ARM series

The ARM is a 32-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by ARM Holdings. It was known as the Advanced RISC Machine, and before that as the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in terms of numbers produced.^[1][2] They were originally conceived as a processor for desktop personal computers by Acorn Computers, a market now dominated by the x86 family used by IBM PC compatible computers. The relative simplicity of ARM processors made them suitable for low power applications. This has made them dominant in the mobile and embedded electronics market as relatively low cost and small microprocessors and microcontrollers.

As of 2007, about 98 percent of the more than one billion mobile phones sold each year use at least one ARM processor.^[3] As of 2009, ARM processors account for approximately 90% of all embedded 32-bit RISC processors. ARM processors are used extensively in consumer electronics, including PDAs, mobile phones, digital media and music players, hand-held game consoles, calculators and computer peripherals such as hard drives and routers.

The ARM architecture is licensable. Companies that are current or former ARM licensees include Alcatel-Lucent, Apple Inc., Atmel,Broadcom, Cirrus Logic, Digital Equipment Corporation, Freescale, Intel (through DEC), LG, Marvell Technology Group, Microsoft, NEC,Nuvoton, NVIDIA, NXP (previously Philips), Oki, Qualcomm, Samsung, Sharp, STMicroelectronics, Symbios Logic, Texas Instruments,VLSI Technology, Yamaha and ZiiLABS.

ARM processors are developed by ARM and by ARM licensees. Prominent examples of ARM Holdings ARM processor families include theARM7, ARM9, ARM11 and Cortex. Examples of ARM processors developed by major licensees include DEC StrongARM, Freescale i.MX,Marvell (formerly Intel) XScale, Nintendo, NVIDIA Tegra, ST-Ericsson Nomadik, Qualcomm Snapdragon, and the Texas Instruments OMAP product line.

AVR Series

The AVR is a modified Harvard architecture 8-bit RISC single chip microcontroller which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to One-Time Programmable ROM, EPROM, or EEPROM used by other microcontrollers at the time.

The AVR architecture was conceived by two students at the Norwegian Institute of Technology (NTH) Alf-Egil Bogen and Vegard Wollan.The original AVR MCU was developed at a local ASIC house in Trondheim, Norway, where the two founders of Atmel Norway were working as students. It was known as a ?RISC (Micro RISC). When the technology was sold to Atmel, the internal architecture was further developed by Alf and Vegard at Atmel Norway, a subsidiary of Atmel founded by the two architects. The designers worked closely with compiler writers at IAR Systems to ensure that the instruction set provided for more efficient compilation of high-level languages.Atmel says that the name AVR is not an acronym and does not stand for anything in particular. The creators of the AVR give no definitive answer as to what the term “AVR” stands for.Note that the use of “AVR” in this article generally refers to the 8-bit RISC line of Atmel AVR Microcontrollers.

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 identical.