1971 AD to 1976 AD |
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| With the benefit of hindsight (the one exact science), the advent of the microprocessor appears to have been an obvious development. But this was less than self-evident at the time for a number of reasons, not the least that computers of the day were big, expensive, and a complete pain to use. Although these arguments would appear to support the development of the microprocessor, by some strange quirk of fate they actually managed to work to its disfavor. | ||
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| Due to the fact that computers were so big and expensive, only large institutions could afford them and they were only used for computationally intensive tasks. Thus, following a somewhat circular argument, popular opinion held that only large institutions needed computers in the first place. Similarly, due to the fact that computers were few and far between, only the chosen few had any access to them, which meant that only a handful of people had the faintest clue as to how they worked. | Coupled with the fact that the early computers were difficult to
use in the first place, this engendered the belief that only heroes (and heroines) with
size-16 turbo-charged brains had any chance of being capable of using them at all. Last
but not least, computers of the day required many thousands of transistors and the thrust was toward yet more powerful computers in
terms of raw number-crunching capability, but integrated
circuit technology was in its infancy and it wasn't possible to construct even a few
thousand transistors on a single integrated circuit until the late 1960s. The end result was that the (potential) future of the (hypothetical) microprocessor looked somewhat bleak, but fortunately other forces were afoot. Although computers were somewhat scarce in the 1960s, there was a large and growing market for electronic desktop calculators. In 1970, the Japanese calculator company Busicom approached Intel with a request to design a set of twelve integrated circuits for use in a new calculator. |
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| The task was presented to one Marcian "Ted" Hoff, a man who could foresee a somewhat bleak and never-ending role for himself designing sets of special-purpose integrated circuits for one-of-a-kind tasks. However, during his early ruminations on the project, Hoff realized that rather than design the special-purpose devices requested by Busicom, he could create a single integrated circuit with the attributes of a simple-minded, stripped-down, general-purpose computer processor. | ||
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| The result of Hoff's inspiration was the world's first microprocessor, the 4004, where the '4's were used to indicate that the device had a 4-bit data path. The 4004 was part of a four-chip system which also consisted of a 256-byte ROM, a 32-bit RAM, and a 10-bit shift register. The 4004 itself contained approximately 2,300 transistors and could execute 60,000 operations per second. The advantage (as far as Hoff was concerned) was that by simply changing the external program, the same device could be used for a multitude of future projects. | Knowing how pervasive micro- processors were to become, you
might be tempted to imagine that there was a fanfare of trumpets and Hoff was immediately
acclaimed to be the master of the known universe, but such was not to be the case. The 4004 was so radically different from what Busicom had requested that they didn't immediately recognize its implications (much as if they'd ordered a Chevy Cavalier, which had suddenly transmogrified itself into an Aston Martin), so they politely said that they weren't really interested and could they please have the twelve-chip set they'd originally requested (they did eventually agree to use the fruits of Hoff's labors). |
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| In November 1972, Intel introduced the 8008, which was essentially an 8-bit version of the 4004. The 8008 contained approximately 3,300 transistors and was the first microprocessor to be supported by a high-level language compiler called PL/M. The 8008 was followed by the 4040, which extended the 4004's capabilities by adding logical and compare instructions, and by supporting subroutine nesting using a small internal stack. | ||
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| However, the 4004, 4040, and 8008 were all designed for specific applications, and it was not until April 1974 that Intel presented the first true general-purpose microprocessor, the 8080. This 8-bit device, which contained around 4,500 transistors and could perform 200,000 operations per second, was destined for fame as the central processor of many of the early home computers. | Following the 8080, the microprocessor field exploded with
devices such as the 6800 from Motorola in August 1974, the 6502 from MOS Technology in
1975, and the Z80 from Zilog in 1976 (to name but a few). Unfortunately, documenting all of the different microprocessors would require an entire web site, so we won't even attempt the task here. Instead, we'll create a cunning diversion that will allow us to leap gracefully into the next topic ...... Good grief! Did you see what just flew past your window? See also The first personal computers (PCs). |
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| These notes are abstracted from the book Bebop BYTES Back (An Unconventional Guide to Computers) Copyright Information |
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