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Forums > C64 Coding > CIA #1 Timer A settings
2017-08-13 09:24
TWW

Registered: Jul 2009
Posts: 434
CIA #1 Timer A settings

During IO Init, the CIA #1 Timer A is set as follows:

.C:fddd  AD A6 02    LDA $02A6
.C:fde0  F0 0A       BEQ $FDEC
.C:fde2  A9 25       LDA #$25
.C:fde4  8D 04 DC    STA $DC04
.C:fde7  A9 40       LDA #$40
.C:fde9  4C F3 FD    JMP $FDF3
.C:fdec  A9 95       LDA #$95
.C:fdee  8D 04 DC    STA $DC04
.C:fdf1  A9 42       LDA #$42
.C:fdf3  8D 05 DC    STA $DC05


Except for the Old NTSC which sets it directly (modified KERNAL):

.C:fddd  A9 1B       LDA #$1B
.C:fddf  8D 04 DC    STA $DC04
.C:fde2  A9 41       LDA #$41
.C:fde4  8D 05 DC    STA $DC05


Can someone confirm that the DREAN uses the same method as the top one (same as PAL and NTSC)?
2017-08-13 13:36
The_WOZ

Registered: May 2006
Posts: 25
On mine is the same as the top one.
2017-08-13 22:57
TWW

Registered: Jul 2009
Posts: 434
Thanks!
2017-08-14 05:18
The_WOZ

Registered: May 2006
Posts: 25
I'll ask around on the local argentine forum.
Drean mainboards came from all revisions, anything Commodore had lying around to be refurbished.
So it might not be too far fetched that there is some with an old NTSC Kernal around.
2017-08-19 18:26
The_WOZ

Registered: May 2006
Posts: 25
5 Dreans checked so far, all have the normal Kernal.
2017-08-19 21:41
TWW

Registered: Jul 2009
Posts: 434
Awesome.

As the KERNAL seem to count raster-lines (by using raster compare) to distinguish between NTSC/PAL, it should be safe to assume the DREAN uses the same setting as PAL.
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