Atari ST series Technical Reference Manual page 55

XBIOS Device and System Functions
Table 3-7. Structure of Table Pointed to by prtable (continued)
Byte Element
Number Name
type
22-23
24-25 port
26-29 masks
The prtblk() routine uses a number of RAM vectors. Be­
fore it sends a character to the printer, it jumps through a
vector to a subroutine that returns the status of the printer.
A return of — 1 means the printer is ready, while a return of
0 means that it's still busy. When the printer is ready,
prtblk() pushes the character to be printed onto the stack
and jumps through another vector to the subroutine that ac­
tually outputs the character to the printer. The four RAM
vectors, two for serial printers and two for parallel printers,
are:
Table 3-8. RAM Vectors for Printers
Vector
Address
Name
1286 ($506) prv__lsto
1290 ($50a) prv__1st
1294 ($50e) prv__auxo
1298 (512) prv__aux
These vectors can be used to divert screen prints to
other devices such as a laser printer connected to the DMA
port. Note, however, that since prtblk() only supports the
default printers, changing these vectors will not have any ef­
fect if a custom driver is installed at the vector at $502.
Description
Printer type
0 = Atari monochrome dot-matrix
1 = Atari monochrome daisywheel
2 = Atari color dot-matrix
4 = Epson monochrome dot-matrix
Printer port
0 = Parallel
1 = RS232 serial
Starting address of half-tone mask table (if 0,
use default ROM table)
Pointer to lstostat(), the PRN: device
output status function
Pointer to lstout(), the PRN: device
output routine
Pointer to autostat(), the AUX: device
status function
Pointer to auxout(), the AUX: device
output routine
Description
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