Tandy 1000 Programmer's Reference Guide

Chuwter 1 I System Calls
SetRelRec
Set Relative Record
Function Call
24H
Sets the relative record field (offset 21H) in a specified FCB to
the same file address that is indicated by the current block (off-
set 0CH) and current record (offset 20H) fields.
Entry Conditions:
AH = 24H
DS:DX = pointer to an opened FCB
Macro Definition:
5et-relative-record macro fcb
mov dx,offsetfcb
mov
ah,24H
int 21 H
endm
Example:
The following program copies a file using the Random Block
Read and Random Block Write function calls. It speeds the copy
by setting the record length equal
to the file size and the record
count to
1, and using a buffer of 32K bytes. It positions the file
pointer by setting the current record field (offset 20H)
to 1 and
using the Set Relative Record function call
to make the relative
record field (offset 21H) point to the same record as the combina-
tion
of the current block (offset 0CH) and current record (offset
20H) fields.
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Tandy 1000 Specifications

General

Processor	Intel 8088
Processor Speed	4.77 MHz
RAM	128 KB (expandable to 640 KB)
Operating System	MS-DOS 2.11
Manufacturer	Tandy Corporation
Release Year	1984
Storage	Single or double 5.25" floppy disk drive (360 KB), optional hard drive
Sound	Tandy 3-voice sound
Ports	Parallel, Serial
Graphics	CGA (Color Graphics Adapter)
Graphics Modes	320x200, 640x200