MIT PDP-10 'Info' file converted to Hypertext 'html' format by Henry Baker

Boolean Logic

There are 16 possible boolean functions of 2 variables. The PDP-10 has 16 instruction classes (each with 4 modifiers) that perform these operations. Each boolean function operates on the 36 bits of AC and memory as individual bits.

C(AC)   0       0       1       1
C(E)    0       1       0       1

SETZ    0       0       0       0       SET to Zero
AND     0       0       0       1       AND
ANDCM   0       0       1       0       AND with Complement of Memory
SETA    0       0       1       1       SET to AC
ANDCA   0       1       0       0       AND with Complement of AC
SETM    0       1       0       1       SET to Memory
XOR     0       1       1       0       eXclusive OR
IOR     0       1       1       1       Inclusive OR
ANDCB   1       0       0       0       AND with Complements of Both
EQV     1       0       0       1       EQuiValence
SETCM   1       0       1       0       SET to Complement of Memory
ORCM    1       0       1       1       OR with Complement of Memory
SETCA   1       1       0       0       SET to Complement of AC
ORCA    1       1       0       1       OR with Complement of AC
ORCB    1       1       1       0       OR with Complements of Both
SETO    1       1       1       1       SET to One

Each of the 16 instructions above have four modifiers that specify where to store the result. No modifier means result to AC. Modifier I means Immediate: the memory data is <0,,E> and the result goes to AC. M as a modifier means result should be stored in memory. B means store the results in both memory and AC.