Summagraphics tablet?

From: der Mouse <mouse_at_Rodents.Montreal.QC.CA>
Date: Wed May 5 02:34:34 2004

[I wrote]
>> Does anyone know, or know of a reference to, the serial-line
>> protocol spoken by Summagraphics tablet digitizers (specifically,
>> the MM1103)?

[John Honniball <coredump_at_gifford.co.uk> replied]
> I have two Summagraphics manuals, for the "Bit Pad One" and the
> "MM2101 and MM961 Data Tablets". They both list protocols, bit
> rates, DIP-switch setting and so on.

> Perhaps the Bit Pad One manual would be the one to look at?

Maybe. But see below.

[ard_at_p850ug1.demon.co.uk (Tony Duell), responding to the same message
of mine]
> The Sumagraphics Bit Pad 1 was a very common tablet at one time.
> From waht I remember, and I do have the manual _somewhere_ (this
> being a real manual which documents the data format and includes
> schematics), there were 2 output formats. [...] Which you got was
> set by a DIP switch inside.

> Another switch turned on streaming mode [...]. I think that's the
> mode you're asking for,

Right.

> I would guess you need to find the right DIP switches inside, which
> are doubtless different to those on the Bit Pad 1

Quite likely.

I have the thing opened up right now. There are 24 DIP switches, three
banks of eight, labeled SW1 through SW3. The settings currently are
thus, with bits numbered according to the markings on the switch banks
and 1=on, 0=off:

             12345678 <--bit numbers
        SW1 11110110
        SW2 11000010
        SW3 10110110

There is a good deal of "small" logic, CMOS and TTL in the cases I've
bothered to look at the numbers on, a bunch of discrete components, and
three socketed "big chips": a 2732 UVEPROM with a sticker on which is
handwritten "1103" and "7.9"; a 74C154 (why this is socketed I have no
idea); and something that looks like a CPU, on which is printed various
things in various ways; I think it's probably an 8031.

There's also a momentary pushbutton switch of no obvious function
(inaccessible with the cover on) labeled SW4 and a six-contact
card-edge connector of equally obscure function.

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Received on Wed May 05 2004 - 02:34:34 BST