ACT apricot - Description; General

SELECT
r--""l r----'O.25MHz
I ~"s'l:Z I--f>I DIVIDER
I PARALLEL
: INTERFACE
PERIPHERALS DATA IUS
SYSTEM CONTROL BUS
DECODER
SID SELECT ---~ C£
AZ B"A
Al VD
fRlIM CLOCK [peLf<
GENERA TOR RES
SERIAL INTERFACE
W/RDYA
280
SIO/O
hDI
TO DRQi! Of lDP
RS232C
CONNECTOR
Rx CLOCK
Tx CLOCK
Tx DATA
Rx DATA
RTS
DTR
DSR
CTS
DCD
KEYBOARD
C]'f'lECTOR
DATA OUT
DATA IN
HARDWARE RESET ~)
TO CLOCK GENERA TOR
TO IRS Of INTERRUPT
CONTROLLER VIA Art
INVERTER
Figure 1. Serial Interface block diagram
DESCRIPTION
General
The Serial Interface consists of; a serial input/output
controller, a data selector, a number of line drivers/receivers
and two connectors (a 25 pin D-type female connector for
the RS232C channel and a 9 pin D-type female connector
for the keyboard link).
The major circuit element of the Serial Interface is the
serial input/output controller which is a Zilog Z80 SIO/O.
The SIO is a programmable device which incorporates all