Did You Know?

• The first single chip CPU was the Intel 4004, a 4-bit processor meant for a calculator (not Intel 8086). It processed data in 4 bits, but its instructions were 8 bits long. Program and Data memory were separate, 1K data memory and a 12-bit PC for 4K program memory (in the form of a 4 level stack, used for CALL and RET instructions). There were also sixteen 4-bit (or eight 8-bit) general purpose registers.
  The 4004 had 46 instructions, using only 2,300 transistors in a 16-pin DIP. It ran at a clock rate of 740kHz (eight clock cycles per CPU cycle of 10.8 microseconds) - the original goal was 1MHz, to allow it to compute BCD arithmetic as fast (per digit) as a 1960's era IBM 1620.
  The 4040 (1972) was an enhanced version of the 4004, adding 14 instructions, larger (8 level) stack, 8K program space, and interrupt abilities (including shadows of the first 8 registers). Should Pioneer 10 and Pioneer 11 ever be found by an extraterrestrial species, the 4004 will represent an example of Earth's technology.
• Then came Intel 8086 (1978) - This chip was skipped over for the original PC, but was used in a few later computers that didn't amount to much. It was a true 16-bit processor and talked with its cards via a 16 wire data connection. The chip contained 29,000 transistors and 20 address lines that gave it the ability to talk with up to 1 MB of RAM. What is interesting is that the designers of the time never suspected anyone would ever need more than 1 MB of RAM. The chip was available in 5, 6,, 8, and 10 MHz versions.
• Intel was not the only manufacturer playing in the sandbox at the time. AMD put out its AM486 series in answer to Intel's counterpart. AMD released the chip in AM486DX4/75, AM486DX4/100, and AM486DX4/120 versions. It contained on-board cache, power management features, 3-volt operation and SMM mode. This made the chip fitting for mobiles in addition to desktops. The chip found its way into many 486-compatibles.