Commodore 2040 User Manual page 87

Chapter
9
RANDOM 1.00
PROGRAM LISTING
This chapter provides a complete listing of the random access program described in Chapter
6 under the heading of Random Access Example.
F.:EAD' T ' .
1 REM RANDOM 1.0
2 REM SUBROUTINES TO MANAGE RANDOM ACCESS FILES
3 REM VARIABLES ARE SET FROM DATA OF DESCRIPTOR FILE & KEY LIST FILES ...
4 REM ... DEFINED BY USER PROGRAM
5 REM VARIABLES SHOULD REFLECT DESIRED FILE STRUCTURE
6 REM ALL FUNCTIONS ACT UPON THE VARIABLES DEFINED BELOW
10 F.:EM
11 REM
* .
12 REM
13 POKEI022, 128:REM TURN DOS SUPPORT 3.1 OFF
15 M'=CHR$(13):REM FIELD MARKER
16 :;:;P'="
"+"":
REt'1 :;:;PACE FOR F'ADDING
20 C0=2: REM DIRECT CHANNEL
21 Cl=3: REM SEQUENTIAL CHANNEL
25 CC=15: REM COMMAND CHANNEL
30 D=0: REM CURRENT DRIVE
#
31 T=0: REM CURRENT TRACK
#
32 S=0: REM CURRENT SECTOR
#
35 DD=0: REM DESCRIPTOR DRIVE
#
36 F.:D=f1: REM F.:At·WOt1 DF.: I ' · . . . E
#
40 I D$=" " : REt'1
PAt~DOt1
DISK ID
45 NR=0: PEM
#
PECOPDS IN R-FILE
46 CR=0: REM CURRENT RECOPD
#
47 FR=0: REM 1ST FREE RECORD UNUSED
50 NF=0: REM
#
FIELDS IN RECORD
51 CF=0: REM CURPENT FIELD
#
55 PB=0: REM
#
PECOPDS PER BLOCK
56 RS=0: REM PECOPD SIZE IN BYTES
60 NB=0: REM
#
BLOCKS IN P-FILE
65 E=0: REM EPPOP FLAG, OK =0
66 REM EN$,EMS.ET$,ES$,ET,ES EPROR CHANNEL VAPIABLES
70 EP=.5/256: PEM INTEGEP
COPPECTI(~
75 AS=0: PEM INDEX ARPAY ADDRESSING STRATEGY
76 PEM AS=0: USE ARRAY INDEX; AS=I: T&S ARE SET, CR= RECORD OFFSET IN BLOCK
9f1 F.:EM "A" ' , "' A R I ABLES AF.:E TEt'1PORAR'T'
95 DN=8:0PENCC,DN,CC: REM DN= DEVICE NUMBEP
98 GOT02000: REM START OF USER PROGRAM
99 PEt1
89