Performs AGU-To-RegisterFile data transfer, i.e. writes data
contained in the AGU accumulator to the high bank of register
Rd via port 4 (P4 in microcode below) according to BS (bank select).
The low part of the register is set to zero if enabled by BS. The
instruction is stack conditioned.
Takes 2 cycles to execute.
Example: ATR0L 0xA4 3
IOC BS4 C4 P4
---------------
AZL 0 0 00
- 3 0 A4
NOT YET
ATROL 0x20 3
!! Writes data contained in AGU
!! accumulator to the high bank
!! of register 0x20 and pads the
!! low bank with zeroes.