Service manual

Archimedes Serial Port
The Serial port on the Archimedes is designed for connecting a modem. As such any device connected to
the port must appear to the computer as a modem in order that the handshaking runs correctly.
The pinout of the port runs as follows
Pin 1 DCD Data Carrier Detect
Pin 2 RXD Receive Data
Pin 3 TXD Transmit Data
Pin 4 DTR Data Terminal Ready
Pin 5 Gnd Zero volts
Pin 6 DSR Data Set Ready
Pin 7 RTS Request to Send
Pin 8 CTS Clear to Send
Pin 9 RI Phone line Ringing
In order to connect a non-modem device, for example connecting an Archimedes back to back with a BBC
Micro, the normal arrangement of connecting RTS on one machine to CTS on the other, and RXD on one to
TXD on the other, should be used. Further to this however, DCD DTR and DSR need all to be tied together
in order that the system thinks there is a modem attached.
Further to this, at high baud rates, problems will arise if the Archimedes' own receive and transmit rates are
set differently. This is due to the RS423 controller chip only having one baud rate generator so when
different rates are required, problems arise. If either transmission or reception at a high rate ( > 4800 baud )
is required, it is important to set both transmit and receive rates the same even if only one direction is being
used.
FileStore Service
Central Service Workshop facilities have been made available at RCS for FileStore E01 and E20 units.
Please see later for the address of RCS. A service manual will be available shortly for those workshops
fishing to service the product themselves. The circuitry should not present any difficulties to those of you
a
lready involved with the service of BBC `B's and Masters - it is based on a 65C102 processor with two
ROMs and 64k of RAM. A circuit diagram of the FileStore E01 is enclosed for those workshops who may
wish to perform some work with the FileS tore before the service manual is available.
Doc. 999,0031 December 1987 -4- Acorn Engineering News