Looking for a Depraz mouse.

Jules Richardson julesrichardsonuk at yahoo.co.uk
Mon Sep 24 08:08:39 CDT 2007

Tony Duell wrote:
>> Mine are both that type (quadrature), but with the same connectors as found on 
>> the BBC micro's User port. However, whilst they appeared originally to be 
>> wired to conform to that port's pinouts (i.e. no TTL outputs shorted to ground 
> Do the power connections make sense? IIRC, the BBC micro user port has 
> one row that's 2 power and 8 grounds, the other row is port B of a VIA + 
> its control lines.

Sorry for late reply...

Mine were wired as follows:

     pin       function
      1        +5V
      6 (PB0)  Middle button
      8 (PB1)  Left button
     10 (PB2)  Right button
     14 (PB4)  Y1
     16 (PB5)  Y2
     18 (PB6)  X1
     19        GND
     20 (PB7)  X2

Whereas the typical pinout for mice on a beeb seems to be one of:

     pin      Variant A   Variant B
      1         +5V         +5V
      2 (CB1)   X1          X1
      4 (CB2)   Y1          Y1
      5         GND         GND
      6 (PB0)   X2          Left
      8 (PB1)   --          Middle
     10 (PB2)   Y2          Right
     12 (PB3)   --          X2
     14 (PB4)   --          Y2
     16 (PB5)   Left        --
     18 (PB6)   Middle      --
     20 (PB7)   Right       --

... variant 'A' is the more common AMX/Quest/Acorn mouse pinout. So in the 
case of my Depraz ones, yes the power signals were OK (as all odd pins > 5 are 
GND on the User port IIRC), but the signals were all completely different 
(pin-wise) to either of the two 'standards'.

I'm not aware of any Model B / Master software which came with a Depraz mouse 
- presumably they were quite expensive critters too, implying that the 
software was perhaps something high-end. Either that or they weren't tied to 
anything specific, and just sold along with some programming information.

>> They're not particularly nice mice to use IMHO - but they are rather cool 
>> compared to the boxy alternatives around that time (although I suppose my 
>> Penny & Giles mouse dates from about the same time, and that one's far nicer 
> I think I have one of htpse Penny and Giles mice somewhere, and IIRC it 
> has a 20 pin IDC socket on the end which I presumed was for a BBC User 
> port...

Yep, mine's the same... I'd originally assumed it was for an ACW (as according 
to folklore their optional mouse was a P+G) but I'm not sure what the standard 
mouse port was for an ACW with the mouse board (I've got an ACW here with the 
mouse board fitted, but with no wiring to any socket on the rear panel) - I 
should have a look at the service manual and your reverse-engineered data 
sometime to see if that gives any clues...

> I have a very nice trackball from about the early 1980s. Not only does it 
> hacve the ball and 4 function buttons, but also 'arrow keys' that when 
> pressed generate the apporproate quadrature waveforms (as if you were 
> rolling the ball in that directuon), at a switch-selectable rate. 

Nice. All I've got here are the bog-standard Acorn/Marconi ones (the RB2) - 
although the Marconi one is still in its box and seems to have no hours on it, 
judging by the fact the spindles haven't worn like they normally do!



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