The PDP/8E from 1970 had an optional module to implement some additional microcode that included the instructions:
7501 - MQA or Multiplier Quotient with Accumulator
7421 - MQL Multiplier Quotient Load
Note that these were microcode rather than silicon on chip. As described in Group Three Microcoded Instructions :
On all models of PDP-8 prior to the PDP-8/E, the group three instructions were only implemented if the EAE option was present. If this option is absent on such machines, all group three instructions become no-ops.
On the PDP-8/E and following models, CLA, MQA and MQL instructions are implemented in the standard CPU, while the other operations are implemented in the optional EAE. Portable code should avoid relying on the availability of any of these instructions.
The CODE field and the SCA bit only function if the EAE is present; these should be zero unless specific EAE instructions are intended. These are documented elsewhere.
Note that warning that this wasn't for portable code. And while I don't have the actual specs in front of me, they appear to be little itty bitty hard coded programs running in cache than actual instructions.
The IMP-16 from 1973 had a multiply instruction as documented in section 7.4.3 of IMP-16 Programming and Assembler Manual
7.4.3 Multiply (MPY) - Extended Instruction Set
The multiply instruction automatically uses the first (AC0) and second (AC1) working registers. It is the programmers responsibility to store data from these registers before coding a multiply instruction.
The unsigned integer is the second working register (AC1) is multiplied by the positive integer in the effective address. The high-order part of the 32-bit result is stored in AC0 and the low-order part is stored in AC-1.
