Atari 400 User Manual

208 User's Handbook to the Atari 400/800 Computers
Floppy diskettes come in two sizes: 8 inch and 5114 inch. The 5114
inch diskettes are also known as mini-floppy diskettes. The Atari
810 Disk Driv e uses mini-floppy diskettes.
Tracks & Sectors
To facilitate the proc ess of searching for data on the diskette
surface, that surface is divided into tracks and sectors.
Tracks may be visualized
as a series of concentric circles on the
diskette surface, as shown in illustration 7-3. Atari's DOS divides
a
diskette into 40 tracks.
To
further reduce the time necessary to search for a particular
data item, Atari's DOS divides each track into 18 sectors, which
are also shown in illu st ration 7-3.
With 40 tracks available and 18 sectors per track, Atari DOS
divides each diskette into 720 sectors. However , 18 of these 720
sectors are used by Atari DOS , and cannot be used to store
programs
or data.
One
Sector of
Track
Illustration 7-3. Tracks and Sectors
~--' ......
.," ----' .....
" ..... ,'
// .... --- ..... ,
//,. ...... "' \
1/ // ,---... "
/
'
I /' " '
1/1 \\\\
"/' 0 \\\
"~: 'II'
'\' }'I'
\ \ I'll
\\ \' B / '/1
\ \ ,,'... ...../ // / /
,
'- ...... ./ / /
'" ...... - _ ..... .//
,,, ,..
...... '----,.../
....... --.-~
Track

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)