HRI Mode Puncher

The HRI Mode Puncher is a program designed for the PDP-9 computer, created on March 13, 1968, by the Software Services Group. Its primary function is to create paper tapes in Hardware Read-In Mode format from specified areas of core memory. These tapes are intended to be loaded into the PDP-9 using the console's READ-IN switch.

The program comes in two versions: a low memory version occupying registers 100-165 and a high memory version occupying registers 17400-17465. To use the puncher, the user places the appropriate tape in the reader, sets the console's ADDRESS switches to either 100 (low) or 7400 (high), and presses READ-IN. For punching, the user inputs the first address of the memory block to be punched into the AC switches and presses CONTINUE. After a subsequent halt, the last address of the block is entered, followed by another CONTINUE.

The Hardware Read-In Mode format represents each 18-bit memory word using three 8-bit lines on the tape. Channel 8 is always punched on each line. Crucially, if the ACSO switch is set to 1, channel 7 will be punched on the third line of the last word in a block. This signals that the last word should be executed as an instruction (e.g., HLT or JMP) immediately upon being read into memory, typically to terminate the punched area. Channels 6-11 contain the magnitude bits of the data. The program processes memory words by extracting high, middle, and low-order bits, combining them with the appropriate channel 8 (and optionally channel 7) signals, and then punching them sequentially to tape.