Hard disk driver update plan

News,announcements,programming,fixes,game patches & discussions.

Moderator: Petari

Petari
Posts: 374
Joined: Tue Nov 28, 2017 1:32 pm

Re: Hard disk driver update plan

Post by Petari » Wed Apr 18, 2018 3:56 pm

Updates which allow 1GB partitions and lower RAM usage are in biggest part in TOS, and only smaller part in hard disk driver. Actually, it works fine with my very old DOS partition compatible driver, what needs program BigDOS, just now without it, what means faster work, less RAM usage and better compatibility.
Now, I really needed to test this TOS mod very thoroughly - there are over 250 changes in code. So, I did it last 3 months. It seems that yesterday I found last problem - what appeared in special cased of floppy change. That took 2 days with tracing.
Since I made code of it 4KB shorter - without removing anything, contrary, I added support for widely used DOS FAT16 Big partitions. Done just by using short addressing for for plenty of variable access in TOS code. It's especially good for 1.04, where is only 1KB free space normally, not it is 5KB.
And I working now on putting there my old idea: virtual floppy.
That may be very useful now, when work with floppy disks and drives is more and more problematic.
So, there will be special way of working with standard FAT12 floppy images, when they will act like floppy A and B . May change active image(s) during work by keypress. Up to 18 images of max 4MB size can be selected to be accessible as A and B. With FAT16 even larger capacity - what makes possible to put something on 8-10 floppies in single image file.
That will not replace completely real floppy drives and HW floppy emulators. Copy protected stuff, and SW accessing floppy controller directly, so not via TOS functions like Trap #1, RWABS and XBIOS 8, 9 will not work. What means mostly games. But best games are already made to work from hard disks, in much more comfortable way. Virtual floppy is intended to have access to floppy images without floppy drive, like images of user's disks. And as said, can do some things what can not with real floppies. Access to hard disk partitions may be disabled while in virtual floppy mode. Then no any extra RAM usage - same as when using real floppy drive. All code is in ROM.
There is 2 kind of people: one thinking about moving to Mars after here becomes too bad, the others thinking about how to keep this planet habitable.

Bikerbob
Posts: 62
Joined: Fri Nov 10, 2017 7:30 pm

Re: Hard disk driver update plan

Post by Bikerbob » Wed Apr 18, 2018 6:46 pm

All sounds very exciting, looking forward to giving it a try.

James

Post Reply