Reading ED DOS 2.5 Directory in Assembly using DSKINV or SIOV

[eea]

I'm hoping that somebody can help with an issue I'm having reading an Enhanced Density (ED) Directory from a DOS2.5 disk using DSKINV.  In extensive Google searches, I found that when DOS 2.5 was introduced with ED support, it added a new parameter for CIO opening of the disk directory (In BASIC, OPEN #1,7,0,"D:" (rather than the SD OPEN #1,6,0,"D:")).  I haven't had any luck in finding a way to tell DSKINV to access the files beyond the normal 720 sectors.  My code to read the disk directory in assembly follows this code and pseudo code:

 

LDA # <360
STA DAUX1     ; Disk Directory Sectors are 360-367
LDA # >360

STA DAUX2

LDA #$52     ; "R"

STA DCOMND

LDX # >BUFFER

STX DBUFHI  
LDY # <BUFFER 

STY DBUFLO

JSR DSKINV

 

Then the code looks at each of the 16 bytes that are returned (if there are more valid entries) to build a directory structure

It loads up to 8 entries per sector for each of the 8 directory sectors and then repeats.

 

Anyway, this works fine for normal SD DOS 2.0 disks, but for DOS 2.5 using ED, the code only returns the files that are located within the first 720 sectors available to SD.

 

So, can somebody please let me know if it is possible to use DSKINV or SIOV to read the additional files in a DOS 2.5 ED disk (the ones that are marked with less than and greater than signs within DOS 2.5 itself)?  If it is possible, how do you tell DSKINV or SIOV to use the extended sectors for the directory sectors, or is it a flag somewhere in the 16 bytes of each directory entry?

 

Thanks so much!

Eric 

 

[phaeron]

Check the code you are using to detect valid files in the directory. DOS 2.5 files in the ED area use a flag configuration that is intentionally invisible to DOS 2.0 -- $03 instead of $42. If your code is testing bit 6 for a valid entry then it is probably dropping the additional files.

 

[eea]

Thanks so much, @phaeron!  That indeed was the problem - I was filtering out what is a valid file in the ED area but an invalid file in SD.

 

Thanks so much for all you do for the Atari community!