V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

SCMP
       Stream Control Message Protocol (ST2)


The Free On-line Dictionary of Computing (30 December 2018):

SC/MP

    (Nicknamed "Scamp") A typical 8-bit
   microprocessor from National Semiconductor released in
   April 1976.  It was intended for control applications (a
   simple BASIC in a 2.5K ROM was added to one version).  It
   featured 16 bit addressing, with 12 address lines and 4 lines
   borrowed from the data bus (it was common to borrow lines from
   the data bus for addressing).  Internally, it included three
   index registers (P1 to P3) and two 8-bit general-purpose
   registers.  It had a PC, but no stack pointer or
   subroutine instructions (though they could be emulated with
   index registers).  During interrupts, the PC was saved in
   P3.  It was meant for embedded control, and these features
   were omitted for cost reasons.  It was also bit serial
   internally to keep it cheap.

   The unique feature was the ability to completely share a
   system bus with other processors.  Most processors of the time
   assumed they were the only ones accessing memory or I/O
   devices.  Multiple SC/MPs could be hooked up to the bus, as
   well as other intelligent devices, such as DMA controllers.
   A control line (ENOUT (Enable Out) to ENIN) could be chained
   along the processors to allow cooperative processing.  This
   was very advanced for the time, compared to other CPUs.

   In addition to I/O ports like the Intel 8080, the SC/MP also
   had instructions and one pin for serial input and one for
   output.

   (1994-11-16)