CPU: I/O configuration

The instruction

     SPxChIn   0,!CPU

will return the board's I/O configuration in U. This will vary with different numbers of XPice expansion boards connected. The items returned are:

U0	Number of digital inputs
U1	Number of digital outputs
U2	Number of analog inputs
U3	Number of analog outputs

Note that, in general, the numbers returned are the maxima for each type of resource. Pins on SPice connectors are configurable to more than one type of I/O. Each such configurable pin will be included in each of the possible of the above counts.

Example:

An SL99 without any expansion boards connected will return the numbers

U0=16	Number of digital inputs
U1=14	Number of digital outputs
U2=5	Number of analog inputs
U3=3	Number of analog outputs

The 14 inputs are 8 external inputs on the base board, 2 option links that appear as inputs and 6 SPice pins that can be configured as inputs.
The 14 outputs are 8 external outputs on the base board plus 6 SPice pins that can be configured as outputs.
The 5 analog inputs are 1 provided on the base board plus 4 SPice pins that can be configured as analog inputs.
The 3 analog outputs are 1 provided on the base board plus 2 SPice pins that can be configured as analog outputs. Of the latter 2, one (Analog output G) is also the thermistor excitation voltage.