To reduce the memory costs of these extra instructions, consider a processor with Thumb. Many of today's most popular bit microcontrollers use RISC technology. Many of the complex functions performed in a single, albeit slow, instruction in a CISC processor may require two, three, or more simpler instructions in a RISC. Except in the most speed-critical of embedded devices, the cost of memory is much more critical than the execution speed of the processor.
Join Stack Overflow to learn, share knowledge, and build your career. Connect and share knowledge within a single location that is structured and easy to search. Thumb instructions are 16 bits long,and have a corresponding bit ARM instruction that has the same effect on processor model. The ARM processor has 2 instruction sets, the traditional ARM set, where the instructions are all bit long, and the more condensed Thumb set, where most common instructions are bit long and some are bit long.
Arm Ltd. It also designs cores that implement this instruction set and licenses these designs to a number of companies that incorporate those core designs into their own products. There have been several generations of the ARM design. This limitation was removed in the ARMv3 series, which has a bit address space, and several additional generations up to ARMv7 remained bit. Released in , the ARMv8-A architecture added support for a bit address space and bit arithmetic with its new bit fixed-length instruction set.