User`s manual

80 INPUT# 5, A$, X

90 IF A$ < > "Record Contents #" OR X < > R THEN STOP

110 PRINT# 15, "B-F:" 0, T, S "'"

120 NEXT R

Checks To Make

Sure Data Is OK

130 CLOSE4: CLOSE 5

140 PRINT# IS, "S0:KEYS"

150 CLOSE 15

BUFFER-POINTER

The buffer pointer keeps track of where the last piece of data waswritten.

It also is the pointer for where the next piece of data is to be read. By changing

the buffer pointer's location within the buffer, you can get random accessto the

individual bytes within a block. This way, you can subdivide each block into

records.

For example, let's take a hypothetical mailinglist. The information such as

name, address, etc., will take up a total of 64 characters maximum. We could

divide each block of the random access file into 4 separate records, and by

knowing the track, sector, and record numbers, we can access that individual

record.

FORMAT FOR BUFFER-POINTER COMMAND:

PRINT# file#, "BUFFER-POINTER:" channel, location

or abbreviated as

PRINT# file#, "B-P:" channel, location

EXAMPLE OF SETTING POINTER TO 64TH CHARACTER OF BUFFER:

PRINT# 15, "B-P:" 5, 64

Here are versions of the random access wwiting and reading programs

shown above, modified to work with records within blocks:

SAMPLE PROGRAM WRITING 10 RANDOM-ACCESSBLOCKS WITH 4

RECORDSEACH:

10OPEN

15,8,15

20 OPEN 5, 8, 5, "#

30 OPEN 4, 8,4, "KEYS,S,W"

40 A$= "Record Contents #"

50 FOR R=1TO 10

60 FORL=1 TO 4