In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Peter Van der Zee wrote:

Hi John;

In SX/B, images of the values of the port direction (TRIS) registers are maintained in RAM under SX/B control, and hence they are always accessible.

In assembler this is not so:

For the SX28 and smaller processors, the TRIS registers are internal to the processor, and NOT directly readable, although they are writable. If their states are not predictable at any point in your program, then you will need to keep a copy of them in RAM as SX/B does.

In case of the SX48/52, these TRIS registers ARE directly readable through extended MODE settings, so in that case you need not keep a copy in RAM.

This can all be found in the product documentation of the UBICOM website.

Hope that clears thing up for you.

Cheers,

Peter (pjv)

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