Signetics 2650 & 2636 programming/Tutorial code

Tutorial code - Introduction


This section of the book contains all the code used in the tutorials.

The code below must be appended to every program before it can be assembled. It contains the equate direcitives that assign labels to all the hardware addresses and related constants. This is done both to avoid repetition and also to ensure consistent labelling of registers throughout this book.

Hardware definitions


This is a standard block of assembler directives that give names to constants and memory addresses of all the registers in the system. Notice that some addresses such as $1F00 have several labels. This allows the programmer to use the one most appropriate to the task being performed as an aid to making readable code. For example, if all the PVI registers are being initialised to 0, use pvi; if setting up object 1 shape and position use 'object1' etc.

;   updated 11 Jan 2021

; -------------------
carrybit        equ $01
compare         equ $02
withcarry       equ $08
registerselect  equ $10
intinhibit      equ $20
stackpointer    equ $07
sense           equ $80
flag            equ $40

; ----------------
effects         equ $1e80

; --------
player1keys147c equ $1E88 ;player1 keypad, bits: 1,4,7,clear,x,x,x,x
player1keys2580 equ $1E89 ;player1 keypad, bits: 2,5,8,0,x,x,x,x
player1keys369e equ $1E8A ;player1 keypad, bits: 3,6,9,enter,x,x,x,x
player2keys147c equ $1E8C ;player2 keypad, bits: 1,4,7,clear,x,x,x,x
player2keys2580 equ $1E8D ;player2 keypad, bits: 2,5,8,0,x,x,x,x
player2keys369e equ $1E8E ;player2 keypad, bits: 3,6,9,enter,x,x,x,x
keymask123      equ $80     ;top row of keys
keymask456      equ $40
keymask789      equ $20
keymaskc0e      equ $10     ;bottom row of keys
console         equ $1E8B ;start and select buttons on console
consolestart    equ $40
consoleselect   equ $80

; ---------------------------
pvi          equ $1F00

object1      equ $1F00
shape1       equ $1F00
hc1          equ $1F0A ; hc = Horizontal Coordinate
hcd1         equ $1F0B ; hcd = Horizontal Coordinate Duplicate
hcb1         equ $1F0B ; hcb =  ditto  (Signetics datasheet name)
vc1          equ $1F0C ; vc = Vertical Coordinate
voff1        equ $1F0D ; voff = Vertical Offset
vcb1         equ $1F0D ; vcb =  ditto  (Signetics datasheet name)

object2      equ $1F10
shape2       equ $1F10
hc2          equ $1F1A 
hcd2         equ $1F1B 
hcb2         equ $1FCB
vc2          equ $1F1C 
voff2        equ $1F1D 
vcb2         equ $1F1D

object3      equ $1F20
shape3       equ $1F20
hc3          equ $1F2A 
hcd3         equ $1F2B 
hcb3         equ $1F2B 
vc3          equ $1F2C 
voff3        equ $1F2D
vcb3         equ $1F2D

object4      equ $1F40
shape4       equ $1F40
hc4          equ $1F4A 
hcd4         equ $1F4B 
hcb4         equ $1F4B 
vc4          equ $1F4C 
voff4        equ $1F4D  
vcb4         equ $1F4D 

grid         equ $1F80     ; background grid
vbars        equ $1F80     ; vertical bar definitions
hbars        equ $1FA8     ; horizontal bar extensions

objectsize   equ $1FC0

colours12    equ $1FC1     ; colour objects 1,2
colours34    equ $1FC2     ; colour objects 3,4
coloursback  equ $1FC6     ; background grid colour / background grid enable / screen colour
backgnd      equ $1FC6     ;     deprecated

pitch        equ $1FC7

scoreformat  equ $1FC3
score12      equ $1FC8
score34      equ $1FC9

objectstatus equ $1FCA     ; object-background collision / object complete
obj1complete equ $08
obj2complete equ $04
obj3complete equ $02
obj4complete equ $01
collisions   equ $1FCB     ; VRLE / inter-object collision
vrle         equ $40
adpot1       equ $1FCC
adpot2       equ $1FCD