pixel would have to last (3/4) * (52/287.5) ~= 0.135652173913μs. The Oric outputs pixels for 40μs and includes 240 of them. So each actually lasts 40...
by ThomH
Mon Apr 30, 2018 2:44 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 39496

Re: Merging video output?

If you're going with one machine to produce R, one for G, one for B (?) then why not just replace the colour ROM with one that's plain grayscale, no colour subcarrier at all, and combine the composite outputs? I don't know if it's so obvious as not to require statement, but the substantial other pos...
by ThomH
Mon Apr 30, 2018 2:27 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 35
Views: 8806

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

I've created simple utility which prints the order of sectors in each track. It's based on the loading routine. The sector number is extracted from the address field. I expected to see some interleave but the result shows natural order ... which puzzles me :shock: . I always try to avoid reading ot...
by ThomH
Fri Apr 27, 2018 4:53 pm
Forum: Technical questions
Topic: Merging video output?
Replies: 86
Views: 39496

Re: Merging video output?

So, I did some testing, playing with one idea at a time. This time the idea was: Just use three Orics, each one is in charge of one component (so one only display red, one only display green, one only display blue) and just use these as inputs. ... Plenty of other possibilities to explore, but it's...
by ThomH
Fri Apr 27, 2018 2:55 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 35
Views: 8806

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

Thanks for the rich info about NIB and WOZ image formats, ThomH! The minimum I wish to add to Oricutron is support of any sector interleave. Else I think it's not worth to add half- and quarter-track positioning ability and all that stuff which in the Apple's world is used for different protection ...
by ThomH
Thu Apr 26, 2018 8:40 pm
Forum: Technical questions
Topic: 8DOS: overlay RAM control?
Replies: 6
Views: 2173

Re: 8DOS: overlay RAM control?

I guess the engineers at Pravetz really internalised the idea of soft switches! So you can put almost any other Apple II card into the other slots and expect to be able to talk to it? Was there any software support for that? Presumably subject to limitations, which I would guess(?) to include: the 2...
by ThomH
Thu Apr 26, 2018 6:29 pm
Forum: Technical questions
Topic: 8DOS: overlay RAM control?
Replies: 6
Views: 2173

8DOS: overlay RAM control?

Documentation seems to be extremely slender on 8DOS, so here's what I currently think I know. From iss I've learnt the fundamentals necessary to support 8DOS v1: the boot ROM is visible from $320 to the end of that page; and the Disk II controller registers are exposed from $310. Per the Fastload so...
by ThomH
Thu Apr 26, 2018 2:35 pm
Forum: Emulators
Topic: JOric
Replies: 92
Views: 23621

Re: JOric

I'd also vote in favour of maintaining the proper aspect ratio, especially when you consider the pixel densities of modern Android devices, and the direction that pixel density continues to head. In Clock Signal I apply a discreet lowpass filter to suppress some of the resulting aliasing; have you c...
by ThomH
Wed Apr 25, 2018 9:08 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 35
Views: 8806

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

The emulation in Oricutron is very far from perfect, I added it to be able to run DOS-8D and some interesting old software and until now there was no demand for something better, but this will change and I think to add NIB support, which will provide as side effect the possibility to use any interl...
by ThomH
Thu Apr 05, 2018 3:49 pm
Forum: Emulators
Topic: Oricutron and Mac Sierra and High Sierra
Replies: 15
Views: 7119

Re: Oricutron and Mac Sierra and High Sierra

and you can virtualise old versions of OS X going back to 10.4 which was the first version on this side of the Intel transition. In my (somewhat limited) experience, running OSX in a VM was good enough for normal applications, but it gave terrible performance for games or anything relying heavily o...
by ThomH
Thu Apr 05, 2018 3:01 pm
Forum: Emulators
Topic: Oricutron and Mac Sierra and High Sierra
Replies: 15
Views: 7119

Re: Oricutron and Mac Sierra and High Sierra

Sorry, to be clearer about prejudice: my day job for almost a decade was iOS development, both in iOS-first organisations where everything tended to be smooth and easy and in the furthest possible thing you can get from an iOS-first organisation, where there was a natural desire to plug iOS developm...
by ThomH
Tue Apr 03, 2018 3:51 pm
Forum: Emulators
Topic: Oricutron and Mac Sierra and High Sierra
Replies: 15
Views: 7119

Re: Oricutron and Mac Sierra and High Sierra

It might say more about my abilities than anything else, but I find that keeping up to date with Xcode is a worthwhile aim in itself just because the surrounding tooling is always improving. E.g. the latest version of the runtime analysis tools pointed out the undefined behaviour in (heavily simplif...
by ThomH
Sat Mar 31, 2018 9:39 pm
Forum: Emulators
Topic: JOric
Replies: 92
Views: 23621

Re: JOric

I think most fairly, it is designed to be memory mapped, but to a CP1610, which has a multiplexed bus. So the extra level of indirection on most machines is implemented just because it's the easiest way of dealing with that.
by ThomH
Thu Mar 29, 2018 6:50 pm
Forum: Emulators
Topic: JOric
Replies: 92
Views: 23621

Re: JOric

Unfortunately I don't think there's a quick shortcut to test disk titles because many of them, if not most, talk to the controller directly. I would dare imagine you can implement your WD to jump directly to any requested sector and stream its bytes exactly as the CPU reads them but the Oric disk fi...