TOS patch for more compatible, more efficient hard disk work

[ParanoidLittleMan]

Here are some important details: http://atari.8bitchip.info/tos105.html

I think that I did now, so many years later what Atari should do then - at least at 1989, when TOS 1.04 was launched. Real FAT16 filesystem, without those large logical sectors.

That some people at Atari were aware that it should be done little different proves this quote from file FS.H , from 1986 :

"
/*
** Type declarations
*/

#define BCB struct _bcb
#define FTAB struct _ftab
#define PD struct _pd
#define OFD struct _ofd
#define FCB struct _fcb
#define DND struct _dnd
#define DMD struct _dmd
#define CLNO int /* cluster number M01.01.03 */
#define RECNO int /* record number M01.01.03 */
/*** this should be changed to a long!! ***/
#define FH unsigned int /* file handle M01.01.04 */"

"

Indeed, record number needs to be long, for efficient work. And above is probably for TOS 1.02 - 256MB limit is because record number is signed. Cluster number should be unsigned too, for real FAT16 - then can have larger partitions.

 

This was over 2 weeks full time work, over 200 changes in code - without sources, done so that original RAM layout and variable addresses of TOS 1.04 are unchanged.

Edited February 1, 2018 by ParanoidLittleMan

[English Invader]

I don't understand the technical stuff but anything that improves TOS and hard drive support for non-STe users can only be a good thing. Awesome work as always.

[walter_J64bit]

Awesome work! Is there going to be a soft reset added? I'm using a STE TOS 1.62 US.

[ParanoidLittleMan]

I plan to do same with TOS 1.62 - it is very similar with 1.04. I'm sure that FAT filesystem is 100% same. Hard part will be disassembling it properly, then just need to perform same changes. And there is one good thing with 1.62 - plenty of free space at ROM end