DMA Direct Memory Access
DMA transfers data directly from the drive to memory w/out involving the CPU.
address bus
A bus is a collection of conducting wires which connect the processor and other devices in parallel scheme. The function of an address bus is to carry the address of the memory locations from the processor to the memory device, the address bus is unidirectional(only in one direction) in this processor so the flow of information on this bus is from the microprocessor to the attached device(memory module).
The address bus is used by the processor in a computer to locate a piece of data from the RAM (Random Access Memory) that it needs to access. No real data is carried via the address bus, as this is the job of the Data Bus. The pieces of data that the address bus locates are called "addresses" and the address bus transfers "data addresses" to and from the control unit.
The address bus is unidirectional(only in one direction) in the processor. So, the flow of information on this bus is from the microprocessor to the attached device(memory module).
You need 20 bits of address bus to address 1 Mb of memory.
With a 20-bit address bus, a computer can address approximately 1,048,576 memory locations, which is equivalent to 1 megabyte of memory.
address bus
The bits of address bus inform the memory(Ram) which particular element is to be read or write in memory.
The Type of transfers that must a computer interconnection structure support thats a bus is the following: (1) Memory to Processor (2) Processor to Memory (3) I/O to Processor (4) Processor to I/O (5) I/O to or from Memory
A memory with a 16 bit address bus can address 216 or 65536 distinct items. If each item is 32 bits in size, then the item is 4 bytes. The size of this memory is then 262144 bytes. (256Kb)
The data bus in the 8086 is 16 bits in size, while the address bus is 20 (16bits would only address 64KB of memory, an extra 4 bits allows to address the total of 1MB, this is done trough segmentation of the memory). To form a multiplexed of data bus and address bus, four bits of 8086 address bus are grounded.
The memory bus consists of two main parts: the address bus and the data bus. The address bus transmits the addresses of memory locations, allowing the CPU to specify where data should be read from or written to. The data bus, on the other hand, carries the actual data being transferred between the CPU and memory. Together, these components facilitate communication between the processor and memory.