A86: im 2
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A86: im 2
I would like to thank Jimmy Merdell for his information about interupts.
Also when looking back at the source for "graylib.h" a commonly used
grayscale routine for the ti-85, i noticed this peace of code I couldn't
find the use for. It sets $100 bytes to NOP ($88), and then install the
interupt after that. Is this here because the databus returns random
information, and therefore the interupt vector will have the last byte
random, and generaly speaking thats not good (there is a better way to
say that I'm just not sure how)
InstallInterrupt
ld a,$088
ld hl,$8700
ld (hl),a
inc hl
ld b,0
CopyLoop
ld (hl),a
inc hl
djnz CopyLoop
; code goes on to actually install the interupt
Also, what is the difference between RET($C9), RETI ($ED$4D), and RETN
($ED$45)? I'm confused I just thought that, ret was roughly equivalent
to : POP PC. And what exactly is the databus, is it a pin on the pinout
of the Z80. Also this is stupid but, when the z80 gets power, i.e.
boots where does the PC point (I mean when batteries are first put it
not when the ON button is pressed, because doesn't the calc just
susppened itself and wait for the ON interupt when you turn it off?)?
Thank you for all your help, even though I may sould like an idiot.
-Gen_Witt
Gen_Witt@aloradus.com