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Memory Access via Address in ACCU 1
SA Register:
SAC = STEP Address
Counter
BA Register:
Block Start Address
BR Register:
Available Base Address
Register
Example of TDI in the byte
area
9 - 18
On completion of the operation, the 20-bit absolute address of the
operation to be processed next is entered in the SA register.
During program processing of the STEP 5 user program, a 20-bit
absolute address is entered in the BA register. This address is in the
higher order block (corresponds to the return address). It is the address
of the operation to be processed next.
The base address register (20 bits) allows you to calculate addresses
and to execute indirect load and transfer operations without using the
ACCUs for the address. It can be used freely during STEP 5 program
processing.
:L
DH 1234 5678
:L
DH 000E FC00
:
:TDI A2
E FC00 = 34
(The values '12H' and '56H' from
E FC01 = 78
ACCU 2 are lost)
Load data
Load address of flag
byte FY 0
Store content of ACCU 2
CPU 948 Programming Guide
C79000-G8576-C848-04
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