are the device/io controlblocks reset to zero after the SIOV/CIOV?

[Marius]

Just wondering:

 

after a JSR SIOV are the Device Control Blocks like DBYTLO and DBYTHI reset to zero?

 

I mean:

 

Do I need to set them each time after a JSR SIOV?

 

Or better asked:

 

after a JSR SIOV do I need to do a LDA #$00, STA <whatever control thing> each time or can I assume that they are reset to zero after a JSR SIOV?

 

Thanks

M.

[phaeron]

They are largely preserved by SIOV, with the exception of DSTATS which is changed to the status code. The game Dimension X relies on the DCOMND byte at least not being modified. You would need to reset DSTATS for the next sector read, but if you're done reading from the disk I don't think you need to reset anything.

[Marius]

so when I write #$80 to dbytlo and #$00 to dbythi and (and the rest) and then I do JSR SIOV, I do not have to set dbytlo to #$80 again?

[+Larry]

Can you look at the blocks after use with Omnimon or BUG or another monitor? BTW, a very early command line dos for the Atari, K-Dos, had a built-in monitor (not that there aren't lots of alternatives these days).

 

-Larry

 

so when I write #$80 to dbytlo and #$00 to dbythi and (and the rest) and then I do JSR SIOV, I do not have to set dbytlo to #$80 again?

[Rybags]

The status byte should be the only one you need to set back to the needed value.

 

Of course you'd usually also change the buffer address and AUX values as well if doing r/w operations to a disk.