Commodore 128 Programmer's Reference Manual page 399

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INPUT/OUTPUT GUIDE 389
and involve no tuners. The C128 includes a port to accept the traditional monitors as
well as Commodore's 40-column 1702 color monitor. The C128 80-column color
capability is enhanced with the new 40/80-column color monitor Model 1902. In
this RGBI monitor, signals separately control each of the three color guns (red, green,
blue) for maximum clarity and detail.
The screen can be accessed as an input or output device through the OPEN
command as device 3.
OPEN 1,3
The screen is the default output device on the C128. Typing on the keyboard (device 0)
results in a screen character display output whenever the monitor is powered up. No
special commands are normally required. However, once control is sent to another
device, reversion to the screen may be desired.
Control of the screen display is available primarily with the PRINT command;
associated punctuation including the quote and the semicolon and common, BASIC
functions including the TAB(X), SPC(X), and CHR$(X) as well as the POKE com
mand. In addition, there are color controls, sprite animation and graphics keys.
If using the dual 1902 monitor or two separate 40- and 80-column monitors, it is
possible to swap control between the two screens via the 40/80 switch or pressing
the ESC and X keys. If one is used for text and the other for graphics, use the
GRAPHIC command.
The following command will also swap the display output device:
PRINT CHR$(27)"X"
In addition to a screen display, sound commands can be used through a Commodore
monitor or the television speakers. See Chapter 11, Sound and Music.
OUTPUT TO THE DATASSETTE
Commodore programs and files can also be stored on tape cassette using a special
recorder called the Datassette. Unlike most tape recorders, which store analog sinusoidal
signals, the Datassette stores digital pulse signals that are more distinct, resulting in
a reliable storage format. Compared to a disk storage system, tape is somewhat slower
and limited to program and sequential files. Access to the files on tape is sequential.
Just as DLOAD automatically loads a program from disk, LOAD loads a
program from tape. Similarly SAVE and VERIFY automatically default to tape. A
LOAD for machine code requiring a secondary address would be:
LOAD*'NAME", 1,1
I Access to tape for sequential files is made with an OPEN statement to device 1:
OPEN1,1
p A secondary address of 0 (default value) assumes the file is opened for reading
I (using INPUT# or GET#). A secondary address for writing (PRINT# statements)
requires a 1 or 2, where 2 includes an end-of-tape marker.
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