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Signetics 2650 & 2636 programming/Tutorial code - sync to object completion

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< Signetics 2650 & 2636 programming
The latest reviewed version was checked on 24 December 2021. There are template/file changes awaiting review.

Tutorial code - Sync to object completion

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This is the code for the tutorial Sync to Object completion 

; Tutorial - Sync to object completion
;=============================================================================
        org     0
reset_vector:                   ; the microprocessor starts here when the reset button is pressed
        bcta,un reset
        org     3
interrupt_vector:               ; interrupts shouldn't happen, but set this just in case
        retc,un
reset:  
        lodi,r0 $20	        ; initialise program status word
        lpsu                    ; inhibit interrupts, stack pointer=0
        lpsl                    ; register bank 0, without carry, arithmetic compare

        eorz    r0
        stra,r0 effects         ; initialise the 74LS378

        bsta,un DefineUnused    ; push all unused objects offscreen
        lodi,r0 $AA             ; blank the score digits
        stra,r0 score12
        stra,r0 score34
        lodi,r0 %00000000       ;  X / 000              /   0     / 000
        stra,r0 backgnd         ;    / black background / disabled / black screen

        bsta,un Vsync0          ; make sure VRST hasn't started
endless:
        bsta,un Vsync1          ; wait for VRST to start

        bsta,un Object1A	; set initial state of object 1:
                                ; shape, colour, size, HC,VC
                                ; and HCB,VCB for first duplicate, B

        bsta,un Vsync0          ; wait for VRST to end 

        lodi,r1 $08
        bsta,un WaitObj         ; wait for object 1 to complete 

        bsta,un Object1B	; set first duplicate of object 1:
                                ; shape, colour, size
				                ; and VCB for second duplicate, C

        lodi,r1 $08
        bsta,un WaitObj         ; wait for object 1 to complete (first duplicate, B) 

        bsta,un Object1C	; set second duplicate of object 1:
                                ; shape, colour, size, HCB
				                ; and VCB to push next duplicate offscreen


        bctr,un endless

;==================================================================
; subroutine  -  Primary object 
; set initial state of object 1: shape, colour, size, HC,VC
; and HCB,VCB for first duplicate, B

Object1A:
        lodi,r3 10
        lodi,r0 $FF
loop1A:
        stra,r0 shape1,r3-         ; rectangle shape
        brnr,r3 loop1A

        stra,r3 objectsize      ;  size 0

        lodi,r0 $07             ;  white
        stra,r0 colours12

        lodi,r0 10
        stra,r0 vc1             ; vc = 10
	rrl,r0
        stra,r0 vcb1            ; vcb = 20
	rrl,r0  
        stra,r0 hc1             ; hc = 40
	rrl,r0
        stra,r0 hcb1            ; vcb = 80
     
        retc,un
;==================================================================
; subroutine  -  First duplicate 
; set: shape, colour, size
; and VCB for second duplicate

Object1B:
        lodi,r3 10
        lodi,r0 $FF
	ppsl    withcarry       ; include carry in rotate instructions
loop1B:
        stra,r0 shape1,r3-      ; triangle shape
        cpsl    carrybit
	rrr,r0                      ; shift right with 0 from the carry bit
        brnr,r3 loop1B

        lodi,r3 1
        stra,r3 objectsize      ;  size 1

        lodi,r0 $08             ;  yellow
        stra,r0 colours12

        lodi,r0 80
        stra,r0 vcb1            ; vcb = 80

     
        retc,un
;==================================================================
; subroutine  -  Second duplicate 
; set: shape, colour, size, HCB
; and VCB to push next duplicate off screen

Object1C:
        lodi,r3 10
        lodi,r0 $FF
	ppsl    withcarry       ; include carry in rotate instructions
loop1C:
        stra,r0 shape1,r3-      ; triangle shape
        cpsl    carrybit
	rrl,r0                      ; shift left with 0 from the carry bit
        brnr,r3 loop1C

        lodi,r3 2
        stra,r3 objectsize      ;  size 2

        lodi,r0 $28             ;  green
        stra,r0 colours12

        lodi,r0 250
        stra,r0 vcb1            ; make sure there are no more duplicates
        lodi,r0 60
        stra,r0 hcb1            ; hcb = 60
    
        retc,un

;===================================================================
; subroutine  -  define position of unused objects
             
DefineUnused:
        lodi,r0 254
        stra,r0 vc2      ; push unused objects offscreen
        stra,r0 vc3
        stra,r0 vc4

        lodi,r0 $FF            ; set all objects black
        stra,r0 colours12       
        stra,r0 colours34            
        retc,un

;=================================================================
; subroutine - wait for vertical reset to clear
                        ; (see Tutorial......)
Vsync0:
        tpsu    sense
        bctr,eq Vsync0          ; wait for Sense bit to clear
        retc,un
;=================================================================
; subroutine - wait for vertical reset to set
Vsync1:         
        tpsu    sense           ; wait for Sense bit to be set
        bctr,lt Vsync1
        retc,un
;=================================================================
;subroutine - wait for object to finish
                        
;  enter with r1=mask for bit to be tested:
;       obj1=$08, obj2=$04, obj3=$02, obj4=$01
WaitObj:
        loda,r0 objectstatus
        andz    r1
        bctr,eq waitobj
        retc,un
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