digital equipment corporation · maynard, massachusetts
A full description of the operation of the PDP-8/E front panel is in the PDP-8/E small computer handbook.

If you have trouble reading the Java front panel you can improve it under unix. If you make the window larger it will also look better. Clear pictures are available for either of picture for 640x480 screen or picture for 800x600 screen.  For printing a black and white version is available. With the current font handling in Java it is difficult to get good readable small fonts.

Values for the PDP-8/E are normally given in octal since 4 octal digits is 12 bits, the word size of these machines.  To convert octal to switch settings convert each digit using the following table:

0  000    4 100
1  001    5 101
2  010    6 110
3  011    7 111

Click on POWER in the lower left to turn on the PDP-8 and OFF to turn it off.  Power OFF    Power ON   Nothing can be done with the machine until power is turned on.  3-6 seconds after the power is turned on random lights on the front panel should come on
On the front panel when the switch register switches are down   they are 0 and when up   they are 1.  When a light is lit   it is a 1.  The values are entered on the switches in the same order written down, last digit goes in switches 9-11 etc.  The computer must be halted (RUN light off) by the HALT switch down before memory contents can be changed.

To load an extended address set switches 6-8 to data field to write to and 9-11 to instruction field to run from.  Then press and release the EXTD ADDR LOAD (EXTD on java version) switch.  For all normal uses they should be 0.  It is a good idea to set them to 0 if you have halted the machine and are trying to reload since the running program may have changed them.  The data field is displayed in the EMA lights.  To see the instruction field the rotary switch must be set to STATUS.  The lights above switches 6-11 will then display the fields.

To load an address set the switch 0-11 and then press and release the ADDR LOAD switch (ADDR on java version).  The address then should be displayed on the top row of lights.

To write to a memory location first do the previous load address step then set the switches to the value to write.  Then press and release the DEP key.  If you set the rotary switch to MD (memory data) the value written will be displayed in the second row of lights.   The memory address automatically increments, so to write to the next memory address set the switches again and hit DEP until done.

If you wish to read a memory location load the address then hit the EXAM switch.  If the rotary switch is set to MD the memory contents will be displayed on the second row of lights.

To start the machine running, load the address, set the halt and step switches to up, press and release the CLEAR (CLR on java version) switch and then press and release the CONT switch.  The run light should be lit.  The clear is not required but resets the processor state which some programs need to operate properly.

To see the accumulator value set the rotary switch to AC, some programs display patterns in it when idle.

For information on the rest of the settings see the small computer handbook.

For example, to load the RK05:

Set all switches to 0 (down)
click on EXTD
set switches to 0030  (000 000 011 000)
click on ADDR
set switches to 6743 (110 111 100 011)
click on DEP
set switches to 5031 (101 000 011 001)
click on DEP
set switches to 0030 (000 000 011 000)
click on ADDR
click on CLR
verify HALT and STEP are up
click on CONT

Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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