ACT apricot - Channel B Programming Details

SERIAL INTERFACE
Keyboard Connector Pin Definition
Pin
Description
1
+ 12V Out via a 4.7 ohm series resistor.
2
Serial Data Out.
3
Serial Data In.
4
OV.
5
N.C.
6
Frame Ground.
7
-12V Out via an 100 ohm series resistor.
8
OV.
9
N.C.
9-PIN D-TYPE fEMALE
5
Figure 2. Keyboard Connector DetaH
Channel B Programming Details
In addition to providing a series of Write Registers to
configure the SIO to interface with the keyboard, a number
of other parameters and control features are also
programmed through channel B. These include:
(a) The base address for the SIO interrupt vector.
(b) Enabling and disabling of the Parallel Interface
interrupt control input lines.
(c) Selection control for the baud rates for the RS232C
channel.
The parameters issued to the Write Registers of channel B
for interfacing
the SIO to the Keyboard, and the interrupt
vector base address are programmed during an initialisation
routine by the BIOS. These are fixed and never require any
modification by the software. The control bits for the
Parallel Interface interrupts and selecting the baud rates for
the RS232C channel are set to default states during