Lecture 1 - Introduction Flashcards
Define digital
DIGITAL comes from digit - “integer numbers” instead of “floating point
Digital vs Analog
Analog:
– Susceptible to noise
– Deterioration through playing
– Scratches
+ High-end systems can have higher frequency range
Digital
+ Higher signal-to-noise ratio
+ Contact-less reading (laser)
+ Error correction coding
– Digitizing process loses some original info
What are switches and what are the 6 types?
All digital systems rely on switching between two logic states: 0 and 1 (binary numbers)
* There have been many development stages in switching systems, not all of them electronic
1. Mechanical
2. Electromagnetic: Relay
3. Electronic: Vacuum Tube
4. Electronic: Transistor
5. Gates and Integrated Circuits
6. Microprocessors
What are mechanical switches and what are the common problems?
Before Electricity was discovered, there was Mechanics
* Complicated machinery was invented and built without electronics, just using mechanical parts
Problems with mechanical switches:
* Reliability
* Wear&Tear Þ Short lifetime
* Relatively large size
* Too slow
What are electromagnetic swtitches, replays and the problem with electromagnetic switches?
- All electronics, all computers and all IT are based on automatic switching
- First automatic switching devices were Relays (electromagnetics)
- Now we can switch with power, e.g. a signal coming from another circuit
Problems with electromagnetic switches: better than mechanical switches, but still
* Reliability
* Wear&Tear Þ Short lifetime
* Relatively large size
* Too slow
What is a vacuum tube?
- Triode as electronic switching device or amplifier
- Faster and more reliable than relays
- Still reliability and lifetime issues
What is a transistor?
- Semiconductor device
- Switch or Amplifier
What are Logic gates?
- There are 3 types of logic gates ‘and’, ‘or’ and ‘not’
- Logic functions AND, OR, NOT form a basis for all Boolean operations
- Using logic gates allows to build digital electronic systems of higher complexity
- Logic gates are implemented using transistors
- Logic gates are the first step to integrate several transistors on a single chip
-NOTE LOGIC CHAINS AS WELL
What are gates and diodes (aka transistor equivalents)?
There are 2 ‘nand’ and ‘nor’
What is a microprocessor?
A microprocessor is a highly integrated general purpose digital circuitry with several inputs and outputs. Its functionality can be changed by software that resides in memory.
Why use a microprocessor (adv) instead of discrete logic?
Advantages of using microprocessors:
* Fewer chips required , therefore
– Cheaper
– Smaller
* More flexible (easier to change design)
* Easier to design and implement
What are microprocessors considered to be?
- ## Microprocessors are the heart of every PC or workstation and of many, many electrical devicesEmbedded Systems.
- We distinguish:
– Microprocessor (CPU, central processing unit)
– Microcontroller (CPU + timers/counters + on-board memory, etc.) - Processing power (and price) of microprocessors vary and must be selected to match the application.
- The majority of electrical devices, from watches over TVs, remote controls, washing machines, all contain microprocessors (see examples).
What is Moore’s Law?
- Faster chips and more components in every chip generation?
- In fact, doubling the number of components and speed every 1.5 years, known as Moore’s Law
- How is this possible: Every other technical system has only a few percent improvement per year.
- The trick is not due to any design improvements, but merely miniaturization !
- Building smaller components allows more components on the same area (e.g. 4 * RAM size) and will reduce signal runtime (shorter distances) and therefore increase clockspeed (e.g. double) at virtually same production cost.
When will Moore’s Law end/fail?
- Once the atomic level (or maybe quantum level) has been reached, no further size reduction will be possible
- The market has already reacted to this by putting multi-core parallel processors onto the market
- However, this trend has other limitations, as ~10 cores are the limit for shared memory bus architectures
- Distributed systems on a chip limited by chip size
What is embedded systems?
A combination of hardware and software which together form a component of a larger machine.
