Table 6-2.
PET
Memory Map
(Rev.
3 ROMs) (Continued)
Memory Address
Sample Value
Description
Decimal
Hexadecimal Decimal
Hexadecimal
RAM Subroutines
112-135
0070-0087
230
E6
Roullne
la
fetch
nexl
BASIC character
173 AD
118 76 Enlry
la
refelch current characler
1904
0770
119-12077-78
POlnler Inlo source
lext
136-140
0088-008C
128 80 Next random no ln storage and
RND
work
area
OS
Page Zero Storage
141-143
008D-008F
398710
061576
24-hour clock Incremented every
1/60
sec-
ond
IJllfy} Resets every 5.184.000 Jlffles
124
hoursl Slored ln hlgh ta
low
arder
144-145
0090-0091
58926
E62E
Hardware
interrupt vector
146-147
0092-0093
64791 FD17
6502
BRK
Inslruction
Interrupt
veclor
148-149
0094-0095
50057 C389
NMI Interrupt vector
150
0096
0 00
Status
word
ST
Il
bytel
151
0097
255
FF
Matrrx coordlnate of key depressed at cur-
rent
Ilffy
1-80~key.
255~no
key
152
0098
0
00
Status of SHIFT key:
O~unshlfled
lupl
1
~shlfted
Idownl
153-154
0099-009A
65282
FF02
Correction factor for clock
155
009B
255
FF
Keyswltch
PIA
STOP
and
RVS
flags
156
009C
0
00
Timing
constant buffer
157
009D
0 00
1/0 flag
O~LOAD
1
~VERIFY
158
009E
0 00
Number of characlers ln keyboard
buffer
10
ta
91
159
009F
0
00
Fla0 ta
mdicale
reverse field
on
(O~normall
160
OOAO
0
00
IEEE
488
output
flag
FF~character
waltlng
161
OOAl
13
OD
Byte pOinter
ta
end of Ilne for
Inpul
162
00A2
0 00
Utrllty
163-164
00A3-00M
11. 13 OB.OD
Cursor log (row.
columnl
165
00A5
63
3F
IEEE
488
output
character buffer
166
00A6
255
FF
Key
Image
167
00A7
1
01
Flag for cursor enable:
O~Enable
1
~Dlsable
168
00A8
17
11
Counter ta flrp cursor
120
ta
11
169
00A9
32
20
Copy of character at current cursor position
170
OOAA
0 00
Flag for cursor
on/off
O=cursor
moved
1
~bllnk
starled
171
OOAB
0 00
Flag for tape wrrte
172
OOAC
0 00
Flag for
1
nput
source·
O~keyboard
buffer
l
=screen
memory
336
To Next Page
Loading...
