Atari 800 User Manual

118 User 's Handbook to the Atari 400/ 800 Computers
line 10. The current value of the counter is 6, and if the counter
was to be decr e mented again ,the counter would be4. However,
4 is less than the final value which is specified in the FOR
statement (the argument of TO). As a result, the l oop does not
continue after K =6 because another decrement would make the
counter l ess than the final value (5) .
If the counter of a loop is being inc remented, the lo op will be
executed
until the cou nt er would exceed the final value if it
were incremented again. For exa mple : FOR J = 1 TO 4 STEP 2
would be executed with J equal to 1 and 3. The counter (J) would
exceed the final value (4) if it were incremented again.
A
FOR / NEXT l oop should be executed as if it were a single
statement. An attempt to branch into a FOR/ NEXT loop will
cause an error.
EXAMPLE
10 GOTO 30
20 FOR I = 1 TO 10
30 PRINT I
40 NEXT I
RUN
ERROR- 13 AT LINE 40
In general, branching out of a FOR / NEXT loop will not cause an
error. However, exiting a lo op before it has comp leted should be
avoided.
FRE
The FRE function returns the number of bytes of memory
available. The FRE function requires an argument, but that
argument has no effect on the value returned.
CONFIGURATION
X = FRE (a)
EXAMPLE
PRINT FRE(O)

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