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This is a more readable than the other version. For this
reason, the macros will be used in the discussions of BIOS
routines and sample programs. To use BIOS functions in
your C programs, you must #include OSBIND.H if you use
the macros, and you must link your program with the library
that contains the b ios() function.
Character Device I/O
This group of functions enables communication with certain
I/O devices at the character level. These character devices are
sequential in nature, which means they transfer information
as a stream of characters sent one after the other, and the
receiver has no control over the order in which the informa
tion is sent. Devices such as the printer, the serial port, and
the keyboard differ in this regard from storage devices like
disk drives, which allow random access to information stored
at a particular location within named files. The BIOS I/O
functions only allow you to send or receive a single character
at a time. There are, however, XBIOS functions that allow
you to send a string of characters to the MIDI or Intelligent
Keyboard device with a single call.
The five character devices on the ST are shown in Table
2
1
-
.
The first three of these devices can be found on most
computers, while the last two are specific to the ST. Three of
the character devices can both send and receive information,
but the printer and intelligent keyboard devices can only re
ceive output (at least through the BIOS routines).
Do not confuse the intelligent keyboard device with the
console device. The console device consists of two physically
separate devices: the display screen and the keyboard. This
device receives ASCII characters from the keyboard and dis-
Table 2-1. The Five Character Devices
Device
Device
Name
Number
0
PRN:
AUX:
1
2
CON:
3
4
BIOS
Description
Parallel (Centronics) printer (output only)
RS-232 serial device (modem)
The console device (keyboard and screen)
MIDI (Musical Instrument Digital Interface)
IKBD, the intelligent keyboard device (output
only)
13
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