MTED Author: Steve C. Cribbs June 1984 Atomic Energy of Canada Limited Pinawa, Manitoba Canada R0E 1L0 MTED was written to allow dynamic redefinition of use for the RT-11 multi-terminal ports. Although RT-11 permits a program to blindly use a device handler, interrupt service routine or directly address the vectors and registers that control a multi-terminal serviced port, it is a foolish practice that destroys the monitors integrity. Once the port's CSR and vectors have been modified, the monitor has lost control of the device. Further use of the port as a terminal may hang or corrupt the system. Of course, proper service is restored when the computer is re-booted. The Multi-Terminal Enable/Disable utility (MTED) can be used to inform the monitor that the port is unavailable, turn off input interrupts, and to also preserve the necessary vector linkage to the monitor's terminal service code. When terminal access through the port is again desired, MTED can restore proper linkage. Like the RESORC utility, MTED can be used to indicate terminal availability, but in addition MTED also returns information through the systems User Error Byte. This last feature is very useful to tasks executed through command files. MTED provides an asterisk ("*") prompt as do DIGITAL's utilities and is terminated by the CONTROL_C sequence. It responds to four commands: DISABLE, ENABLE, LIST, and HELP. Single character command abbreviations are recognized. The first three commands accept a list of numeric arguments indicating the multi-terminal port numbers to be acted upon. Argument lists may be separated with either space or comma characters. The LIST command with no arguments displays a table of CSR and vector addresses for all enabled ports. Information saved through the DISABLE command is written into "SY:MTED.SAV", thus this program should be run from the system device. MTED reports errors for the following conditons: - specification of an illegal multi-terminal number; - attempts to disable: - an already disabled port; - a port in use by another job; - the job's own console; - attempts to enable an already enabled port.