Search found 238 matches

by ThomH
Wed Jan 22, 2020 11:46 pm
Forum: Technical questions
Topic: Jasmin time
Replies: 33
Views: 24568

Re: Jasmin time

Have you tested the clock signal on the Jasmin? Just as a random guess, but has it possibly drifted into overclocking territory? That'd directly affect the speed it wanted data when writing, but might not be sufficiently far to cause an issue when reading. I guess you could also read track after wri...
by ThomH
Wed Jan 22, 2020 7:14 pm
Forum: General Discussion
Topic: New Guy here from USA
Replies: 14
Views: 7769

Re: New Guy here from USA

If you can handle either Bulgarian or ROM swapping (is it socketed?), don't rule out the Pravetz 8D. It seems to be much more readily available than the Atmos, and cheaper too. It's a full Oric clone, with no hardware differences documented that I'm aware of. Right now I see six for a search on ebay...
by ThomH
Wed Jan 22, 2020 3:58 am
Forum: General Discussion
Topic: New Guy here from USA
Replies: 14
Views: 7769

Re: New Guy here from USA

I'm an ex-pat, so it counts for less, but that makes at least two of us in the USA. I am located in Northern California... and you? TJ I was in the Bay Area when I first moved over, but nowadays I'm in New York. So on the one hand I sort of miss it during winter, but on the other I enjoy actually h...
by ThomH
Tue Jan 21, 2020 9:34 pm
Forum: General Discussion
Topic: New Guy here from USA
Replies: 14
Views: 7769

Re: New Guy here from USA

I'm an ex-pat, so it counts for less, but that makes at least two of us in the USA.
by ThomH
Sun Jan 19, 2020 4:18 am
Forum: General Discussion
Topic: SCSI harddrives...
Replies: 7
Views: 4957

Re: SCSI harddrives...

If it's any help, SCSI command 4 is 'format unit' but the ECMA spec explicitly says: "The FORMAT UNIT command ensures that the medium is formatted so that all data blocks can be accessed. There is no guarantee that the medium has or has not been altered." So to my reading, an individual SC...
by ThomH
Fri Jan 17, 2020 3:53 pm
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 170
Views: 159070

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

actually, follow-up query on the Jasmin: if you can select arbitrarily many then how do you deselect drives? Drive 0 -> 0x3FC, Drive 1->0x3FD, Drive 2->0x3FE, Drive 3->0x3FF To select a drive write 1 to the corresponding address and 0 to deselect. Cool, thanks! I'm going to hold back on iss's sugge...
by ThomH
Fri Jan 17, 2020 4:53 am
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 170
Views: 159070

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

Most importantly: the BD-DOS spin-down issue is 'fixed' (in the sense: I've taken a different guess at the sort of RDY it's expecting from the drive) in a new release . Otherwise: Sync 60Hz is out of sync because it is genuinely out of sync. The simulated Oric produces a real 1d video signal with ap...
by ThomH
Fri Jan 17, 2020 4:01 am
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Re: Is BD-DOS lost to time?

Some more quick observations on this, relevant to yesterday's botched release: The boot ROM performs: seek to 0, read boot sector, check for errors (including drive not ready). Somewhere between then and the command prompt, the logic changes to: (i) issue a force interrupt and check for drive not re...
by ThomH
Thu Jan 16, 2020 6:15 am
Forum: Emulators
Topic: Clock Signal — an Oric emulator for macOS and Linux
Replies: 170
Views: 159070

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

It's late in the day, so I'll be quick: I've uploaded a new release that takes a shot at Byte Drive 500 emulation. EDIT: it appears there’s a dangling bug with drive spin-up on the Byte Drive; it’ll happen the first time but not subsequently. Either issue all of your DOS commands really quickly, bef...
by ThomH
Thu Jan 16, 2020 4:59 am
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Re: Is BD-DOS lost to time?

Further notes, probably the final for today: The boot sector accesses $0311 and $0317 only. It has a check for BASIC 1.0 (at 04a5–04aa in the disassembly above). Therefore either $0311 or $0317 must disable the disk ROM, and the other must do something else. It seems safe to respond to either and ig...
by ThomH
Thu Jan 16, 2020 2:37 am
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Re: Is BD-DOS lost to time?

Fabrice's notes are a little vague on what accesses other than to the WD do (at least when read through automated translation), so I am brute-forcing the problem, with slightly weird results. Per Fabrice, the accesses other than to the WD are probably to Apple/Pravetz-esque soft switches. I seemed t...
by ThomH
Tue Jan 14, 2020 11:36 pm
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Re: Is BD-DOS lost to time?

Fantastic, amazing! I'm sure we can figure it out from the ROM and a disk image. Given that the intention of the Byte Disk was to be the disk drive for every platform, showing only the relevant files on each, it might also be fun to try to figure out the on-disk format. There's possibly non-Oric ver...
by ThomH
Tue Jan 14, 2020 9:18 pm
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Re: Is BD-DOS lost to time?

Probably the actual easiest thing for answering these sort of questions for myself would be to learn French.

Pulling on that thread there seem to be articles in both CEO-Mag #154 and 155. So a quick subscription to that is probably the best plan.
by ThomH
Tue Jan 14, 2020 4:11 pm
Forum: Operating systems, utilities and other serious software
Topic: Is BD-DOS lost to time?
Replies: 94
Views: 66745

Is BD-DOS lost to time?

BD-DOS, for the Byte Drive 500, is mentioned on the Wikipedia Oric page and reported on non-Oric forums as though it were primarily an Oric device. It appears in photographic form in CEO-Mag #272.

Has anyone preserved BD-DOS and/or any technical information for potential emulation?
by ThomH
Mon Jan 13, 2020 4:56 pm
Forum: Tape and floppy disk converters
Topic: Track reading (Sedoric / FDC)
Replies: 62
Views: 69621

Re: Track reading (Sedoric / FDC)

I've just discovered possibly the most egregious of false sync situations: On track 41, the ID mark for any normally-written floppy will be [sync] A1 * 3, FB 29. The final nine bits of that sequence are 000101001, which MFM encodes to: 01 01 00 10 00 10 01 00 1x, i.e. the C2 sync followed by 00 1x. ...