Connecting Memory Modules with the CPU
A crucial component of computer design is memory interfacing, which makes it easier for different kinds of memory modules and a computer's central processing unit (CPU) to communicate. In order to allow the CPU to read from and write to memory effectively, hardware and protocols must be designed and put into place.
Static random-access memory (SRAM), dynamic random-access memory (DRAM), and non-volatile memory, including flash memory, are commonly used in memory interfaces in contemporary computers.
Ensuring smooth data communication between the CPU and memory while maximizing speed, dependability, and affordability is the main objective of memory interfacing. Memory controllers and bus interfaces are examples of specialized integrated circuits that are frequently needed for this.
Memory controllers handle operations including addressing, data transmission, and error detection and correction as well as the flow of data between the CPU and memory modules.
Systems to access specific memory locations
Synchronous and asynchronous communication techniques
Physical and logical connections between components
Organization of memory types by speed and cost
Methods to improve data access speed
The seamless functioning of computer systems depends on effective memory interfacing, which affects things like program performance, multitasking ability, and user experience in general. Memory interface strategies must change to provide larger capacities, quicker speeds, and new kinds of memory modules as memory technology grow, guaranteeing continuous improvements in computing power.
There are typically "n" address pins and "m" data pins (also known as output pins) on a semiconductor memory IC.
Possessing two power supply pins, one for ground and the other for attaching the necessary supply voltage (V).
Control signals required for static RAM:
Control signals required for EPROM read operations:
"n" address pins to select memory locations
"m" data pins for input/output operations
VCC for power supply and GND for ground
Chip select, output enable, and write enable signals
Assembly language program to add two numbers:
MVI A, 2H - Moves the immediate value 2H (hexadecimal) into the accumulator (register A)
MVI B, 4H - Moves the immediate value 4H (hexadecimal) into register B
ADD B - Adds the contents of register B to the accumulator and stores the result in the accumulator
Assembly language is specific to a given processor. For e.g. assembly language of 8085 is different than that of Motorola 6800 microprocessor.
Microprocessor understands Machine Language only! Microprocessor cannot understand a program written in Assembly language.
A program known as Assembler is used to convert a Assembly language program to machine language.
Assembly language program written by programmer
Converts assembly code to machine code
Machine language code that microprocessor can execute
The programming model of 8085 microprocessor shows the internal registers and their organization that are accessible to the programmer. These registers are used to store data, addresses, and control information during program execution.
S Z AC P CY
| Register | Description |
|---|---|
| A (Accumulator) | 8-bit register used for arithmetic and logical operations |
| B, C, D, E, H, L | 8-bit general-purpose registers that can be used individually or as register pairs (BC, DE, HL) |
| Flags Register | Contains 5 status flags: Sign (S), Zero (Z), Auxiliary Carry (AC), Parity (P), and Carry (CY) |
| Stack Pointer (SP) | 16-bit register that points to the top of the stack in memory |
| Program Counter (PC) | 16-bit register that contains the address of the next instruction to be executed |
| Instruction Register | Holds the current instruction being executed |
| Temporary Register | Used internally by the processor for temporary storage during operations |