Lecture 2 Flashcards
Word size
Number of bits processed by a computer’s CPU in one go
Function of ALU
Performs Logic calculation
PC
Tells the CPU where to get the next instruction and When to execute
MAR
Memory address register - holds the address of the current instructions that is fetch from memory or holds the address in memory to which data is to be transfered to
MBR
Memory buffer register- holds the contents Found at the address held in the MAR or data is being transfered to the primary memory
CPU register
Used to store useful info(instructions and data)
ID
Instruction decoder- tells the ALU What to do with the data
CPU basic operation
To fetch instructions from the program memory (location of instruction which the pc determines)
Determine what to do with that data next [decoded]. This is performed by the ID
Consist of a single or sequence of actions and various parts of the CPU are electrically connected so that they can perform the desired operation. [executed]
Memory basic concept
If want to access a data, you need to know the address of the data so that it can extracted.
Byte is the smallest addressable But in I/O registers, to address individual bits can occur
5 memory types
RAM,ROM, EPROM (can be programmable but can be errased by UV light, EEPROM (can be programmable but can be erased using electical), FLASH (like EEPROM But can only erased in blocks)
Stack
a part of RAM that used to hold arguments and automatic variables
- reminding the order in which a function is called so that it can be returned correctly
- store address of the PC Especially used in interrupt
WREG
- used for all arithmetic and Logic intructions
- store ALU output result
- connected go the ALU
- one data can put in WREG and one in memory
STATUS
-contains arithmetic status of the ALU, reset status, and bank select bit for data memory, store special condition flags of the ALU Operation, store carry in calculation
