14 Questions
How many different addresses can the 16-bit address bus specify?
65,536
What is the primary function of the address decoder?
To ensure only one IC is active at a time
What type of data is stored in ROM?
Initialization instructions and subroutines
What happens to the contents of RAM when power is turned off?
It is lost
What is the purpose of the control bus?
To carry control signals for the ICs
What is the width of the data bus?
8 bits
What provides data to the microprocessor?
Input port
What is the purpose of the monitor program?
To initialize the microprocessor
What is the primary purpose of an output port?
To provide a way for the microprocessor to talk to the outside world
What triggers the D flip-flop to latch onto the data on the data bus?
A clock trigger pulse from the control bus
What is the role of the address decoder in the output port?
To issue a pulse on the write line to the control bus
What is the function of the octal D flip-flop in the output port?
To latch onto data from the data bus and drive the LEDs
What is the purpose of the input port in this system?
To receive data from an input device and dump it to the data bus
What is the sequence of events to load the D flip-flop?
The microprocessor sets up the data bus, then the address, and finally the clock trigger pulse
Study Notes
Address Bus
- The address bus is 16 bits wide, allowing it to specify 65,536 different addresses.
- The low-order bits on the address bus select a particular location within a selected memory IC.
- The address bus is used by the microprocessor to select a particular location or IC to be active.
Data Bus
- The data bus is bidirectional, allowing the microprocessor to send or receive 8 bits of data to or from a selected address.
- The data bus is used for data transfer between the microprocessor and memory or I/O devices.
Control Bus
- The control bus carries control signals that are tapped into by other ICs to determine the type of operation being performed.
- The control signals indicate whether the operation is a read, write, I/O, memory access, or other operation.
Address Decoder
- The address decoder is usually an octal decoder that ensures only one IC is active at a time to avoid bus conflicts.
- The address decoder receives information from the microprocessor via the control and address buses to determine which IC to activate.
Memory
- ROM (Read-Only Memory) contains initialization instructions and subroutines that can be called by the microprocessor.
- The monitor program or operating system is stored in ROM and is permanently stored.
- RAM (Random Access Memory) is volatile, meaning it loses its contents when power is turned off, and is used for temporary data storage.
Input Port
- The input port provides data to the microprocessor via the data bus.
- It is an octal buffer with three-stated outputs and receives input from devices like a keyboard or toggle switches.
- The input port dumps its information to the data bus when it receives a chip enable from the address decoder and a read command from the control bus.
Output Port
- The output port provides a way for the microprocessor to talk to the outside world.
- It can send data to output devices like printers or LEDs.
- An octal D flip-flop is used as the interface, and the microprocessor must set up the data bus and address of the output port to load the D flip-flop.
This quiz covers the basics of the address bus in computer organization, including its width, functionality, and address specification.
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