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36 Cards in this Set
- Front
- Back
Why did CMOS transistors relpace TTL logic? |
VLSI chips use CMOS transistors because bipolar transistors always draw some current, while CMOS only draws current when the output state changes |
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Describe DRAM |
Dynamic Random Access Memory can be formed by a transistor and a cap. It has a very high density. The storage is dynamic so it refreshed over time. The cap discharges a refresh cycle would refresh all memories. |
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Describe SRAM |
Static Random Access Memory is a flip flop, it will hold content until rewritten or power off. It is made of 6 transistors so it is larger then DRAM. Used as a scratch pad during program execution. |
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LIFO SRAM |
Used as an address stack to store adresses during a subroutine call, so the program execution can continue once the instruction is returned. The address is pushes, then stacked and popped. |
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CAM SRAM |
Is used to translate page addresses to chip addresses. |
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FIFO SRAM |
Stores instructions in the instruction queue |
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Shift Register SRAM |
sterilize data. |
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EPROM |
it is controlled by a gate and can be used to turn the transistor on or off. During Programming, the charge is increased to logic 1 by using a reference greater then 5V. When erasing the logic is at 0. |
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Flash |
Same as EPROM but is orientated to blocked of 64 bytes at the same time. Larger and much faster. |
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ROM |
Densest memory, for hardcoded program. It consist of a single transistor and is programmed to be 0 or 1 in manufacturing. |
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What is a Configuration word? |
In order to use physical hardware, the configuration word is hardwired during program and it assist with communication. It well tell you what oscillator is being used, how to power reset and how to enable and disable characteristics. This is found in the program memory |
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What are the 2 types of oscillators? |
Crystal: this is the most accurate, uses two caps to stabilize the frequency. Resistor/Cap: the cheaper less accurate alternative, frequency depends on the resistance and capacitance, the operating temp and the voltage. Only used for low performance applications. |
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Describe the reset sequence when a reset pulse occurs |
*The internal memory and peripherals might reset. Starts a set sequence 1. load the configuration word 2. set the parameters according to the word 3. fetches the first instruction |
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What is the Difference between Hard and soft restart? |
A hard or external reset: initiates the reset sequence. This is ideal for development to reset the processor A soft reset cause the program counter to reset to the first instruction but does not change the hardware configuration. |
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What impact does standby and system voltage have on low application? |
low applications have a sleep mode to save battery life. by decreasing the system clock to 0. Only the essentials are needed to wake the micro controller. |
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What is the key of in-circuit programming? |
it allows the micro controller to be reprogrammed while still installed in the circuit. |
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What is an embedded controller parallel port? |
They are a 1 byte port and they can be selected as input or output |
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What is Tri-state logic? |
Tri state buffering allows for a third state. A high impedance state that allows multiple devices to to use a common bus. |
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What are the key features of memory mapped I/O |
No special instructions are needed. Memory mapped I/O treat locations as part of the register memory address space. |
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What are the main parts of the micro controller |
CPU ROM RAM Timers Interrupt I/O ports Analog Digital converters Digital Analog converters Serial Interfacing ports |
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Describe VLSI |
Functional: represents how the chip functions which are defined and verified by simulation Logic: individual modules are implemented at the gate level by simulation Physical: consist of a design and verification of detailed boolean descriptions |
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How is VHDL used for the design process? |
It is used for the design process as a low estimation at the system specs level. it means complete redesign if there is not enough actual surface area at the physical level. |
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What are the differences between the 2 main ISA? |
CISC: reduced number of instructions per program many instructions are preforming multiple operations hardware has to handle large instruction set RISC: reduce ISA provides minimal and simple same length instructions reduces hardware complexity, increase software complexity |
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What was the driving force for micro-controllers |
increase density DRAMs. double's in density every 18 months |
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How did SSI transition to VLSI? |
SSI started with individual gates I/O interfaces were then standardized to help third parties develop interfaces. MSI was introduced in the form of octal latches which reduces SSI gates. this allowed gates to be implemented. The next progression was electronic calculators. Intel 1101 was invented in the late 70s |
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What are the buses |
Bus: electronic highway that allows data to move between devices Address: Allows the CPU or DMA to address memory and peripherals Data: allows data to move between devieces Control: controlled the address and data bus |
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What do early chips require to operate? |
They required multiple chips because there were minimal gates per chip. |
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What are the key features of CISC |
Complex instructions Variable length instruction Complexity in the microcode program size is smaller many addressing modes less memory needed |
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RISC |
Many general purpose registers Complexity is in the compiler simple same size instructions optimizing the pipeline requires more instructions |
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What does intellectual property play in VLSI design |
Licensing and royalties on the designs pevent customers from adopting ideas for their products. |
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What are the tradeoffs design engineers make when making controllers? |
Maximize performance given the constraints of existing technologies and market. best design is when memory,hardware and software is balanced. |
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Describe the factors in measuring design performance for embedded controllers? Which factor has the most impact on performance? |
Processor or silicon tech ISA or hardware optimizations few instructions increase performance (75% processing time and 10% of instructions) |
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What is locality? Why is locality important for microprocessor design? |
A program executes a sequence of instruction and then branches A program processes a sequential data set Even though memory has increased at the same rate as processors, DRAM is still 10 times slower then processors |
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What impact does the memory speed pyramid (register, cache, memory, file storage) have on microprocessors? |
They maximize the fetching of programs and fetching and storing of data |
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How does cache work? |
When the processor request an address, the cache determines if its in the cache. If it's a HIT then the cache supplies a program and the processor runs at full speed If it's a MISS then the cache will fetch it from slower memory, idles the processor until it arrives. Locality makes the cache get the next few addresses instructions |
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What is pipelining? What is the problem with pipelining when a branch instruction is executed? |
Pipelining: logic is due to functionality. This means fetch, decode, execute sequence is paralleled. (instructions are sequential) It is only when a branch is executed that the pipeline is incorrect and the processor will lose a cycle. |