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9 September 1945 –Ensign Grace Murray Hopper (RADM, USN) removed the first “bug” from a electromagnetic relay in the Harvard Mark II where it had been smashed, halting the computer. She taped the moth to a page the log book.
1958 – Jack Kilby created the first “ integrated circuit ” at Texas Instruments to prove that resistors and capacitors could exist on the same piece of semiconductor material. His circuit consisted of a sliver of poisonous germanium with five components linked by wires. Germanium was soon replaced by silicon (1961).
1971 - Federico Faggin, Ted Hoff, and others at Intel designed the 4004 microprocessor while building a custom chip for Busicom, a Japanese calculator maker. The 4004 had 2,250 transistors, handling data in four-bit chunks, and could perform 60,000 operations per second.
Electronic Hobby Computers evolve into Personal Computers!!
1975 - Electronics hobbyists buy the earliest personal computer
MITS Altair 8800 (Intel 8080)
1976 - Consumer computers arrive after several companies begin large scale manufacturing
COBOL (COmmon Business Oriented Language) for business data processing
FORTRAN (FORmula TRANslator) for scientific and engineering problems
BASIC (Beginner’s All-Purpose Symbolic instruction Code) for educational and personal computing (NOTE: Visual Basic is now widely used in business office automation to build client-server applications and integrate them with office applications)
Pascal for educational and general-purpose (led to Ada, now widely used in government and defense contracts)
C, C++ and Java for cross-platform portable, object oriented (reusable modules) application and game development
Computer pictures are stored as millions of colored dots called “ pixels ” (picture elements) that have to be translated to an analog signal for an analog CRT monitor to display them (LCD panels are already digital so no translation is required).
Each black & white pixel is either on or off; each color pixel is three dots, Red, Green, and Blue (RGB) that combine to create a color. Color pixel combinations range from 256 possible colors to over 16.8 million colors (real, or true color).
The more pixels a picture has, the better it looks (it has a higher resolution). Each pixel has an associated color and location on the screen expressed in binary terms.
When stored, each pixel’s information is saved to disk separately . In a true color (32 bit) pixel, 4 bytes are used to store the color information for each dot in the pixel. For a 1600x1200-pixel display this is 8-million bytes of video memory, stored as one 8mb disk file! (bit-depth in How Computer Monitors Work )
For more detailed information see How Graphics Cards Work
Normal sound is made up of waves or vibrations. Each sound wave has a wavelength (how far between the waves) and amplitude (how high the wave is).
A mixed, analog waveform signal comes in to the sound card from a source (microphone) and is processed in real-time by an analog-to-digital converter (ADC) circuit chip to create a binary (digital) output of 1s and 0s. This is done at a specified interval or “sampling frequency” (i.e., 1/10th of a second).
The digital output from the ADC is further processed and compressed by the digital sound processor (DSP), and the output from the DSP is sent to the computer's CPU via the sound card connections and the data bus on the motherboard.
Digital sound data is processed by the CPU and sent to the hard-disk controller to be recorded on the hard-disk drive as a wav file .
Playback is a reversal of this process, using a a digital-to-analog converter (DAC) circuit chip to play back the binary sound file.
For more detailed information see How Sound Cards Work
Computers communicate if they are electronically connected, have the appropriate software, and have common protocols or rules for negotiating their communication.
Computers are digital, as are networks, but phones and wireless communications move data primarily as analog sound waves.
Modems translate digital information to analog sound for transmission along telephone lines, and back to digital at the other end . They must synchronize speeds, block sizes, and correct errors during communications.
Early modems were 300 baud (bits per second, or about 36 characters per second) 33.6 KBPS modems move over 4000 bytes per second.
Analog telephone lines are generally limited to modem speeds of 33.6 KBPS; new 56K modems and 64K to 128K ISDN connections make use some of the digital aspects of modern telephone lines.
DSL uses high frequency compression to achieve 1.5 mbps down; Cable Modems can deliver 30-40 mbps of _shared_ bandwidth
Many computers make digital connections to a local area network (LAN) or wide area network (WAN) via telephone lines (twisted pair), coaxial cable, fiber optic cables, radio, or wireless communications.
Networks make it possible for large numbers of computers to communicate with each other, and to share resources such as files, applications, and devices .
Networks manage digital traffic by moving data as packets, with elaborate protocols for ordering or prioritizing them, checking errors, and filtering.
Local area networks can be configured as star networks, bus networks, or token-ring networks
Networks can be connected to WANs or to the Internet via modem, ISDN, cable modem, satellite, and other devices
For more detailed information see How Ethernet Works
Email allows users to send and receive electronic messages over any type of network or modem connection using a store and forward methodology .
Messages are uploaded to the local mail server, passed to the recipient’s account on that server, or forwarded to an external mail server over a number of “hops” via intermediate servers.
Messages are downloaded by the recipient’s mail client from their mail server when the messages arrive, or when the recipient opens an active connection to that server from their client.
Depending on the type of mail service, messages may remain on the host mail server or be downloaded to the local computer.
Improved bandwidth for networks and the Internet has made instant messaging and real-time chat a viable form of electronic communication, and is making voice-over-IP practical as well.
For more detailed information see How Email Works
Email Web Mail Server (HotMail, Yahoo, AOL, etc.) POP3 Server (your ISP) IMAP Server (UNT EagleMail) Proprietary data-based Mail Server (Exchange, GroupWise) Email Client (Outlook) Web Browser (IE or Netscape) IMAP Client (Outlook Express) POP3 Client (Netscape, OE) * Proprietary servers usually store email messages and attachments in a real database of some form * POP, IMAP, and some Web Email servers store email messages and text-encoded attachments as text files in most cases * Email moves between servers over SMTP * The user reads their email by using some sort of client software to connect to the mail server SMTP Connections SMTP Connections SMTP Connections SMTP Connections