MVME101 TERMINAL CONFIGURATION

Ray Robinson

Speech and Language Research Centre

School of English and Linguistics

Macquarie University

North Ryde 2113

NSW Australia

INTRODUCTION

The MVME101 is a VME bus 68000 single board computer card from MOTOROLA. It can be used as a stand alone processor or controller, or in conjunction with a disc controller and some memory, as a disc based computer. MOTOROLA can supply a system called the MVME315 kit which contains a MVME101 CPU card, a MVME201 256K DRAM card, a MVME315 disc controller, a boot PROM, and the VERSADOS disc operating system. The CPU card has 2 serial ports and 1 parallel printer port. The WYSE50 terminal has a smoothe scroll function which did not work with the MVME315 kit as supplied, so this is what is required for handshaking on the serial port. The terminal needs to control the speed at which the CPU is sending data, during the smoothe scroll, as the CPU can send much faster than the smoothe scroll speed, even the smoothe X8 mode (there are 4 smoothe scroll speeds and 1 jump scroll mode). The WYSE50 can control the CPU sending speed in 2 ways. It can stop the CPU by making the RS232 signal DTR go FALSE, and/or by sending control S (^S) the ASCII halt character (also called XOFF), on the serial data line. The CPU can then be told to start transmission by making DTR TRUE, and/or by sending control Q (^Q) the ASCII start character (also called XON). This is called XON-XOFF protocol.

XON-XOFF PROTOCOL

VERSADOS comes configured with control W (^W) as the start and stop character and a BREAK (^C) to abort the transmission. Use the SYSGEN utility to change this to XON-XOFF (^S^Q) and leave BREAK unchanged. Follow the SYSGEN example in the manuals, and copy all the relevant files to user area 9100 on the disc. (My COPY utility has a non operative C option, so I had to rename some of the files to VME101). Then edit the file 9100.VME101.SYSCMD.CD to change the variables: TCP$XOF to hex 13 (^S the XOFF character), TCP$XON to hex O (this allows any character to start transmission including ^Q), and leave TCP$BRK as hex 3 (^C the ASCII BREAK character)(you can change it if you want to). Change the logon message REVNUMBR to 4.3:a to indicate the change. Copy the new VERSADOS.SY to area 0000 and reboot. The smoothe scroll now works nicely at all 4 speeds and the listings can be stopped with ^S and started with ^Q (or any key) and aborted with BREAK (^C). I also made another version (4.3:b) which uses ESCAPE-ESCAPE as my FLEX system does, to see if I liked the old familiar control sequences.

DTR CONTROL

The RS232 cable should be wired as in Diagram 3. When the WYSE50 uses the DTR signal only, then VERSADOS responds with a DEVICE NOT READY error! The same file we edited before, gives a clue to the problem. The parameter TCPSCTRL allows the use of the RS232 CTS signal to control the transmission. Figure 4.9 of the MVME101 M68000 MONOBOARD MICRO COMPUTER USER'S MANUAL sheet 8 shows that the MC68661 EPCI (Enhanced Programmable Communications Interface) (ACIA or UART to me) chip U52 has 2 patch areas for the RS232 signals but will force CTS and DTR to be connected together. Change the card such that the control signal from the terminal only goes to CTS on the EPCI. The changes involve cutting 2 tracks, adding 2 pieces of wire, and repatching. First locate the track which goes from U58 pin 11 to U52 pin 22, and cut it near C35 next to U52 pin 22. Then under the socket of U52, the track continues from U52 pin 22 to patch area K9 pin 6. Cut this track under U52. Using a piece of thin insulated wire (wire wrap wire is ideal) join the track before the first cut to after the second cut. Check with an ohmn meter that U58 pin 11 goes to K9 pin 6, and does NOT go to U52 pin 22. See Diagram 1. Now connect U52 pin 22 to the earth end of C35. Check with the ohmn meter. So now DTR on the EPCI is earthed, giving permanently TRUE status, and the terminal control line goes to patch area K9. Diagram 2 shows the patching on K9 to connect CTS on the EPCI to the buffer U58, and the patching on K7 to connect the RS232 plug P3 pin 20 (DTR) to the buffer U58 pin 13 (CTS). Diagram 3 shows the RS232 cable connections between the WYSE50 and the MVME101. Go into the setup menu and set the WYSE50 to use DTR control only. When a listing now occurs, the terminal's DTR control line is connected to the EPCI's CTS input and the smoothe scroll works fine.

REFLECTIONS

I don't use the smoothe scroll much but it is handy for scanning listings. However, the exercise is useful in becoming familiar with the SYSGEN utility and examining the features of the VERSADOS disc operating system. The MVME101 processor board now has the facility to control the CPU sending speed by XON-XOFF protocol (or any other character protocol). Not only does the system allow smoothe scroll, but this will allow serial printers using XON-XOFF to be connected, and communications programs which use character protocol to function. The system also allows control of the CPU sending speed electrically by the RS232 signal DTR (or CTS). The smoothe scroll can also be controlled by the DTR line and a serial printer using electrical control can now be connected to the other port (if similar changes are made). Since the DTR control now works, I can use the FLEX ESCAPE/ESCAPE control of listings if I wish.