How to implent PBI routines back in an OS

[Marius]

Hi.

 

As some know I am 'tweaking' MyIDE OS 3.1 ... although this versions lacks a lot of nice features the new Firmwares have, I think MyIDE OS 3.1 was the release that came as close as possible to a standard ATARI XL/XE OS. It is an extremely compatible OS, and I like it.

 

I'm in the final stage of fixing existing bugs, and I think it is really a nice 'plan B' myIDE OS to use.

 

But now the question:

 

Mr. Atari (the original author of this OS) left out (or at least: disabled) the PBI routines. I want to re-enable them, but I don't know how.

 

When I compare the MyIDE OS 3.1 with the original Atari Xl/XE OS I conclude that PBI routines are still there, so my guess is that they are just disabled.

 

Anyone a clue which steps to make to get PBI working again?

[Rybags]

Look for references to $247, $248 and $D1FF in the original and see if they exist in the modified OS.

 

Boot a disk image in Altirra and trap read to $E459 in each OS. Then trace through and see if they do the same thing.

You'd not need to trace the entire IO operation, the PBI check happens fairly early in a SIO call.

 

You can also set up an emulated IDE Plus 2 in Altirra which is a PBI compliant device.

 

My guess is the easiest way to disable PBI is probably somewhere in the OS Cold/Warmstart code.

There's also PBI relevant code in the resident IRQ handler, so maybe check for differences there too.

[Shawn Jefferson]

I think you'll find that Mr.Atari overwrote large portions of the PBI routines...

[Marius]

@shawn

 

No he did not in MyIDE 3.1

 

I'm 100% sure about that. I remember the time I was trying to let MyIDE 3.1 work together with the Mux. He send me (back then) MyIDE 3.1 OS back with the PBI routines back installed. Unfortunately I can not find that ROM anywhere anymore.

 

I wished I had dropbox years ago. Now I never lose anything...

[flashjazzcat]

Sijmen told me the other day that the latest MyIDE OS versions have the PBI routines fully reinstated. I'd found PENTV (IIRC) to be missing in earlier versions, which broke a lot of software.

[phaeron]

PENTV looks intact in 3.1. The PBI initialization scan is also still there, which really should have been disabled for the internal version as it writes commands to the IDE device. The critical part missing for PBI block devices, though, is the hook at the beginning of the SIO routine to poll the PBI ROMs to see if any one them want to handle the request.

[Shawn Jefferson]

It's been a long time since I've looked at 3.1... but that's the version I originally disassembled to write my own utilities for. Looking into the source of those old versions, there are MyIDE routines at C812 and C85C... overwriting something in the XL OS there.

[sup8pdct]

You will need to check the sio routine to see if pbi devices are looked for.

Also check IRQ service routine to see if $D1FF is also looked at etc.

 

James

[Marius]

Thank you all for your detailed responses! This is really helpful people!

 

I haven't had time yet to look at this further (There was suddenly a game called MULE brought under my attention hehe).

 

But I wanted to let you all know that I appreciate all your help. When I have succeeded a bit more on this, I'll let you all know!