Vaisala SPT11A reader (was Data General Nova Star Trek)

Paul Birkel pbirkel at
Tue Apr 26 05:01:18 CDT 2016

Thanks Erik; very helpful.  For reference, mine also shares the same
firmware revision.  Can you share your source code as well?

-----Original Message-----
From: Erik Baigar [mailto:erik at] 
Sent: Tuesday, April 26, 2016 5:33 AM
To: Paul Birkel
Cc: jwsmail at; cctalk at; shermanfoy at
Subject: Vaisala SPT11A reader (was Data General Nova Star Trek)

Dear Paul,

thanks for your email - I acquired the reader several years ago and did
quite a lot of experiments to figure out how to use it with the original
firmware SPTS11, 2.02, 5289 but I never got an answer from the reader. So
the project of Jim to read in the DG tapes was the reason I needed to
address this issue. For your (and the communities) convenience I placed the
original firmware (27C256 type EPROM)...

...and my new one (also 27C256)...

...onto my server. My new firmware just sends out the data read via the
serial port at 9600, 8N1. A welcome messages tests the serial communication
on starting and during this time the red LED is on.
On getting ready the green LED takes over and the yellow one shows the state
of the sprocket input: For each byte read this LED flashes. At 9600 the
serial port is always faster than you can pull the tape through the reader,
so I do not expect the red LED (indicate a buffer overflow, byte lost) come
on during normal operation...

The pinout of the Sub-D9 male plug is as usual on serial ports:
5: GND, 2: Data from reader to PC, 3: Data from PC to reader (not used in my
firmware, but original expects some start/config command here) additionally
7: DC input to reader (in my case 9V).

    Hope this helps,

       best regards,


On Tue, 26 Apr 2016, Paul Birkel wrote:

> Eric;
> Would you please share your firmware updates, and any other 
> information that you've gleaned regarding the Vaisala SPT11A reader?  
> I recently acquired one of these as well but haven't yet started on 
> reverse-engineering it into something useful  Would prefer to leverage 
> your experience, if you please :->.
> Good health to You and Yours!
> paul
> (from Maryland, USA)
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Erik 
> Baigar
> Sent: Monday, April 25, 2016 11:42 AM
> To: jim s; cctalk at
> Cc: Sherman Foy
> Subject: Re: Data General Nova Star Trek
> Hi Jim,
> regarding reading the StarTrek paper tapes I spent some time on the 
> weekend to rework my SPT11A manual reader - I got this from an eBay 
> auction and it was an accessory for some military receiver (probalby 
> to read in some codes). It had a fimrwaere which refused to 
> communicate with a simple terminal program, so I reverse en- gineered 
> the hardware and replaced the original ROM it by an own firmware which 
> simply sends the contents read from PPT to the PC via its RS232C...
> So I'd offer sending this to you as an item on loan to read in your 
> tapes and you return it afterwards? I tested it with some data and it 
> works well (just slowly pull the paper tape through the reader and use 
> e.g. putty to log the binary serial output). After turning on the 
> reader there is a short welcome message to verify the serial connection
> The only question is, whether you can handle the EU style power supply 
> shown in the picture...
> I ordered USB->RS232C converters and if you have some more time, I'd 
> attach one of them to the reader not only doing conversion but also 
> supplying the converter with power from the PC.
> Addidionally you should send me your physical address via PM so I can 
> prepare for shipping...
>    Best regards from Germany,
>       Erik.
> -----

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