Serial/Parallel Input/Output Tables - Zenith Z-100 Reference Manual

Serial/Parallel Input/Output Tables

O
Figure 8.1 graphically illustrates the format for the serial and parallel device param-
eter mapping.
This is the table vectored to when a device is configured using the MS-DOS
CONFIGUR program, but the parameters contained in this area of memory may
also be changed by the user to suit his own unique device requirements.
A default value is contained in ROM to cause program branching to this table
when a parallel interrupt, 17H, or a serial interrupt, 14H, is received. However,
both the jump vector and the location of the table may be changed if desired.
Up to three parallel devices, and two serial devices, may be configured. In addition,
a parallel device may be mapped to a serial device.
PARALLEL
DEVICE + 1
PARALLEL
D EVICE + 2
PARALLEL
D EVICE + 3
SERIAL
D EVICE + 1
SERIAL
D EVICE + 2
Figure 8.1. Serial and Parallel Device Layout
Serial and Parallel Input/Output
R OM ENT R Y
FROM
INTERRUPT 1 7 H
ROM ENTRY
FROM
I NTERRUPT 1 4 H
Page 8.3