Talking to Mainframes Era Reel to Reel 9 track tape drives

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While wondering in some abandoned space you stumble into a room filled with a mainframe from the 1970s-era and first thing flowing through your head is to turn on this monster. 9 track tape drives are fun to tamper with. The interfaces of those era were either UNIBUS, HP-IB or PERTEC Industrial Standard. The last one survived until the middle of the 90s and was adopted as a de-facto standard for industrial machines using tape drives. In order to keep compatibility, Pertec Formatters were built. The Pertec Computer Corporation (PCC), formerly Peripheral Equipment Corporation (PEC) also created their own version of Floppy Disk Drive Interface which was later adopted as a standard and survived until the 2000s when it was removed from computers.
This project consists of building and experimenting a microcontroller-based device to interact with tape drives. For the moment - reading tape data,storing it to SD-Card, write data from SDCard to a new tape. Later - becoming the drive itself.

Here are the steps:

[2009] acquired a 9 track tape drive;
[2010] recovered a communist-era Digital Alpha Numeric Terminal vt100-compatible;

[2013] found an old mainframe and brought it home part by part. Also communist clone;

[2014] acquired the second tape drive - power supply broken;

[2018]  Restoration project started

First step - getting the tape drive working.

This project aims to build an interface between modern and old tech. In order to get the monster working I need whatever data I can get: operating system, backup tapes, software, floppy disks, anything.

Industrial 9 track Tape Drives talk Pertec and this is the interface I am going to focus for now. So these are the functions:

1. PERTEC (9 track tape physical drive) to MicroSD Card (host microcontroller) converter - read/write data from/to tape;

2. PERTEC Drive Emulator (micro-controlled sd-card) to Mainframe (host) - acting as a genuine 9 track tape drive peripheral;

3. PERTEC (9 track tape physical drive) to SCSI (host) Converter - some people decide these devices should cost a ton of money and I want to have some fun by telling a little bit of their secrets;

4. 9 Track Tape-based USB Drive - a big, huge, mega useless mass storage USB.... wooden-stab or stick - just for fun.

My English is not too good due to the lack of good quality beer in my city, but you will get the idea:

PCB and experiments will come later.

In the mean time I'm getting my brain cooked at  while reading tons of documentation about anything related.


The Pertec Whisperer - PCB Prototype 1

JPEG Image - 4.59 MB - 04/15/2018 at 11:33



Connections to the Pertec Interface: input/output from host (when acting as peripheral), input/output from Tape Drive(when acting as a host)

JPEG Image - 1.64 MB - 04/15/2018 at 11:33



Microbrains interfacing schematic. We can consider this PCB as a huge Arduino shield.

JPEG Image - 1019.81 kB - 04/15/2018 at 11:33


  • 1 × 1970s era mainframe Romanian, Bulgarian, Eastern Germany or Soviet-Union made if you find it in the Eastern Europe. Rough and tough, hard to repair, reliable when you get it working.
  • 1 × 9 track tape drive Western Europe or USA-manufactured - preferred. Big pain if you get the communist variant.
  • 1 × STM32 development platform Get as many GPIOS as you can
  • 1 × Arduino...whatever Any of them able to handle 8-bit ports. Arduino Due is extremely fast but the physical ports are a mess. However the ATSAM3x8E by itself should be a treasure

  • Awaiting offer from local PCB manufacturer

    [skaarj]4 days ago 0 comments

    I have my own tip line on Eastern Europe PCB Manufacturers.

    Romania - PCB Electra -

    They manufacture industrial PCBs - single sided, double sided and also multi layer. And they are cooler than OSH-Park or Eurocircuits because these guys can handle serious stuff - from 4 up to 24 layers!

    I sent them the PCB project for review. More news when I have a reply.

  • PCB - first prototype

    [skaarj]6 days ago 0 comments

    Work is done

    Awaiting reply from some manufacturers. OSHPark has no plans yet to multiply 10x their profits by coming to Europe. I went on their web site -three of these PCBs cost me around 200$ per total which is cool - but I have no wish to pay to fullfill some Ministery of Coruption and Stealing abusive fees on work&research in customs.  

    Eurocircuits is the second choice. A little more expensive and PCB is coming in two weeks. I want this done fast so I can start with the software as soon as possible. 

    I am considering two options:  some local PCB manufacturer which will make one of these in 5 days for around 100US$, or I will do it myself using my old CNC and tons of patience.

  • Central Processing Unit

    [skaarj]6 days ago 0 comments

    This is the classic Arduino.  8 bits architecture is required to keep things as simple as possible - just because the PERTEC communication protocol is a real pain. It is documented on bitsavers on all those PDFs gathered by the willpower of our digital forefathers. Documenting this is still work in progress, as I have to read everything from beginning to end. Some PDFs have hidden surprises which the rest do not tell. These secrets are well kept.

    Added 512kB RAM for buffering the transfer.

  • Pertec I/O interface schematic

    [skaarj]6 days ago 0 comments

    There are two connectors:  the two classics - P1 and P2 - and the DB62F. Whatever is connected there is the user wish:  either the tape drive or the pertec controller. To keep things simple, these two are not supposed to be online at the same time. If acting as a host, only the drive itself should be tunrned on. If acting as a drive, the tape drive should be switched off. You got the idea.

View all 4 project logs

  • 1
    Find an old mainframe

    Stealing it is excluded due to its huge size. Try to negotiate.

  • 2
    Bring it home

    Transport may be a problem but it can be done.

  • 3
    Start hacking

    Remember to gather as many boxes of documentation as you can. Get all the tapes, all the floppies, all the manuals, papers, folders, no matter if they look perfect or they are eaten by rats. 

View all 3 instructions

Enjoy this project?



Starhawk wrote 4 days ago point

Well this is about as cool as liquid nitrogen :D

Good luck! +Like, +Follow.

  Are you sure? yes | no

Arnaldo Pirrone wrote 04/13/2018 at 13:16 point

Hi, about 3 years ago, something has been done with PERTEC tapes.

If it could be of any help:

  Are you sure? yes | no

[skaarj] wrote 04/13/2018 at 15:44 point

Thank you. I know about the experiment, I even talk to one of the hackers involved in this project. What they did is set the drive from internal jumpers into service mode to forward the tape until the end. During this time, a data logger was connected to all the 9 signal amplifiers. The resulted data was processed further and they managed to rebuild many tape images successfully. .

They concentrated all their effort on data recovery. Talking to the drive using its interface was not part of their project. This is where I am trying to push the frontier.

  Are you sure? yes | no

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