Programmer Electronic Control - Airborne Computer...

Erik Baigar erik at
Sun Jan 1 06:55:39 CST 2006


via eBay I got a small computer which I analyzed and 
reverse engineered in the last months. I got quite far
and last week I came across an old thread in this group
initiated by William Maddox in nov 2003 where he mentioned 
the unit:

"RAF Tornado Computer with Core Store Memory  
       ... eBay-link cut out ...
A small airborne computer.  From what look like
date codes on the components, it looks like it was
made in the early 80's, which seems a bit late for
this technology."

The seller had several of these units for sale. My
question is wether anyone reading this group has
probably acquired one of the units and is willing to
share parts and/or information?
Up to date I bulit a setup around the box consisting 
of a logic analyzer connected to many vital signals. 
A modified transputer board connected to a Sun Sparc
20 allows to read and write the core memory of the 
small computer. The box is a 12-bit machine with 
8K words of memory. It has a 13-bit program counter 
and a 12bit accumulator register. Memory organisation
is similar to PDP8. The cycle time is 1.2us and 
the complete memory of the box I have is functional. 
In reverse engineerineering the command set I dis-
covered JUMP and a ADD command - So I am already able
to write very simple programs for the box. 

But now lot of commands cause the CPU to freeze (even 
a reset cannot restart it - one has to power off and
on again) and I cannot believe that such commands exist 
in a computer of this type. Maybe there is a defect 
located in the function-decode-board which contains 
the microcode in several small PROMs. It would be 
V E R Y  helpful if one out there could at least 
borrow me his boards for a crosscheck (I do only need
SK7 and above, not the core memory boards).

Regarding William Maddox's comment about the date 
of the box: Regarding the architecture the box is
very similar to PDP8 but mine has been built after
6/82 with the power supply been changed after 1982.
This type of box was indeed developed for the 
tornado but - as far as I was able to find out - 
was not used. It might have been some kind of
prototype device. Serialnumber is <50. The boards 
for core memory seem to be somewhat universal 
and even older in design - maybe they have been
used in other devices, too...

   Any hints are welcome,

       best regards,

           Erik, erik at

P.S. For pictures see

More information about the cctech mailing list