Section One: Before the Great Dark Cloud.
             ---------------------------
Part I: The Intel 4004 (1972)

    The first single chip CPU was the Intel 4004, a 4-bit processor meant for
a calculator. It processed data in 4 bits, but its instructions were
8 bits long. Internally, it featured four 12 bit(?) registers which acted as
an internal evaluation stack. The Stack Pointer pointed to one of these
registers, not a memory location (only CALL and RET instructions operated on
the Stack Pointer). There were also sixteen 4-bit (or eight 8-bit) general
purpose registers
    The 4004 had 46 instructions. Intel created an 8-bit version of this, the
8008 (intended for a terminal controller).
[for additional information, see Appendix B]

Part II: The Intel 4040 and 8080

    The 4040 was compatible with the 4004 instruction set - the 4040 had 60
instructions, which included the 46 4004 instructions. The 8080 was similar to
the 4040, except being 8 bits wide.
    The 8080 had a 16 bit address bus, and an 8 bit data bus. Internally it
had seven 8 bit registers (six which could also be combined as three 16 bit
registers), a 16 bit stack pointer (the stack was stored in memory, not in an
internal register set), and 16 bit program counter. It also had several I/O
ports - 256 of them, so I/O devices could be hooked up without taking away or
interfering with the addressing space.

Appearing in IEEE Computer 1972:
-------------------------------

NEW
PRODUCTS

FEATURE PRODUCT

COMPUTER ON A CHIP

   Intel  has  introduced  an  integrated  CPU  complete with
a 4-bit parallel adder, sixteen 4-bit registers, an accumula-
tor  and  a  push-down  stack  on  one  chip.  It's  one of a
family  of  four  new  ICs  which  comprise  the  MCS-4 micro
computer  system--the  first  system  to  bring the power and
flexibility  of  a  dedicated general-purpose computer at low
cost in as few as two dual in-line packages.
    MSC-4   systems   provide  complete  computing  and  con-
trol  functions  for  test  systems,  data terminals, billing
machines,   measuring   systems,   numeric   control  systems
and process control systems.
    The  heart  of  any  MSC-4  system  is  a  Type 4004 CPU,
which  incudes  a  set  of  45  instructions.  Adding  one or
more   Type   4001   ROMs   for   program  storage  and  data
tables   gives  a  fully  functioning  micro-programmed  com-
puter.   Add   Type  4002  RAMs  for  read-write  memory  and
Type 4003 registers to expand the output ports.
   Using  no  curcuitry  other  than  ICs from this family of
four,  a  system  with  4096  8-bit  bytes of ROM storage and
5120   bits   of  RAM  storage  can  be  created.  For  rapid
turn-around  or  only  a  few  systems,  Intel's erasable and
re-programmable   ROM,   Type   1701,   may   be  substituted
for the Type 4001 mask-programmed ROM.
    MCS-4   systems  interface  easily  with  switches,  key-
boards,  displays,  teletypewriters,  printers,  readers, A-D
converters   and  other  popular  peripherals.   For  further
information,  circle the reader service card 87 or call Intel
at (408) 246-7501.
              Circle 87 on Reader Service Card

            COMPUTER/JANUARY/FEBRUARY 1971/71
