OSI floppy and IDE (ATA) disk

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__leeeeee
Posts: 8
Joined: Mon Dec 05, 2011 1:49 am

OSI floppy and IDE (ATA) disk

Post by __leeeeee » Mon Dec 05, 2011 2:22 am

I've been looking into the workings of OS-65D V3.0 with the plan to add an 80 track floppy to my Compukit UK101.

The OSI DOS seems to be a bit of a bodge, lots of self modifying code and branches to patches, and it would seem just as easy to add an IDE device as a floppy drive.

The only real change needed to support this would be an update to the disk boot routine in the monitor ROM to support the new hardware.

Any thoughts on what sort of filesystem to implement.

Anyone have a listing for OSI disk BASIC so it could be patched to support the IDE device.

Lee.

__dave
Posts: 19
Joined: Mon Dec 05, 2011 1:48 am

Re: OSI floppy and IDE (ATA) disk

Post by __dave » Mon Dec 05, 2011 2:23 am

I would like to do the same thing for my superboard. I have a couple of PEEK(65) journal articles that detail how to interface modern drives, including high-density 3.5" drives, to the OSI. The OS changes are minimal. I will make an effort to scan them and post them this week.

I think that the disk BASIC uses the OS for all disk access, and hopefully would need no modification. The same generous person who sent me the PEEK(65) journals also sent me an annotated listing of OS65D, which may be helpful in understanding how to modify for IDE, if desired. The PIA from the disk board could be re-purposed for an 8-bit IDE interface. I think that the resources at 6502.org could be helpful.

__leeeeee
Posts: 8
Joined: Mon Dec 05, 2011 1:49 am

Re: OSI floppy and IDE (ATA) disk

Post by __leeeeee » Mon Dec 05, 2011 2:24 am

I've mostly finished disassembling OS-65D V3.0 but there still seems to be chunks of orphaned code and accesses that don't make sense such as writes to $FBxx, $DFxx and others. I'd like to compare with the listing you have.

I have a proven design for an IDE interface that allows 16 bit access and use of all 512 bytes per sector. OS-65D seems to allow any sector size from $100 to $800 bytes so the more that can be transfered at once the better. Also I hate wasting half a drive, even if it is gigabytes in size. 8^)=

I could do with more info on the disk BASIC, all I have so far is the binary on a disk (and in an image of that disk) but it doesn't seem to work correctly. This may be because I'm trying to run it on a Compukit with Cegmon and not on an OSI CPU600.

I've been looking for OS-64D V3.3 which was allegedly ported to the Elektor 6502 SBC but, apart from a disk image that turned out to be another V3.0, I've not found anything.

Lee.

__dave
Posts: 19
Joined: Mon Dec 05, 2011 1:48 am

Re: OSI floppy and IDE (ATA) disk

Post by __dave » Mon Dec 05, 2011 2:25 am

I've scanned Peek[65] vol. 7 nr. 12, which has an article on interfacing standard PC 5.25" HD floppies to the OSI. A subsequent article discusses the small ajustments for 3.5" floppies, including OS65D parameter fixes.

It seems that the images I have also contain the string "OS-65D V3.0". I do have disassembly listings for v3.2 and v3.3, and both of these contain the ID string "v3.0", so your image may still be v3.3 despite the ID string. I would have to investigate further. I have a disk version of 3.3, if I can revive my 5.25" drive to read it.

Dave

__leeeeee
Posts: 8
Joined: Mon Dec 05, 2011 1:49 am

Re: OSI floppy and IDE (ATA) disk

Post by __leeeeee » Mon Dec 05, 2011 2:26 am

I've grabbed that copy of PEEK[65] ta much. There seems to be very little of that sort of material available on the net. I know most of my books and notes from then have long since gone.

Having checked through my OSI boot images and disks again they are all the same version of OS-65D. Be this V3.0, as the version string states, or a later version remains to be discovered.

Devling further into the workings of OS-65D it seems parts are actually patches for parts of disk BASIC. It seems you don't need a high level language to write spaghetti code.

Lee.

__dave
Posts: 19
Joined: Mon Dec 05, 2011 1:48 am

More disk interfacing info

Post by __dave » Mon Dec 05, 2011 2:27 am

I just posted vol 7 nr 9 of Peek(65) which has another article on interfacing standard drives, with much more detail on signals, wiring, data separator and motor control circuits, and 65D mods. It's in the Journals section. I'll try to get the annotated (v3.2) OS-65D listing scanned over the next week or two.

__dave
Posts: 19
Joined: Mon Dec 05, 2011 1:48 am

Re: OSI floppy and IDE (ATA) disk

Post by __dave » Mon Dec 05, 2011 2:27 am

done.

__Mark
Posts: 2
Joined: Mon Dec 05, 2011 1:50 am

OS65D images

Post by __Mark » Mon Dec 05, 2011 2:29 am

I've placed a few disk images with OS65D for the C1 on my web page at http://my.execpc.com/~mspankus/osi/osi.html These came from labeled OSI disks, and even though you'll see a "V3.0" when you disassemble the code, it's actually V3.3. I also have one disk with V3.1 in the archive. (Dave feel free to move it here.) I can also dig up a 65D image for the 8" drive if needed. It'll work better on a 3.5" drive I suspect.

$FB0x could be a S1883 UART on the old 400 series boards (430) There seems to be a lot of legacy bits scattered in the OSI software.

I've been working on getting hard disk emulation working on my OSI emulator. I have dumped the HD boot track for OS65U but unfortunately the emulator isn't up to booting it correctly. I need to run some of the boot code on the real thing to check timing values. It appears that 65U is much more sensitive to clock speed, and self-adjusts by counting the time it takes to write bytes out of the disk ACIA. I'm really looking for info on the 65U floppy format & OS. 65U seems more advanced than 65D.

__tarpitcod
Posts: 1
Joined: Mon Dec 05, 2011 1:52 am

OS65D blues

Post by __tarpitcod » Mon Dec 05, 2011 2:30 am

Hi All! It was great to find this forum, I grew up on a challenger 1P which had lots of things added to it by my dad (and me eagerly holding things as he soldered things to the board)...

All the OSI DOS's (for mini-floppys I can attest) were timing sensitive to the speed of the stepper motor in the minifloppy. I remember that we had to use an especially patched copy of OS65D / picodos that had slower stepper motor timings for the two drives my dad hooked up to the 610. (He had to build a data seperator too from memory).

Good luck with the dissasembly efforts -- I remember disassembling the monitor rom and thinking 'hey this part looks just like that part'.

Good luck on the hard drive disassembly too -- I remember drooling as a kid over those humungous 74MB drives...

I've got about 3 superboard II's, a C4P, a C4PMF, a C8P and the original C1PMF and a huge pile of Peek 65's / Aadvarks / software floppies and tapes back at my mums place in NZ. Alas - no OSI hardware here in the states where I am now. If I was back there I would dig them out and try out some answers to some of the questions.

--Tarp

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