Most PDP-11's have a serial console monitor. This is a simple line based user interface which allows to write, read and execute code.
This is important
- if you need to boot device which the Boot ROM is missing. Then you have to enter the boot loader code over monitor.
- if you want to run diagnostics, and have no working disk or tape devices yet.
Many many people have written auxillary programs to automate code download. Here comes my contribution: "pdp11monloader".
It is a command line program, written in C for Linux platforms. On MS-Windows it can be compiled for CYGWIN.
- serial port, baudrate and data format settable
- can work with QBUS-PDP-11's (ODT monitor) and with UNIBUS machines (M9312 / M9301 console emulator).
- can load code from MACRO-11 listing files, standard paper tape images and plain textfiles with octal <address> - <value> pairs in each line.
- can start execution of downloaded code
- can stay in primitive tty-like terminal emulator to let you immediately work with the running code.
Download here: https://github.com/j-hoppe/pdp11monloader. The "demo_files" contains some example code formats.
More info by built in help: https://github.com/j-hoppe/pdp11monloader/blob/master/README.md