This made them memory organization of 8051 microcontroller pdf suitable for battery-powered devices. MCS-251 family of binary compatible microcontroll
This made them memory organization of 8051 microcontroller pdf suitable for battery-powered devices. MCS-251 family of binary compatible microcontrollers.
With one instruction, the 8051 can switch register banks versus the time consuming task of transferring the critical registers to the stack, or designated RAM locations. The main program then performs serial reads and writes simply by reading and writing 8-bit data to stacks. External RAM and ROM share the data and address buses. The original 8051 core ran at 12 clock cycles per machine cycle, with most instructions executing in one or two machine cycles. 8051 could thus execute 1 million one-cycle instructions per second or 500,000 two-cycle instructions per second. Enhanced 8051 cores are now commonly used which run at six, four, two, or even one clock per machine cycle, and have clock frequencies of up to 100 MHz, and are thus capable of an even greater number of instructions per second. Dallas and a few Atmel devices have single cycle cores.
ROM, capable of running user programs loaded into RAM. MCS-51 based microcontrollers have been adapted to extreme environments. MCS-51 microcontrollers for use in spacecraft are available e. In some engineering schools the 8051 microcontroller is used in introductory microcontroller courses.
8051 is the original name by Intel with 4 KiB ROM and 128 byte RAM. Variants starting with 87 have a user programmable EPROM memory, sometimes UV erasable. 8031 and 8032 are ROM-less versions, with 128 and 256 bytes RAM. The last digit can indicate memory size, e. 8052 with 8 KiB ROM, 87C54 16 KiB EPROM, and 87C58 with 32 KiB EPROM, all with 256 RAM. RAM, special function registers, program memory, and external data memory. Most 8051 systems respect this distinction, and so are unable to download and directly execute new programs.
W data access to program memory. 8-bit address space, allowed addresses 0 through 0xFF. IRAM from 0x00 to 0x7F can be accessed directly. Most 8051 clones also have a full 256 bytes of IRAM. IRAM, at addresses 0x80 to 0xFF, and are accessed directly using the same instructions as for the lower half of IRAM. 64 KiB of read-only memory, starting at address 0 in a separate address space. It may be on- or off-chip, depending on the particular model of chip being used.