Encoding (format 13, first word at lower address):
1 | 0 | 1 | 1 | 0 | 1 | 0 | d2 | d1 | d0 | a2 | a1 | a0 | s2 | s1 | s0 |
0 | 0 | 0 | s9 | s8 | s7 | s6 | d5 | d4 | d3 | a5 | a4 | a3 | s5 | s4 | s3 |
Syntax:
STB (-
Rd,
S),
Ra
Constraints:
Outcome:
Notes:
For the avoidance of doubt, the decrement of Ra is carried out before Ra is used to compute the address for loading.
This opcode accesses data memory, and the computed address is therefore a byte address. Accessing a non-existent memory location will trigger a bus error exception.