| |
Conrad
Registered: Nov 2006
Posts: 840 |
Disk Drive Interrupts
Hello there.
May I ask if it's possible to get your own interrupt routines running on the disk drive using the VIA timer registers?
Since the drive also has an IRQ vector at $fffe/ffff, I've been trying to get my own IRQ routine to run using timer 1, but unfortunately no luck.
Here's the drive source of the IRQ routine I'm using:
DC_IRQ
pha
txa
pha
tya
pha
bit $180D ; interrupt from timer 1? (bit 6)
bvc DC_IRQ_ ; no, skip.
lda $1c00 ; Flash LED to make sure irq runs.
eor #$08
sta $1c00
DC_IRQ_
pla
tay
pla
tax
pla
rti
(This code is similar to the one stored in disk ROM)
I also have FFFF/FFFE vector set at this code location (DC_IRQ).
The problem is I'm not sure which VIA registers to set to enable timer 1 IRQ. I tried setting $180d, $180e and other IRQ related registers (also executing SEI before hand and CLI afterwards) but still nothing.
Could someone please help me which registers to set properly ?
I'm only doing this for tests BTW, just to see if it's possible to do. I'm testing it on 1541-I/II drives.
Cheers if you can help!
Owen. |
|
... 10 posts hidden. Click here to view all posts....
|
| |
Conrad
Registered: Nov 2006
Posts: 840 |
@Krill: Don't worry, I've only been doing these somehow useless routines just to (down to it all) learn how disk drives work.... after a couple days of stress it seems that you were right all along :D
Luckily I've purchased 1540/1541 and 1571 disk-drive in-depth technical service manuals, so I should be able to try out some better methods soon. |
| |
chancer
Registered: Apr 2003
Posts: 346 |
conrad I just was reading thru an old book.. noticed it mentioned a 1540, they recon it was made for the vic 20. the book say the screen must be turned off during the loading, by changing $d011.
with poke 53265,11
and when the things finished loading poke 53265,27
maybe thats of some use to you, maybe total rubbish, but I can't test that.
|
| |
Danzig
Registered: Jun 2002
Posts: 434 |
??? the Off-Topic-Detection-Bell is ringing...
conrad is testing around with DRIVE coding, not with switching the SCREEN on/off :D
|
| |
chancer
Registered: Apr 2003
Posts: 346 |
Quote: ??? the Off-Topic-Detection-Bell is ringing...
conrad is testing around with DRIVE coding, not with switching the SCREEN on/off :D
what is it with certain (not all) alphaflight members? hhmm u went x95, probably explains your attitude.
unless you have a vic 1540 drive,and know 100% about that, then how can you comment, go buy one prove me wrong ;-)
so yer i do think its relivant, or at least trying to be helpful even if its found to be in-correct (unlike your comment), since it's a drive actually designed for the vic 20, that maybe someone might use (chances are small, but who knows)
go and look in a book "com. 64 omnibus - a comprehensive programming handbook" by peter lupton / frazer robinson, page 400 of that.
|
| Previous - 1 | 2 - Next |
