Editing Intel MCS-51 (section)

== Use as intellectual property ==
Today, 8051s are still available as discrete parts, but they are mostly used as [[silicon intellectual property]] cores.<ref>{{Cite web|url=https://technobyte.org/8051-not-old-still-popular-use-why/|title=Why do we have to use the 8051? Isn't it too old?|last=Hussaini|date=20 August 2019|website=Technobyte|access-date=5 July 2023}}</ref> Available in hardware description language source code (such as [[VHDL]] or [[Verilog]]) or [[FPGA]] [[netlist]] forms, these cores are typically integrated within embedded systems, in products ranging from [[USB flash drive]]s to washing machines to complex wireless communication [[System on a chip|systems on a chip]]. Designers use 8051 silicon IP cores, because of the smaller size, and lower power, compared to 32-bit processors like [[ARM Cortex-M|ARM Cortex-M series]], [[MIPS architecture|MIPS]] and BA22.{{Citation needed|date=July 2018}}

Subsequent 8051 core designs have increased performance while retaining compatibility with the original MCS 51 instruction set. The original Intel 8051 was a microcode engine using 12 clocked microcode cycles per machine cycle to minimize the number of NMOS logic gates consuming power in passive resistive pull-ups. Most instructions executed in one or two machine cycles. At the typical maximum clock frequency of 12&nbsp;MHz the original 8051 types execute one million single-cycle instructions, or 500,000 two-cycle instructions, per second. The change to CMOS using active P-channel FET pull-ups makes it possible to realize the core without microcode. Enhanced 8051 IP cores run at one clock cycle per machine cycle. With clock frequencies of up to 450&nbsp;MHz an 8051-compatible processor can execute up to 450 million instructions per second.