Atari 800 User Manual

198 User's Handbook to the Atari 400/800 Computers
R ecorde r. This area of memory is known as the cassette buffer.
As mentioned ea rlier in thi s chapter, data is organized into fil es,
record s, and fields. The notion of file s, r eco rd s, and fields relate
to a programmer's concep tion of how a data fi le is organized.
In ac tualit y, a cassette data fi le ph ys i ca lly consists of three
separate parts: the leade r, data block s, a nd an e nd-of-file
re co rd.
The
20 second data file leader allows th e Atari computer and 410
Program Recorder to sy nc hroni ze their timing so that dat a may
be tr a nsferr ed. The ac tual data is stored in blo c ks of 128
characters eac h.
The
l as t blo ck (k no wn as the end-o f -f ile bl ock) can consist of
few er than 128 char ac ters of data. This bl ock hold s the final
characters of the data file (i.e. Those characters still remaining
after the last comp lete bl oc k has been utilized.).
Records can co ns ist of mor e than one block, l ess than one block,
or exactly one block. The co mput er wil l ass ign re co rds to data
blo cks automatica ll y. The programmer need not concern
him se lf with thi s pro cess.
Opening Data Files
Before information can be read from or written to a data file, that
file must first be opened. This is accomplished with the OPEN
statement.
The data
file can be r ea d from or wr itt en to as l ong as it is ope n.
To prevent access to the file, it must be closed. This is
accomplished with the CLOSE s tatement.
The OPEN statement uses the following configu r ation:
OPEN #channe/, task, value, device
OPEN can be used with external devices other than the 410
Pro gram Recorder including the disk, screen, keyboard, printer,

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS