AMI S2000 microcontroller family

S2000 is a family of 4-bit microcontrollers manufactured by American Microsystems, Inc (AMI) in the first half 1980. Depending on part number, 2000 or 215x, the microcontroller had either 32 or 40 byte on-chip scratchpad RAM, and 1 KB or 1.5 KB ROM. If desired, ROM memory could be extended to 8 KB by adding external ROM. Instruction set of the MCU included 51 instructions, most of which occupied just one byte. Instruction set was rather simple, and included load and exchange operations, basic arithmetic instructions, I/O and control instructions. There was no conditional branch, but it was possible to simulate one by using conditional Skip instruction (which skipped the next instruction), followed by "Jump" instruction. While the S2000 microcontroller supported subroutines, due to small size of internal stack the subroutines were limited to three levels. The MCU didn't support interrupts.

The AMI S2000 MCUs were packaged into 40-pin plastic or ceramic DIP package. It was possible to order this part in 28-pin plastic and ceramic package - in this case the customer had to specify which optional pins could be removed from the package.