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In 1947, the design of the MIT Whirlwind introduced the concept of a control store as a way to simplify computer design and move beyond ad hoc methods. The control store is a diode matrix : a two-dimensional lattice, where one dimension accepts "control time pulses" from the CPU's internal clock, and the other connects to control signals on ...
An address decoder is a commonly used component in microelectronics that is used to select memory cells in randomly addressable memory devices. Such a memory cell consists of a fixed number of memory elements or bits. The address decoder is connected to an address bus and reads the address created there.
Magnetic core memory was the standard form of computer memory until displaced by semiconductor memory in integrated circuits (ICs) during the early 1970s. [ 10 ] Prior to the development of integrated read-only memory (ROM) circuits, permanent (or read-only ) random-access memory was often constructed using diode matrices driven by address ...
In computing, serial presence detect (SPD) is a standardized way to automatically access information about a memory module.Earlier 72-pin SIMMs included five pins that provided five bits of parallel presence detect (PPD) data, but the 168-pin DIMM standard changed to a serial presence detect to encode more information.
The instruction memory, implemented as read-only memory from the viewpoint of the computer and designated ROM, holds assembled binary program code for execution. The random access memory, called RAM, provides storage for an executing program’s data and provides services and storage areas for the computer’s memory-mapped I/O mechanism. Data ...
The design of instruction sets is a complex issue. There were two stages in history for the microprocessor. The first was the CISC (Complex Instruction Set Computer), which had many different instructions. In the 1970s, however, places like IBM did research and found that many instructions in the set could be eliminated.
Separate from the stack definition of a MISC architecture, is the MISC architecture being defined by the number of instructions supported. Typically a minimal instruction set computer is viewed as having 32 or fewer instructions, [1] [2] [3] where NOP, RESET, and CPUID type instructions are usually not counted by consensus due to their fundamental nature.
Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.