mt87692@lehtori.tut.fi (Mikko Tsokkinen) (02/28/91)
Hello, I was programming yesterday evening and noticed a bug in hardware reference manual. About page 29 in copper section there is a example program making interrups every 16 scan lines, however it does not work. code is something like this dc.w $0f01,$8f00 ; wait for low 4 bits to become true signal processor (dont remember the opcode) dc.w $00e3,$00fe ; wait for line to finish ^^ Now this is wrong, it should be e1. Actually this is proposed to wait for scan line to end but actually it waits for position $8100 . The copper never reaches $e2 in horizontal direction (at least not in my amiga :-) when running in lores noninterlaced pal mode. This information can be by the way read from the blitter section DMA timing diagram. ... rest of the code removed ... Now you don't have to waste your time with this nonworking example (very typical in computer manuals in general:-) BTW my setup is 1MEG pal agnus, 1M CHIP, 8M FAST etc. MIT -- Bubble Bobble
ken@cbmvax.commodore.com (Ken Farinsky - CATS) (03/02/91)
In article <MT87692.91Feb27214136@lehtori.tut.fi> mt87692@lehtori.tut.fi (Mikko Tsokkinen) writes: > I was programming yesterday evening and noticed a bug in hardware reference >manual. About page 29 in copper section there is a example program making >interrups every 16 scan lines, however it does not work. > >code is something like this > >dc.w $0f01,$8f00 ; wait for low 4 bits to become true >signal processor (dont remember the opcode) >dc.w $00e3,$00fe ; wait for line to finish > ^^ Now this is wrong, it should be e1. Actually this is proposed > to wait for scan line to end but actually it waits for position > $8100 . The copper never reaches $e2 in horizontal direction > (at least not in my amiga :-) when running in lores noninterlaced > pal mode. This information can be by the way read from the blitter > section DMA timing diagram. >... rest of the code removed ... Well, you're half right and we're half right. As far as I know, this code was tested and works on an NTSC Amiga. However, talking with the author, your answer sounds right for a PAL machine. We'll look into this for the next rev of the hardware manual. -- -- Ken Farinsky - CATS - (215) 431-9421 - Commodore Business Machines uucp: ken@cbmvax.commodore.com or ...{uunet,rutgers}!cbmvax!ken bix: kfarinsky