Message format

Each message comprises an instruction followed by one or more byte operands. The instruction is always sent by the external programmer. Depending on the instruction all the following operands are sent either by the external programmer or by the TPI.

The messages can be categorized in two types based on the instruction, as follows:

All the instructions except the SKEY instruction require the instruction to be followed by one byte operand. The SKEY instruction requires 8 byte operands. For more information, see the TPI instruction set.