[rescue] Interface info for IBM Dials and Buttons boxes?

[Julius Sridhar]

On Thu, 21 Feb 2002, Corda Albert J DLVA wrote:

> I just finished tracing the interface out, and I believe I can say
> with certainty that it's capable of RS232.  The units I came
> across have a 9-pin mini-din connector on the back. I was fortunate
> to get a matching adaptor cable that mates this to a rather funky
> DB25 connector, which has a piggyback 9-pin molex on the back of it.
> this mates to another cable (to provide power) which has a Din-6
> connector (Together, both units need 5Vdc at about 1A.  Use a good
> regulated power brick, since there is no on-board regulation,
> and minimal filtration.)
>
> I traced out the wiring, and pins 2 and 3 of the DB25 go to the
> appropriate I/O pins on the Max232 chip. DCD, CTS, and DSR are
> tied high via 2k resistors, so they apparently don't use any
> sort of hardware handshake.
>
> One oddity.  Pin 22 of the DB25 is tied _directly_ to the five
> volt supply.  My guess is that these critters support more than
> one machine (via more than one adaptor cable). I suspect that
> they could probably plug into a "special" mini-din port on the
> back of an RS6000 which may have supplied power along with data,
> or they could be used with other IBM systems via the RS232 cable
> and a power brick adaptor.

The RS/6000 does indeed have a 9-pin tablet connector.  The way you hook
these up is:

RS/6000 Tablet Port --> Spaceball --> Dials --> Buttons --> Tablet.

The tablet must be on the end, because it doesn't have a daisy-chain port.

Peace...  Sridhar