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

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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


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