Operating commands

The first time you load MCP you will be greeted with the following display:

R TIME IS 0000
I TR1001
R TIME IS 1001

The in front of the line is typed by the simulator. On the original Burroughs B5500 the console was a half duplex device. In order to enter data into the system, the operator needed to press the Input Request key. This interrupted the system which would light the Ready light. After the operator was done entering the message he would press End of Message. On the simulator this is simulated by the Escape key. This is equivalent to the Input Request key on the console. When the system is ready to receive input it responds with and waits for the user to type input. When done typing a message press the Enter or Return key to simulate the End of Message key. This will send the message to the system. Backspace can be used to correct mistakes. Pressing Escape again will abort the typing.

MCP puts a # before commands that require a response. It will continue periodically to repeat the question until the user answers. The system will generally ask for the time and or the date. These can be controlled by options. See the section on Cold and Warm Boot decks.

In the message above, MCP announces itself and indicates that it started with a Halt/Load. Then which MCP was loaded. MODS indicates which memory modules are online. Generally this will always be all R's. For the initial load MCP will report each Storage unit attached to the system. Finally it prints what it believes is the time and date. MCP will not do anything until the date and time are set. So press Escape and at the prompt enter TR hhmm<return> to set the time and get MCP to work.

If there is input attached to the card reader MCP will start reading them in. Otherwise attach a deck to the card reader to run jobs on MCP. Do this by Pressing Control and E to interrupt the simulator. SimH will print a sim> prompt. Type attach cr0 deck to attach a deck and continue to continue the simulation. MCP will then report BOJ and EOJ messages as jobs are started and ended. Some jobs use what are called PSUEDO-READERS, it is generally a good idea after starting MCP to enable a ew of these. You can do this with the RN# command. Typically RN2 is a good number.

MCP runs jobs from what it calls the MIX. To find out what jobs are running you can use the MX command.

Some useful commands, for a complete list see Operating the B5500 Time Sharing System.



CC <control information>

Starts a job from console.


Starts time sharing.

CI <file>

Sets the current intrinsics file.

CM <file>

Sets the next MCP to run at boot time.


Displays amount of memory used by the jobs in the current mix.

<mix index> DS

Terminate a job in the mix.

DT <integer>/<integer>/<integer>

Sets the date.

MF #

Changes TSS space used to #. Default=16348.

MU #

Changes maximum number of time-sharing users that can be logged in a one time


Prints out a list of currently running programs.

PD =/=
PD <file>/=
PD <file>/<file>

Lists files on the disk.

<mix index> RM

Allow job to overwrite an existing file.

RN  #

Specifies the number of Pseudo readers to run.

RY device

Resets device.

SF <fractional value>

Indicates the amount of memory to allow the system to take.

Basic Messages

Basic messages from the system consist of several formats.

<program name>=<mix index>

Identifies that the message is from the given program at the specific mix. Common messages are BOJ, EOJ indicating that the job is starting or ending.

Messages that start with # indicate that the system needs some information to continue.

If you see a message like:

#NO FIL <name>

You will have several choices to respond to this command. You can attach a tape with <name> label on it. If the program is trying to create a file you can attach a blank tape and do PB MTx to declare the tape as blank. The system will grab the first blank tape for this. If you don't have a file/tape then you will be forced to DS the job which will kill it.

#DUP LIBRARY  <file> : <mix index>

This message occurs when a job tries to overwrite an existing file. You can either rename the file to another name, or remove it and enter <mix index>OK message. If it is ok to delete the file you can enter <mix index>RM which will remove the file and let the job continue. If there is some error you can <mix index>DS to abort the job.

# MT RQD  <file> <rdc> : <mix index>

This message indicates that the job is looking to write a file to a tape, and you should mount a blank tape on an available drive and issue PB MTx.

If you want to enter a command to be executed from the operator console you can use the CC command. Multiple commands can be separated by ;'s the last command should be END. The system will continue asking for input until the END card is given.

When jobs fail you might see something like this displayed:


This indicates that the stack pointer was moved below it's limit. You can try increasing the stack size of the job or checking for programming errors.

Other errors that might be reported may have S= #, A=#, ... this indicates the line that caused the failure. If you look at the listing, you will see Segments listed, the S=# gives you the segment number to look at and the A=# gives you the address within the segment where the fault occurred.

Starting Time-sharing

To enable time-sharing if the system was set up to run DCMCP, boot into the system and after entering time and date, enter:


MCP will tell you that this is to be the next MCP run. You can reboot now. You will now get this prompt.

TIME IS 1526
TIME IS 2218

Next change the intrinsics file to TSS/INT with:


To start timesharing you need to enter the CE command. This will display the following:


At this point you can telnet into the port you have set in xiii_run.ini file.