OS/A+ 4.1 customization

[tschak909]

Has anyone attempted to customize an OS/A+ installation to add something other than a 180K or 360K disk? 

 

It's very much possible by modifying DRVTAB, and adjusting the DRVTAB. It is also indicated that INIT.COM needs to be modified (source code available from OSS), has anyone gotten that source code? or will I need to just disassemble it and see how/where the drive parameters are derived?

 

I want to try and make a 16MB disk.

 

-Thom

[tschak909]

I also find it very interesting that OS/A+ 4.1 needed a separate COPY24.COM command to move files from the Atari DOS FMS to the v4 FMS.

 

This is strange to me, because the ADOS.COM is LITERALLY a resident CIO driver that implements the A: device, which implements a full copy of the DOS 2.0 FMS.

 

What gives?

 

-Thom

[Kyle22]

If you found a good copy, please post it.

I WANT a FujiNet, BTW. Can't wait until it's perfected.

:)

 

[tschak909]

The version that is publically posted, is a good copy. If anything it's slightly out of spec because the first three sectors are 256 bytes.

 

I'll post a copy here that's on a 360K disk:

 

 

OSA_41.atr

[tschak909]

I _REALLY_ like OS/A+ 4.1, and would like to figure out how we can properly document configuring different drive types, as this is only partially documented in the manual.

 

Fun fact, there is no max directory entries limit.

 

-Thom

[tschak909]

 

Long filenames. The copy utility however, is ported as is from v2, and caps after 12 characters. whoops.

 

-Thom

[tschak909]

Ah, I also see why they did COPY24. The COPY command has some _REALLY_ stupid assumptions in it. A2:FOO.COM literally becomes D2:FOO.COM, which uses the wrong CIO driver. sigh.

 

They really rushed this thing out the door.

 

-Thom

[tschak909]

Actually nevermind, something else happening. I read the trace wrong.

 

-Thom

[tschak909]

#Atari8bit #FujiNet - The production code unifies all of the individual #Arduino tests under PLATFORM.IO. Disk, Printer, WiFi modem, with the N: device to be implemented next. See them all working, here:

 

[drac030]

Regarding the OS/A+ 4.1, I remember playing with it some time ago, and:

 

1) it would be better for it to keep MEMLO lower. IIRC, it was $2C00.

 

2) the filesystem used does not seem to allow detection of the EOF earlier than at a sector boundary. So, create a file, write 1 byte to it, close the file - and while reading it later you will get back your byte + 255 zeros before status 136 comes in.

 

Apple DOS FS (which is used there) does not hold the file's exact length anywhere, on Apple text files always end with an EOF character, and the rest keeps the actual file's length in the header of the file itself. So the directory keeps actual type of the file: 0 for a text file, 1 for Integer BASIC, 2 for Applesoft BASIC, 4 for binary file... Not very practical thing on Atari, I would say.

Edited February 29, 2020 by drac030
typo