Vaisala SPT11A reader (was Data General Nova Star Trek)

Erik Baigar erik at
Tue Apr 26 04:32:47 CDT 2016

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

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 (9600,8N1).
> 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.
> -----

More information about the cctalk mailing list