IBM 2030 Manual Of Instruction page 209

register data is used as the B source
for ALU. The data is then:
A source
B source+
0000 xxxx x are the
program
mask tits
0010 0000
R-register set 0010 xxxx
The four high bits 0010 when returned
to core signify that our resultant
answer was greater than zero. Notice
the table in Figure 3-26.
3-35