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An 8051 chip could be sold as a ROM-less 8031, as the 8051's internal ROM is disabled by the normal state of the EA pin in an 8031-based design. A vendor might sell an 8051 as an 8031 for any number of reasons, such as faulty code in the 8051's ROM, or simply an oversupply of 8051s and undersupply of 8031s. Intel P8044AH microcontroller
Among the first of the AVR line was the AT90S8515, which in a 40-pin DIP package has the same pinout as an 8051 microcontroller, including the external multiplexed address and data bus. The polarity of the RESET line was opposite (8051's having an active-high RESET, while the AVR has an active-low RESET ), but other than that the pinout was ...
Intel 8051 / MCS-51 family NOP: 1 0x00 Intel 8080, Intel 8085, Z80: NOP: 1 0x00 DEC Alpha: NOP: 4 0x47FF041F Opcode for BIS r31,r31,r31, an instruction that bitwise-ORs the always-0 register with itself. AMD 29k: NOP: 4 0x70400101 Opcode for aseq 0x40,gr1,gr1, an instruction that asserts that the stack register is equal to itself. [3] ARM A32 ...
Compilers and assemblers are used to convert both high-level and assembly language code into a compact machine code for storage in the microcontroller's memory. Depending on the device, the program memory may be permanent, read-only memory that can only be programmed at the factory, or it may be field-alterable flash or erasable read-only memory.
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.
For example, Schmitt-trigger inputs, high-current output drivers, optical isolators, or combinations of these, may be used to buffer and condition the GPIO signals and to protect board circuitry. Also, higher-level functions are sometimes implemented, such as input debounce , input signal edge detection, and pulse-width modulation (PWM) output.
For most Microchip microcontrollers, ICSP programming is performed using two pins, clock (PGC) and data (PGD), while a high voltage (12 V) is present on the Vpp/MCLR pin. Low voltage programming (5 V or 3.3 V) dispenses with the high voltage, but reserves exclusive use of an I/O pin.
Bit banging is a term of art that describes a method of digital data transmission as using general-purpose input/output (GPIO) instead of computer hardware that is intended specifically for data communication.' [1] Controlling software is responsible for satisfying protocol requirements including timing which can be challenging due to limited host system resources and competing demands on the ...