Imsai 8080 - Page 49

GAME PROGRAM LISTING (CONT.)
General Assembly and
Test Instructions
OCTAL HEX
ADD. INST.
ADD.
INST.
MNEMONIC DESCRIPTION
036 303
IE
C3
JMP
jum p
037 006
IF
06
(to read loop)
040 000
20
00
CHAN GE DIS P L A Y IF SWITCH D IF F E R E N T
041 250 21 A8 XR A, B
Exclusive OR B with A
042
107 22 47 MOV B, A
Store A in B
043
323 23 D3 OUT
Output A
044 377
24
FF
in front panel lights
045 257 25
AF
XRA, A
Exclusive OR a with itself A (put zero in A)
046 147 26 67 MOV H, A
Move A to H (set counter to insure enough delay fo r debounce)
047 057
27 2F CMA
Complement A (to all I’s)
050
117 28
4F MOV C, A
Move A to C (set C to debounce)
051
303 29 C3 JMP
Jump
052 006 2A 06
(to read loop)
053
000 2B 00
NOTE:
Exclusive OR of two switch patterns results in I’s in
positions which were changed.with all 0’s elsewhere.
8= D ISPLA Y BYTE STORAGE
C=SWITCH DEBOUNCE IN DIC AT O R
l=D EBO U NCE 0 = N O RM A L O PERA TION
D= LAST SWITCH SE TTINGS
E=CURREN T SWITCH S ETTINGS
H ,L=D £ L A Y C O U NTE R
SP =IN CRE M ENT FOR DELA Y CO U N TER
49
c)1975 IMS Assoc Inc