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OS/8 Disk Server Utilities

Kyle Owen - 9 Feb. 2014

This suite of programs allows anyone with a PDP-8/E or later to communicate with a modern computer running Linux, Mac OS X, Windows with Cygwin, or any other POSIX-compliant system where a standard C compiler such as gcc exists.


The software is provided "as is" without a warranty of any kind, either express or implied.

I encourage the use of this software in any non-commercial or commercial applications, but in fairness to other users and the developer, any changes for improving the functionality of this program should be documented for others to take note of.


Hardware requirements currently are a second M8650/M8655 asynchronous serial interface card or equivalent and the appropriate cables. The default address in the OS/8 handler is 40/41 (the default auxiliary TTY ports). This can be changed if necessary. On the modern computer, at least one serial interface is required to talk to the PDP-8's second serial interface. Baud rates have been used successfully to 230.4k baud.

Philipp Hachtmann's OmniUSB board has also been used successfully with SerialDisk. Future revisions will better support this board as well.

Software requirements involve loading the system and/or non-system handlers into OS/8 using BUILD. The modern computer needs to support the disk server, which is easily compiled with gcc. The PDP-8 assembly files have been built with David Gesswein's palbart assembler, as well as PAL8 under OS/8.

The disk server utilizes the standard dumprest/simh RK05 disk image format. These images are exactly 3,325,952 bytes long, which is 1,662,976 12-bit words packed in 16 bits per word. The first half of the image corresponds to side 0, and the second half, side 1. Typically, in OS/8 systems, SYS: is side 0.


David Gesswein's dumprest utilities for the PDP-8 have proved to be a tremendous help in the creation of the software herein. Thank you, David!


PDP-8 OS/8 Handler and Disk Server



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