TTL Computer logic runs on a 5V power supply. It could run on 3.3V which would work just as well and use less current and power. But the standard remains at 5V. Just as the computer keyboard is setup like a typewriters which was designed to slow typing so the mechanical keys didn't jam!
CMOS Logic runs on a 12V power supply. It is used for battery backup as it uses less current and power. Having two Complementary-MOS Transistors which only use current when switching: Vcc (Voltage-collector-collector, transistor pin) ->
N-type MOSFET -> Signal -> P-type MOSFET -> Gnd (Ground - 0V) instead of the TTL Transistor-Resistor setup that burns heat through the resistor constantly.
12V is also used to drive computer peripherals like your Keyboard, Mouse, Disk-drive, CD-ROM and Modem. High current peripherals like monitors, speakers (but not speaker card) and printers have to have their own separate power supply but share a common Gnd (Ground - 0V) line.
The CMOS voltage range is 3V-15V so you can build a CMOS 40'xx series circuit on plugboard using a PP3 9V Battery. See 'Recommended Electronics Books' above and Tom Duncan's 'Adventures with... electronics / digital electronic / micro-electronics' series. Projects include a Red-Amber-Green traffic light, and 4-bit binary adder.
TTL 74'xx and CMOS 40'xx series chips are separate families but generally can both do the same functions: Logic Gates (NOT, NAND - the most popular on IC's, AND, OR, NOR, EX-OR, and EX-NOR - used by adder circuits), Multivibrators and Clocks, Binary Counters, 4-bit Adders, 3-to-8 Line Multiplexers, 4-bit BCD (Binary Coded Decimal) to 7-segment LED Display Decoders, Shift Registers...
CMOS IC Technology : Complementary Metal-Oxide Semiconductor. Developed in 1963 by Frank Wanlass at Fairchild Semiconductor. Details how Transistor-Transistor Logic works. CMOS 40'xx Series Chips are far less prone to damage from electrostatic discharge (ESD). Link from our friends at the wikipedia On-Line Encylopedia.
CMOS Gates Demonstation info. from Hamburg, Germany. Details how CMOS IC's are designed and fabricated.
TTL IC Technology : Transistor-transistor logic. Also from wikipedia. Each integrated circuit performs separate building-block functions such as:
- Logic gates such as AND, OR, NAND, NOR, XOR, inversion
- Latch elements
- Ripple, synchronous, decade, and hexadecimal counters
- Shift registers
- Timing circuits
- Data bus drivers, buffers, tristate buffers
- Display drivers
- Multifunction logic
- Level converters
- Read-write and read-only memory
- Programmable logic arrays
Posted by Graham on 19 June 2006 on the
- CMOS uses N-type and P-type FETs - actually MOSFETs (hence the "MOS" part of "CMOS"). "NPN" and PNP" are *specifically* used to describe BJTs, which are a whole different device.
- Also, the "less power" part is a fundamental feature of FETs. Gate current on a FET is basically zero in steady-state - it needs a static charge on there, but it only needs current to change state (ie. when the static charge has to be built up or drawn away). This is different from a BJT, which requires a constant gate current to keep the transistor turned on.
- It has nothing at all to do with the push/pull mechanism on the outputs. If you think about it, whatever system you used, you could only have one on at a time anyway - if you tried turning both on at the same time then you'd short-circuit the power lines!
- The advantage of a push-pull output is that you can push current out faster. If you have a transistor to 0V then you can turn off fast (lots of current sink), but the 10K resistor to +V limits you to charging up slowly (and remember that the "slowness" of gates to respond is basically due to internal capacitance). A second transistor to +V lets you zap current into your downstream gates faster.
- You've said yourself why they can't make chips this way - "works in singular instances". You can't get any fan-out from this, so the number of stages you can chain together is limited by your choice of resistor on the very first gate. After a few dozen gates, you're talking tiny values of resistance, and correspondingly large currents, at which point it's game over.
From single Transistors to VSLI (> 1,000,000 Transistors on one chip) and beyond ; plus Intel processors
- William Shockley, John Bardeen and Walter Brattain built the first "practical point-contact" transistor at Bell Labs in 1947. Which lead Shockley to invent the junction transistor in 1951 which he patented. He won a Nobel Prize for his work in 1956.
- The first integrated circuits were manufactured independently by two scientists:
The integrated circuit was actually first conceived by a radar scientist, Geoffrey W.A. Dummer (born 1909), working for the Royal Radar Establishment of the British Ministry of Defence, and published in Washington, D.C. in 1952. Dummer unsuccessfully attempted to build such a circuit in 1956. Interesting article about
Integrated Circuit from Wikipedia - the free on-line encyclopaedia.
- Jack Kilby of Texas Instruments filed a patent for a "Solid Circuit" made of germanium in 1959.
- Robert Noyce of Fairchild Semiconductor was awarded a patent for a more complex "unitary circuit" made of Silicon in 1961.
- The march of Chip technology:
- SSI: Small Scale Integration - 10's of transistors on one chip.
- MSI: Medium Scale Integration - 100's of transistors on one chip - late '60's. Driven by demand from the Minuteman missile and Apollo program projects.
"These programs purchased almost all of the available integrated circuits from 1960 through 1963, and almost alone provided the demand that funded the production improvements to get the production costs from $1000/circuit (in 1960 dollars) to merely $25/circuit (in 1963 dollars)."
- LSI: Large Scale Integration - 10,000's of transistors on one chip - mid '70's.
- VLSI: Very Large scale Integration - 100,000's-1,000,000's of transistors on one chip - '80's - lead to single chip Microprocessors and 1 Mega-Byte RAM chips.
IC's are used by RAM (Random Access Memory - Read/Write - either dynamic memory constantly renewed by the processor every few micro-seconds or static backed-up by a battery but more expensive) or ROM (Read Only Memory) which was used to store the operating system on Microcomputers like the Commodore 64 or BBC Micro. Now the computer Boot-straps (lifting yourself up by!) and loads almost all operating system data from the harddisk drive.
The 6800 microprocessor was developed by Motorola to guide Cruise Missiles. Released shortly after the Intel 8080 in 1975. It had 78 instructions, and came in a 40 Pin DIL (Dual-in-Line) Package. The famous Commodore 64 BASIC and Games Home Microcomputer used it, and a TV as a monitor.
- ULSI: Ultra-Large Scale Integration - > 1,000,000 transistors on one chip.
- WSI: whole uncut wafers containing entire computers (processors as well as memory). "Attempts to take this step commercially in the 1980s (e.g. by Gene Amdahl) failed, mostly because of defect-free manufacturability problems, and it does not now seem to be a high priority for industry."
- SOC: System-on-Chip design. "In this approach, components traditionally manufactured as separate chips to be wired together on a printed circuit board are designed to occupy a single chip that contains memory, microprocessor(s), peripheral interfaces, Input/Output logic control, data converters, and other components, together composing the whole electronic system."
- Another development: Programmable integrated circuits - '80's - reducing the need for many "glue" logic chips. "These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a single chip to be programmed to implement different LSI-type functions such as logic gates, adders, and registers."
- Chips have so many transistors on them now that they dissipate large amounts of heat which can no longer be removed by heatsinks and fans. Another problem is as IC power and communication lines get every simpler capacitances and resistances increase between them. I think they are now at 100 or 70 Nano-meters, one millionth of a milli-metre?
What is the theoretical limit? Isn't it about 100 atoms width at the moment?
- Obiwan posts to EPE ChatZone on Thursday, 15 June: "Current leading edge IC production is using 60 nM, next generation is supposed to be 45 nM. Dread to think what the yields are like. Current density is now at the level that was used for accelerated life tests (burn-in) 25 years ago... which is why modern ICs actually wear out due to metal migration & other joys." Production techniques include Lithographic and X-Ray.
- Zeitghoust posts on Friday, 16 June, 2006: " Don't know what the theoretical limit is, and I suspect that no one else does either. It's all supposed to grind to a halt in 2017 apparently. Gate oxide is about 10nM thick at the moment apparently, I read recently. A million transistors is a smallish chip these days... a little different from the enormous transistor count of the 4004 of immortal memory."
- The 4040 was built by Intel in 1971, and was designed to drive a calculator, but also used to replace collecting of logic gates. It could support 4 KB memory access from the 4-bit address bus if all 16 ROMs were installed. Off course also using it's 12-bit program address. It came in a 16-pin package, and was built of 2,300 transistors, and was followed the next year by the first ever 8-bit microprocessor, the 3,300 transistor 8008 (and the 4040, a revised 4004).
- I understand Russia make the low transistor count chips as they're IC fabrication plants were less advanced (lower transistor count) than the Wests. Who barred transfer of advanced technology to the Communist Block. Eric Honiker the Leader of East Germany was more concerned that his engineers had just invented a better RAM chip than the fall of the Berlin Wall!
Their RAM chip was rendered obsolete when Western technology arrived, or should I say Eastern? I understand the Japanese cornered the RAM market, like they cornered many other markets. Not much margin in it now a days though.
- Intel still rule the microprocessor market. It was said of the price of IBM PC's: 1/3 went to Intel, 1/3 to Microsoft's Operating System[s], leaving only a 1/3 for everything else: monitor, keyboard, RAM, motherboard (minus processor), disk drive... !!!!
- So the new Dual-core Intel Processor uses two separate processors replacing the Pentium 4 (80'986 series) Intel Processor (first one 4-bit 40'40 used by calculators), dividing the work between them, meaning more heat can be dissipated. I can't see how programmers are going to use two processors in parallel efficiently (like Transputer networks only useful for large scale projects like predicting the whether, atomic bio-chemistry, or making CGI: Computer Generated Imagery with movement, light-ray projection and shadows). Also old programmes may not run correctly like MS-DOS (Microsoft Disk Operating System) programmes under Windows XP (you need a special DOS-Box programme to run them).