PCjs Machines

DEC PDP-11/20 with Bootstrap Loader

The machine below pre-loads the Bootstrap Loader code into 16Kb of RAM:

<ram id="ram" addr="0x0000" size="0x4000" file="/software/dec/pdp11/boot/bootstrap/BOOTSTRAP-16KB.json"/>

and then pre-loads the Absolute Loader tape image to the PC11 Paper Tape Reader:

<device id="pc11" type="pc11" baudReceive="9600" autoMount='{PTR:{path:"/software/dec/pdp11/tapes/absloader/DEC-11-L2PC-PO.json"}}'>...</device>

Click Run to load the Absolute Loader. When the Bootstrap Loader is finished, it will HALT, leaving the Absolute Loader ready to run immediately after the HALT.

You can then select another tape image in the Absolute Loader format, such as BASIC (Single User), click Load and then Run.

If you need to start over, select “Bootstrap Loader (16Kb)” from the list of tapes and click Read instead of Load, re-installing the Bootstrap Loader directly into RAM.

Alternatively, just press the Reset button. The RAM component was recently updated to restore pre-loaded images whenever the entire machine is reset. You’ll still need to manually reload the Absolute Loader tape image, however.

This machine is also available with our built-in Debugger.

[GitHub Source]