Radstone PME 68-1B, Manual

Page: 27 / 132

Address Assignment - Remote Interface
Address Mode Description
0C0101 R Status Register
0C0101 W Control Register
0C0103 R Receive Data Register
0C0103 W Transmit Data Register
Host Interface
Port 2 (connector P3) may be used for up/down loading of user programs and data, using
the Monitor Dump/Load command, or in the transparent mode, to interface the
terminal connected to Port 1 (connector P4) directly to a host computer.
In the configuration diagram Figure 6, both the PME 68-1B and the host are set to re-
ceive data from the terminal on the Transmit Data Line (TXD) and echo it via the Re-
ceive Data Line (RXD) back to the terminal. The PME 68-1B polls the terminal ACIA
registers.
A standard method of communication between the terminal connected to P4 and a host
computer is known as ‘Transparent Mode’. In this mode all transmitted characters are
sent directly from the terminal to the host computer and no correction or modification is
done by the PME68-1B. Figure 7 is a schematic of this configuration.
When the user types a valid stop character sequence, the CPU recognises it, stops
transmission of the following characters from the terminal to the host computer and re-
turns the system to the Monitor program. The stop character sequence is therefore the
last sequence that the PME 68-1B board sends to the host.
The baud rate of each module, terminal, PME 68-1B terminal interface, and host
computer interface must be set to the same level. The baud rate of the host ACIA can re-
main unaltered as the transparent mode does not use this ACIA for transfers.
The host interface can interrupt the PME 68-1B CPU on level 2, the interrupt vector
used is the auto-interrupt vector (# 26/$000068). If a connected device cannot drive the
CTS signal high, a connection must be made between pin 5 and pin 20 of connector P3.
A detailed description of the data format and Dump/Load (DU/LO) commands is given
in Chapter 5 for the PME68/Monitor and in the separate PLUM manual for the PLUM
monitor.
PME68-1B Manual
Page 21 Issue 5