The LSI chip may contain over 10,000 electronic components on a single chip. As IC technology improved, the medium-scale integrated (MSI) circuit, then the large-scale integrated (LSI) circuit became available. These digital circuits are referred to as small-scale integrated (SSI) circuits. The transistors, resistors, and capacitors are created within or on a single piece of silicon. These small digital circuits might include 10 to 20 transistors along with resistors and capacitors in a package similar in size to that of a single transistor.
These systems were still somewhat bulky and quite expensive and were generally purchased only by larger companies or institutions.īy 1964, the integrated circuit (IC) became commercially available. Toward the latter part of the decade, computers based on the more reliable BJT began to appear. Because vacuum tubes were firmly entrenched as the electronic device of choice, other companies developed computers using this component in the early 1950s. The present bipolar junction transistor (BJT) differs only in geometrical details from the device developed in 1951. The point-contact transistor was invented toward the end of 1947 and the junction transistor in 1951 at Bell Labs. Although reliability was a problem, ENIAC demonstrated the feasibility of the electronic computer. During 1952, for example, approximately 19,000 vacuum tubes had to be replaced to keep the computer functional. The size and power consumption were very large compared to the computers of today, but the worst factor in ENIAC's inefficiency was the unreliable operation of the vacuum tubes making up the digital circuits. This system, called the ENIAC (Electronic Numerical Integrator and Computer), contained over 18,000 vacuum tubes, weighed 30 tons, and occupied a 30- by 50-ft room. While mechanical or electromechanical computers were developed earlier, the first electronic digital computer was constructed at the University of Pennsylvania between 19. Comer, in Encyclopedia of Physical Science and Technology (Third Edition), 2003 I.C History of Digital Electronic Circuits Today's computers are designed with self-checking features that continuously examine the computers for problems.ĭavid J. This experience demonstrated how difficult it was going to be to keep these giant machines running. As a last resort, the replacement panel was checked, and it had exactly the same hardware bug as the original panel-an incredible coincidence. The engineers were bewildered and spent days checking the entire ENIAC top to bottom. The engineers were sure that this bug was the cause of the trouble and replaced the defective panel with the backup panel, but the same problem surfaced again almost immediately. One particular bug was traced to a certain panel of these tubes. Because the vacuum tubes used in the ENIAC were relatively short-lived, backups for every panel of tubes were kept handy. Presper Eckert, Jr., told an interesting story about debugging. (It is interesting to note that many of today's home computers are more than a hundred times faster than the ENIAC, weigh less than 30 pounds, consume about one-thousandth the power, cost about one-thousandth as much, and can store thousands of times as much information.)Īt a recent computer convention, J.
ENIAC could perform 5000 additions or 300 multiplications of 10-digit numbers per second, making it more than a thousand times faster than the Mark I. Binary numbers inside the computers must be converted back and forth to decimal for the convenience of human users.īecause the ENIAC was completely electronic, it performed calculations much faster than the electromechanical computers of the time, such as the Mark I. A binary digit (or bit, as it is called) can be built out of one switch that may be open or closed (off or on). Binary is awkward for humans but convenient for computers. In binary, only the digits zero and one are used, and numbers are carried on every second count. Counting proceeded from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and then to “0 carry the 1” to form the number 10. Every digit in the machine could contain any of the decimal digits from zero to nine. Unlike the ABC and today's binary computers, the ENIAC used decimal arithmetic.
It had 500,000 soldered joints and no moving parts. The machine was completely electronic, consisting of 19,000 vacuum tubes and tens of thousands of other electronic components. It consumed so much electricity that it actually dimmed the lights of the city of Philadelphia (it was kept at the University of Pennsylvania there) when it was turned on.
The ENIAC occupied 1500 square feet of floor space and weighed 30 tons.
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