rricharz / tu77

TU77 magnetic tape on-screen emulator for SimH and PiDP-11

TU77 magnetic tape front panel emulator

Simulation of a TU77 and a Te16 magnetic tape front panel for SimH (PDP-11). The TU77 and the Te16 did of course only work properly if the vacuum columns were closed, but it is much more interesting to see how the tape moves in the open vacuum columns.

Vacuum column tape drives are described on Wikipedia - nine track tapes.

For the Raspberry Pi and other Linux systems.

Video of a TU77 demo showing tu77 in action on a PiDP-11. Video of a TE16 demo showing te16 in action on a PiDP-11.

The TU77 magnetic tape unit had a very fast tape transportation speed for reads and writes of 3.2 m/s, and a rotation speed of the reels of up to 500 rpm.

A driver to use tu77 and te16 with the PiDP-11 is included.

Hardware requirements

This TU77 and TE16 simulator has been tested on the PiDP-11 using a Raspberry Pi 4B. A considerable effort has been made to reduce the CPU usage to acceptable levels. It should therefore also work on Raspberry PI 3B and Raspberry Pi 3B+ models. Please send your positive or negative feedback on using tu77 on Raspberry Pi 3 models to [email protected], so that I can update these requirements.

Slower Raspberry Pi models are not recommended.

Download the program

I recommend using "git clone" to download the program. This allows for very easy upgrades.

  sudo apt-get update
  sudo apt-get upgrade
  sudo apt-get install git
  cd
  git clone --depth 1 https://github.com/rricharz/Tu77
  cd Tu77

To upgrade the program later, type

  cd
  cd Tu77
  git pull

If you want to recompile the program, proceed as follows

  cd
  cd Tu77
  sudo apt-get install libgtk-3-dev
  touch tu77.c
  make

Start the program with

  cd
  cd Tu77
  
  ./tu77

The following keys can be used to exit from tu77 and close the corresponding window. These keys are especially useful in full screen mode where no close window button is available.

• ESC
• ctrl-C
• ctrl-Q

Buttons

The only active button is the "ONLINE" button. If you toggle this button in the offline position, the online light will turn off and the drive will not listen to SimH anymore.

Demo of tape write

There is a small demo program which demonstates reading from tape. It is also a test for the communication between a simulated "host" (the demo program in this case) and tu77.

Start tu77 in background (with the &) using

  ./tu77 &

Start the demo program with

  sudo ./demo

Sudo might be required if SimH has written to the status byte file before.

If you abort the demo program while it's running you might end up with reels spinning forever. Just use

 sudo rm /tmp/tu56status

Note: The status file is called tu56status, because it works both for the tu77 magtape front panel emulator and the tu56 DECtape front panel emulator.

Simulating a TE16

There is also an emulation of a TE16 tape drive including. Start the TE16 emulation with

 ./te16

Installing the proper driver in SimH

A slightly modified tape driver needs to be installed in SimH. This driver writes the necessary status bits into a little status file, where it can be read by tu77.

There is currently only a driver for the PDP-11 available:

• magtape driver for the PiDP-11

Instructions for different operating systems

• Using tu77 with 2.11 BSD on the PiDP-11

Improved instructions are very much appreciated. Please send improved versions of these instructions, and instructions for other operating systems to [email protected]

Options of the command tu77

tu77 has the following options:

-full		start tu77 in a full screen window
                    
-fullv          start tu77 in a decorated window using the maximal vertical space
		available.

-unit1		attach to tape unit 1 instead of unit 0

-label "text"	show a blue label on the removeable reel with the specified text

Versions

See versions

Contributors

Johnny Billquist, Neal G., Terry Kennedy and Jonathan Morton have helped to understand vacuum magnet tape motions. The pictures of the open TU77 have been obtained from Henk Gooijen. The picture of the open TE16 has been obtained from https://commons.wikimedia.org/wiki/File:9-track-drive-open.jpg#mw-jump-to-license. Thanks to all others who have helped to develop this software.

The usual disclaimer

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.