was all included internally so a single line on the circuit board was all that was needed to implement this feature. The original idea was to ease the creation of microcontroller-like applications containing an SC/MP, one or more DMA controllers, and a single shared memory. Designed specifically to be as low-cost as possible in terms of an overall system, the desire to lower the cost of the SC/MP itself also led to decisions about the bit-serial ALU and the inclusion of serial input/output lines to eliminate the need for a separate UART (this feature was removed in the later SC/MP III). SC/MP unusual features SC/MP increments the program counter before fetching the instruction, so that on reset it actually starts executing instructions from location 0001. This also needs to be taken into account for calculating displacements, since the offset will be added to the program counter which will be still pointing to the location of the displacement and not the next instruction. Implementations ISP-8A/500 SC/MP-1 Clocked at 1 MHz, first implementation (P Channel MOS technology) INS 8060 ISP-8A/600 SC/MP-2 Clocked at 4 MHz (internally 2 MHz) first N Channel MOS version (single +5V supply) INS 807x SC/MP-3 Clocked at 4 MHz (internally 2 MHz) included variations with up to 4 KB ROM (optional onboard BASIC (NIBL)) Uses The SC/MP was also used as the basis of a single board microcontroller produced by Science of Cambridge (later Sinclair Research Ltd) called the MK14. Montgomery Elevator Co of Moline IL (later purchased by KONE, Inc) used the SC/MP as the basis for its first micro processor based elevator controller released in 1975. There are still many of these units running in buildings across the U.S.A. Notes References More info and emulators National Semiconductor datasheet Information about the SC/MP including an emulator MK14 original manual – including ISA description A SC/MP II Single Board MCU with NIBL BASIC in ROM NSC 807X datasheet SC/MP Development System at the Centre for Computing History Various INS807x Series PDF files Hand-wired INS8073 single-board computer with info on assembly of source code SC/MP 8-bit microprocessors