Apple Apple-1 - Page 7

6502
HEX
MONITOR
LISTING
FF00
D8
RESET
CLD
FF01
58
CLI
FF02
A0 7F LDY #$7F
FF04
8C
12 D0 STY DSP
FF07
A9
A7
LDA
#$A7
FF09
8D 11
D0 STA
KBD CR
FF0C
8D
13
D0
STA DSP
CR
FF0F
C9
DF
NOTCR
CMP
#$DF
FF11
F0
13 BEQ BACKSPACE
FF13
C9
9B CMP #$9B
FF15
F0
03
BEQ
ESCAPE
FF17
C8 INY
FF18
10
0F
BPL NEXTCHAR
FF1A
A9 DC
ESCAPE
LDA #$DC
FF1C
20
EF
FF JSR
ECHO
FF1F
A9 8D GETLINE LDA #$8D
FF21 20
EF
FF JSR
ECHO
FF24
A0
01
LDY
#$01
FF26
88
BACKSPACE
DEY
FF27 30
F6
BMI
GETLINE
FF29
AD 11 D0 NEXTCHAR LDA KBD
CR
FF2C
10
FB BPL NEXTCHAR
FF2E
AD
10
D0
LDA
KBD
FF31
99
00
02
STA
IN, Y
FF34 20
EF FF
JSR
ECHO
FF37 C9 8D CMP #$8D
FF39 D0
D4
BNE NOTCR
FF3B
A0
FF LDY #$FF
FF3D
A9
00
LDA
#$00
FF3F
AA
TAX
FF40
0A
SETSTOR ASL
FF41
85 2B SETMODE
STA
MODE
FF43
C8 BLSKIP INY
FF44
B9
00
02
NEXT ITEM LDA
IN,
Y
FF47
C9 8D CMP #$8D
FF49
F0 D4
BEQ GETLINE
FF4B
C9
AE
CMP
#$AE
FF4D
90
F4
BCC
BLSKIP
FF4F F0
F0
BEQ
SETMODE
FF51
C9
BA
CMP
#$BA
FF53
F0 EB BEQ SETSTOR
FF55
C9 D2 CMP
#$D2
FF57
F0 3B
BEQ RUN
FF59
86 28 STX L
FF5B
86
29
STX H
FF5D
84
2A
STY YSAV
FF5F
B9
00
02
NEXTHEX LDA IN,
Y
FF62
49
B0
EOR
#$B0
FF64
C9
0A
CMP
#$0A
FF66
90
06
BCC
DIG
FF68
69
88
ADC
#$88
FF6A
C9 FA CMP
#$FA
FF6C
90
11
BCC
NOTHEX
FF6E
0A
DIG
ASL
FF6F
0A
ASL
FF70
0A
ASL
FF71
0A
ASL
FF72
A2
04
LDX
#$04
FF74
0A
HEXSHIFT ASL
Clear decimal
arithmetic mode.
Mask for
DSP
data
direction
register.
Set
it
up.
KBD and
DSP
control
register
mask.
Enable interrupts,
setCAl,
CB1, for
positive
edge
sense/output mode.
Yes.
ESC?
Yes.
Advance
text
index.
Auto ESC if
>
127.
n
\
ti
Output
it.
CR.
Output it.
Initiallize
text
index.
Backup
text
index.
Beyond
start of
line, reinitialize.
Key
ready?
Loop
until ready.
Load character. B7 should be 'l
1
.
Add
to text
buffer.
Display
character.
CR?
No.
Reset text
index.
For XAM
mode.
0-*X.
Leaves
$7B
if setting STOR
mode.
$00
=
XAM,
$7B
=
STOR,
$AE
=
BLOK XAM
Advance
text
index.
Get
characte
r.
CR?
Yes,
done
this
line.
"
.
"
?
Skip
delimiter.
Set
BLOCK XAM
mode.
II.
M
9
Yes, set
STOR mode.
,f
R"?
Yes,
run user
program.
$00-*L.
and
H.
Save
Y
for comparison.
Get
character for hex
test.
Map digits
to
$0-9.
Digit?
Yes.
Map letter
"A
,,
-
n
F" to
$FA-FF.
Hex
letter?
No,
character not hex.
Hex
digit
to
MSD of
A.
Shift count.
Hex
digit left, MSB
to
carry,
-5-