Editing Intel MCS-51 (section)

=== Derivative features ===
{{As of|2013}}, new derivatives are still being developed by many major chipmakers, and major compiler suppliers such as [[IAR Systems]], [[Keil (company)|Keil]] and [[TASKING]]<ref>{{Cite web |url=https://www.tasking.com/products/8051 |title=8051 Software Development Toolset - Overview |website=TASKING |access-date=2025-02-13}}</ref> continuously release updates.

MCS-51-based microcontrollers typically include one or two [[UART]]s, two or three timers, 128 or 256&nbsp;bytes of internal data [[RAM]] (16&nbsp;bytes of which are bit-addressable), up to 128&nbsp;bytes of [[I/O]], 512&nbsp;bytes to 64&nbsp;KB of internal program memory, and sometimes a quantity of extended data RAM (ERAM) located in the external data space. 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. With a 12&nbsp;MHz [[clock frequency]], the 8051 could thus execute 1&nbsp;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 (denoted "1T") and have clock frequencies of up to 100&nbsp;MHz, thus being capable of an even greater number of instructions per second. All [[Silicon Labs]], some [[Dallas Semiconductor|Dallas]] (now part of [[Maxim Integrated]]) and a few [[Atmel]] (now part of [[Microchip Technology|Microchip]]) devices have [[Single-cycle processor|single-cycle cores]].<ref name=":0">{{Cite web |title=8-bit Microcontrollers – 8-bit MCUs – EFM8 |website=Silicon Labs |url=https://www.silabs.com/mcu/8-bit |access-date=2021-06-21 |language=en}}</ref><ref>{{Cite web |title=Site Search |website=Maxim Integrated |url=https://www.maximintegrated.com/en/site-search.html#q=DS80&sort=relevancy&f:@common_product_hierarchy=%5BMCU%20-%20Microcontroller%5D |access-date=2021-06-21 |archive-date=2021-06-24 |archive-url=https://web.archive.org/web/20210624210156/https://www.maximintegrated.com/en/site-search.html#q=DS80&sort=relevancy&f:@common_product_hierarchy=%5BMCU%20-%20Microcontroller%5D |url-status=dead }}</ref><ref name=":1">{{Cite web |title=8051 MCUs |website=Microchip Technology |url=https://www.microchip.com/en-us/products/microcontrollers-and-microprocessors/8-bit-mcus/8051-mcus |access-date=2021-06-21}}</ref>

8051 variants may include built-in reset timers with [[Brownout (electricity)#Digital systems|brown-out]] detection, on-chip oscillators, self-programmable [[flash ROM]] program memory, built-in external RAM, extra internal program storage, [[bootloader]] code in ROM, [[EEPROM]] non-volatile data storage, [[I2C|I<sup>2</sup>C]], [[Serial Peripheral Interface|SPI]], and [[USB]] host interfaces, [[controller–area network|CAN]] or [[Local Interconnect Network|LIN]] bus, [[Zigbee]] or [[Bluetooth]] radio modules, [[pulse-width modulation|PWM]] generators, analog [[comparator]]s, [[analog-to-digital]] and [[digital-to-analog converter]]s, [[real-time clock|RTCs]], extra counters and timers, in-circuit [[debugging]] facilities, more interrupt sources, extra power-saving modes, more or fewer parallel ports etc. Intel manufactured a mask-programmed version, 8052AH-BASIC, with a [[BASIC]] interpreter in ROM, capable of running user programs loaded into RAM.

MCS-51-based microcontrollers have been adapted to extreme environments. Examples for high-temperature variants are the Tekmos TK8H51 family for −40{{nbsp}}°C to +250{{nbsp}}°C<ref>{{cite web
 | title=TK80H51 250&nbsp;°C Microcontroller
 | url=http://www.tekmos.com/products/80c51-microcontrollers/tk80h51-250-c-microcontroller
 | publisher=Tekmos Inc.
 | access-date=23 August 2017
 | archive-url=https://web.archive.org/web/20170820093849/http://www.tekmos.com/products/80c51-microcontrollers/tk80h51-250-c-microcontroller
 | archive-date=20 August 2017
 | url-status=dead
 }}</ref> or the [[Honeywell]] HT83C51 for −55{{nbsp}}°C to +225{{nbsp}}°C (with operation for up to 1 year at +300{{nbsp}}°C).<ref>
{{cite web
 | title=HIGH TEMPERATURE 83C51 MICROCONTROLLER
 | url=http://www.keil.com/dd/docs/datashts/honeywell/ht83c51.pdf
 | publisher=Honeywell
 | access-date=23 August 2017
}}</ref> [[Radiation hardening|Radiation-hardenend]] MCS-51 microcontrollers for use in spacecraft are available; e.g., from [[Cobham plc|Cobham]] (formerly [[Aeroflex]]) as the UT69RH051<ref>{{cite web
 | title=Microcontrollers and Microprocessors
 | url=http://ams.aeroflex.com/pagesproduct/prods-hirel-uprocessors.cfm
 | publisher=Cobham Semiconductor Solutions
 | access-date=23 August 2017
 | archive-date=23 August 2017
 | archive-url=https://web.archive.org/web/20170823020620/http://ams.aeroflex.com/pagesproduct/prods-hirel-uprocessors.cfm
 | url-status=dead
 }}</ref> or from NIIET as the 1830VE32 ({{langx|ru|1830ВЕ32}}).<ref name=niiet/>

In some engineering schools, the 8051 microcontroller is used in introductory microcontroller courses.<ref>{{Cite web |url=http://play.tojsiab.com/WFhtU3d2djNXckUz |title=Download link Youtube: ELEC2700 – 8051 Ultrasonic Radar |access-date=2017-08-22 |archive-url=https://web.archive.org/web/20170822215715/http://play.tojsiab.com/WFhtU3d2djNXckUz |archive-date=2017-08-22 |url-status=dead }}</ref><ref>Archived at [https://ghostarchive.org/varchive/youtube/20211205/H9sDn89EvD8 Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20200608025501/https://www.youtube.com/watch?v=H9sDn89EvD8&gl=US&hl=en Wayback Machine]{{cbignore}}: {{cite web| url = https://www.youtube.com/watch?v=H9sDn89EvD8| title = ELEC2700 Assignment 1 2014: 1D Pong | website=[[YouTube]]| date = 10 April 2014 }}{{cbignore}}</ref><ref>{{Cite web |url=https://www.zookal.com/ |title=ELEC2700 – Computer Engineering 2 (University of Newcastle Textbooks) |website=Zookal |access-date=2017-08-22 |archive-date=2017-07-27 |archive-url=https://web.archive.org/web/20170727171633/https://www.zookal.com/ |url-status=dead }}</ref><ref>{{cite web |url=http://s3.amazonaws.com/f01.justanswer.com/88willy/2012-06-29_065532_assignment_03.pdf |access-date=30 April 2023 |date=29 June 2012 |website=JustAnswer |title=ELEC2700 Assignment 3: Ultrasonic Radar}}</ref>