Chapter 5 Flashcards
Define computer system.
A system for computing that includes the computing unit itself and its peripherals.
Explain jacquard machine.
The machine was controlled by a ‘chain of cards’ laced together into a continuous sequence. Holes were punched in each card, with one card corresponding to one row of the design.
When was jacquard machine invented?
1804
Who invented Harvard Mark 1? When?
Howard Aiken
1937
How did Harvard Mark 1 work?
Mark 1 read instructions from paper tape, executed the current instruction using series of switches and then read the next one. A separate tape could contain numbers for input.
What is the instruction architecture?
Is the abstract description of the machine from the programmer’s point of view.
Distinguish between Von Neumann and Harvard architecture.
Von Neumann: - CPU with both ALU and registers
- Control unit with instruction register and program counter
- Memory that stores data and instructions
- I/o hardware such as keyboard, display.
Harvard:
- The same except that it has separate program and data memories.
What happens during FETCH, DECODE and EXECUTE?
During FETCH, program counter updates with address of the current instruction. Instruction at that address is read from memory.
During DECODE, the control unit takes the instruction and outputs control signals that will cause the instruction to be performed.
During EXECUTE, the functional units execute the instruction.
Explain the basic meaning of the following:
lli
lhi
lw
sw
bz
bnz
bltz
jalr
lli - loads value into register
lhi - loads value into 8 most significant bits of register
lw - loads data at memory address
sw - store data in register to memory address
bz - branch by offset if register value is equal to 0
bnz - branch by offset if register value is not equal to 0
bltz - branch by offset if register value is less than zero.
jalr - set value of program counter to address register 2 + register 3 and save the old value of program counter to register 1
What is the opposite of lw?
sw
What is the memory address space?
The range of all possible memory addresses accessible to the program is called memory address space.
What is the memory address space of 16-bit processor?
2^16 = 65536 from 0x0000 to 0xFFFF
What are memory mapped registers?
Certain memory addresses reserved for interactions with peripheral devices are called “memory mapped registers”. Writing or reading from said addresses causes the corresponding device to perform some action.
Why is a tri-state inverter necessary?
Multiple High outputs near each other leads to melting.
Explain tri-state inverter gate.
When ENABLE input is “0”, the outer pair of CMOS transistors disconnects OUT from power and ground connections irrespective of the value of IN. Multiple High-Z outputs can be connected together, but only one of them can be enabled at a time.
Distinguish between high speed, local and peripheral buses.
High speed: Connects to CPU, wide operating at high clock frequency.
Local: Connects CPU to adapters (smaller chips outside motherboard). Tend to be serial.
Peripheral: USB, HDMI etc. Tend to be serial.
What are adapters?
Electronic circuits that provide CPU with memory mapped registers for controlling peripheral devices.
What does LPC, AHB , APB and EBI stand for?
Low Pin Count bus
Advanced High performance Bus
Advanced Peripheral Bus
External Bus Interface
What is serial communication?
Is the process of sending data one bit at a time across some communication channel.
What does SPI stand for? Who invented it? When?
Serial Peripheral Interface
Motorola. 1980s.
Explain SPI.
One master, multiple slaves.
SCLK is clock output from master
MOSI is data output from master
MISO is data output from slave
SS decides which slave the master outputs to.
Which bit is shifted first?
Most significant bit.
Give advantages and disadvantages of SPI.
Advantages:
- very simple hardware
- not limited to 8 bits
- uses only 4 pins
Disadvantages:
- speed is limited to just a few MHz
- no way for the slave to pause master transmission
- Other comparable serial interfaces require 3, 2, or even 1 pin.
Give a use of RS-232.
CCTV
What is the baud rate?
Number of symbols to be transmitted through the communication channel per second
Explain RS-232.
A symbol is a voltage reading which can either be high or low.
Transmitting an 8 bit character we first transmit start symbol 0 than transmit 8 bits of data than transmit stop symbol 1
What are the advantages of RS-232?
Character based.
Uses only 3 wires for bi-directional communication or just 2 wires for uni-directional communication.
Does not have a separate clock wire.
What does LVDS stand for?
Low Voltage Differential Signalling.
How is clock information embedded into transmitted signal by LVDS?
- Inserting start-bit and stop-bit to guarantee bit transitions at regular intervals to mimic a clock signal.
- Encoding transmitted data using 8b/10b encoding.
Advantages and disadvantages of LVDS.
A: - lower electromagnetic emissions due to coupling of wires
- lower susceptibility to electromagnetic interference
- lower noise
- lower power consumption
D:
- requires carefully designed cables
- special transmitter and receiver circuits
How does LVDS work in one word?
Magnetism
Give main use for SPI, RS-232 and LVDS.
SPI - like temperature sensors or SD cards
RS-232 - connecting to computer consoles in Linux based embedded devices
LVDS - SATA and PCIe (differential signalling)
What does RS in RS-232 stand for?
What does SATA stand for?
What does PCI stand for?
Recommended Standard
Serial Advanced Technology Attachment
Peripheral Component Interconnect
