Source : Free On-Line Dictionary of Computing

AMD Am2901
     
         A 4-bit {bit-slice} processor from {Advanced Micro
        Devices}.  It featured sixteen 4-bit {registers} and a 4-bit
        {ALU} and operation signals to allow carry/borrow or shift
        operations and such to operate across any number of other
        2901s.  An {address sequencer} (such as the {2910}) could
        provide control signals with the use of custom {microcode} in
        {ROM}.
     
        (1994-11-16)