Classification of Microcontrollers Over the years the micro-controllers have evolved to new height. There are number of players who manufacture them. So, it becomes essential to know what are different types of micro-controllers. They can be categorized based on size of registers, make, memory architecture, features etc. These are listed in table 1.1 below: 8051(Intel, Philips, Atmel, Siemens, Dallas) ATMEL, TI, National, Fairchild, Hitachi, OKI, Intel, Toshiba, Microchip, Zilog, Rockwell, Motorola, ST Microelectronics, Rabbit, Silicon Laboratories, NXP Semiconductors Table 1.1 Micro-controller Classification 1 Based on Architecture Harvard Architecture Princeton(Von-Neuman) Architecture 2 Size of Registers 4-Bit: Hitachi-HMCS40, National-COP420, TI-TMS1000 8-Bit: Intel- 8048, 8051 PIC-16C56, Zilog-Z86C83, Motorola-6805, 68HC11, TI-TMS7500, Infineon-XC800 16-Bit Intel-80C196, National-HPC16164, Hitachi-H8/532, Infineon-XE166 32-Bit ATMEL-XMEGAA3BU, SAMD20, Intel-i960, AVR32, Infineon-XMC4000, NXP-LPC4000 3 Memory Embedded RAM and ROM  Additional External Memory 4 Instruction Set RISC CISC CISC implemented in RISC core 5 Family 8051 PIC AVR  ARM Criteria of Selection: Selection of a particular micro-controller depends