Signetics 2650 & 2636 programming/Tutorial code - getting started
Tutorial code - Getting started edit
This is the code for the tutorial Getting started
This code block must be merged with the standard 'Hardware definitions' code before it can be assembled |
reset_vector:
bcta,un reset
interrupt_vector:
retc,un ;just in case an interrupt occurs before we disable them
reset:
lodi,r0 $20 ;initialise program status word, just to be sure!
lpsu ;inhibit interrupts, stack pointer=0
lpsl ;register bank 0, without carry, arithmetic compare
eorz r0
stra,r0 effects ;initialise the 74LS378
bsta,un InitPVI ;initialise video chip
endless:
bctr,un endless
;===================================================================
; subroutine - initialise PVI
InitPVI:
eorz r0 ;r0 = 0
lodi,r3 $CA ;set 1F00-1FC9 to 00 (most of PVI)
loop1: ;sets all colours to black, turns off sound, score 1 field at top.
stra,r0 shape1,r3-
brnr,r3 loop1
lodi,r3 $0E
loopIS: ;load sprite shape and coords
loda,r0 one,r3-
stra,r0 shape1,r3
brnr,r3 loopIS
lodi,r0 $17
stra,r0 colours12
retc,un
one:
db $FF
db $81
db $81
db $81
db $81
db $81
db $81
db $81
db $81
db $FF
db 100 ;hc
db 100 ;hcb
db 100 ;vc
db 200 ;voff