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Forums > C64 Coding > Loading and saving to disk using kernel
2018-06-13 18:59
JackAsser

Registered: Jun 2002
Posts: 1987
Loading and saving to disk using kernel

Assume: Machine booted from cart. Cart ROM at $8000-$bfff. IO at $Dxxx and KERNAL at $e000-$ffff

What calls do I have to do to use KERNEL load/save?
What RAM and ZP will be trashed by this?
How will it affect my IRQs? (I have CIA1 and raster IRQs running via $0314/15)
 
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2018-06-15 18:26
ChristopherJam

Registered: Aug 2004
Posts: 1370
Quoting Oswald
kernAl

And Betty when you call me you can calllll, meeeee, Al :)
2018-06-19 11:54
Martin Piper

Registered: Nov 2007
Posts: 631
Code used for Berzerk Redux. I used the disk drive for hiscore storage with an optional custom load/save: https://github.com/martinpiper/C64Public/blob/master/BerzerkRed..

Citadel2 cartridge code, works with kernal replacement and CBM80 boot carts (EF and GMod2). Also tests cart banking: https://github.com/martinpiper/C64Public/blob/master/Citadel2/C..
2018-06-19 11:55
JackAsser

Registered: Jun 2002
Posts: 1987
Quote: Code used for Berzerk Redux. I used the disk drive for hiscore storage with an optional custom load/save: https://github.com/martinpiper/C64Public/blob/master/BerzerkRed..

Citadel2 cartridge code, works with kernal replacement and CBM80 boot carts (EF and GMod2). Also tests cart banking: https://github.com/martinpiper/C64Public/blob/master/Citadel2/C..


Awesome Martin! Thanks!
2020-04-05 18:31
Rastah Bar

Registered: Oct 2012
Posts: 336
I saved a file with this routine from codebase:
https://codebase64.org/doku.php?id=base:saving_a_file
That works fine.

But when I want to load it again via
https://codebase64.org/doku.php?id=base:loading_a_file
it never returns from JSR $FFD5. It gets stuck in some loop at $EE30.

I'm not using any ZP adresses above $8f. But I did disable timer interrupts earlier:
lda #$7f
sta $dc0d    
sta $dd0d
lda $dc0d
lda $dd0d

Enabling them before calling the load routine doesn't seem to help. I also disabled raster IRQs before calling the routine:
sei
lda #0
sta $d01a
inc $d019
lda #$37
sta $01   ;I used $fffe and $ffff, so this should be fine

The call to the load routine is done from main.
Does anybody have an idea why the load routine doesn't return and/or suggestions what I could try?
2020-04-05 18:36
chatGPZ

Registered: Dec 2001
Posts: 11101
i'd try calling the IORESET (or whatever its called) kernal call before, if that does the trick strip it down :)
2020-04-05 19:10
Rastah Bar

Registered: Oct 2012
Posts: 336
Thanks, but calling $FDA3 (IOINIT) doesn't help.
2020-04-06 09:38
oziphantom

Registered: Oct 2014
Posts: 478
have you made an intentional or unintentional modifications to dd02/3
2020-04-06 09:57
Rastah Bar

Registered: Oct 2012
Posts: 336
Intentional no, unintentional unlikely.
2020-04-06 10:41
tlr

Registered: Sep 2003
Posts: 1703
dd02 and dd03 was my thought also initially but $fda3 resets those.

Perhaps you have fiddled with the IEC bits in $dd00 and left the bus in a bad state? The drive could be hanging waiting for something to complete perhaps?
2020-04-06 10:50
Rastah Bar

Registered: Oct 2012
Posts: 336
It looks a bit as if something went wrong while saving the file, althoug no error was returned. When I try to load the file directly from Basic after a cold start with load "*",8 or load "*",8,1 the same problem happens.
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