TMP47C101/201
2. Internal CPU Function
2.1 Program Counter (PC)
The program counter is a 11-bit binary counter which indicates
the address of the program memory storing the next instruc-
tion to be executed.Normally, the PC is incremented by the
number of bytes of the instruction every time it is fetched.
When a branch instruction or a subroutine instruction has been
executed or an interrupt has been accepted, the specified val-
ues listed in Table 2-1 are set to the PC. The PC is initialized to
“0” during reset.
Figure 2-1. Configuration of Program Counter
The PC can directly address a 2048-byte address space.
However, with the short branch, the following points must be
considered:
• Short branch instruction [BSS a]
In [BSS a] instruction execution, when the branch con-
dition is satisfied, the value specified in the instruction
is set to the lower 6 bits of the PC.That is, [BSS a]
becomes the in-page branch instruction. When [BSS
a] is stored at the last address of the page, the upper 5
bits of the PC point the next page, so that branch is
made to the next page.
Table 2-1 Status Change of Program Counter
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