What are the characterstics features of arm that have been abandoned in order to achieve a 16 bit instruction length
Answers
Microprocessors used as vehicles to teach computer architecture are often mainstream industry-standard devices like the Motorola 68K or the Intel IA32. The processor that is the subject of this paper, the ARM, is beginning to appear in mainstream texts [4]-[5]-[7]. It is an unusual processor from a Cinderella of the microprocessor world rather than a giant like Intel or Texas Instruments. Although a RISC processor like the high performance MIPS or PowerPC, it is found in low-cost consumer applications such as PDAs and cell phones. Its characteristics make it stand out from other processors. It has a delightfully simple core architecture, there are development tools freely available, and it fully supports the computer architecture curriculum.
Advanced RISC Machines Ltd. was founded in the UK in 1990 and changed its name to ARM Ltd. Unusually, ARM does not manufacture microprocessors. It is an IP (intellectual property) company that designs systems and licenses other companies to make them; for example, ARM microprocessors are manufactured by Intel, Texas Instruments, and Samsung. Indeed, ARM 32-bit microprocessors now account for 75% of the world’s embedded 32-bit applications [8]. As we have already stated, students are more likely to be motivated if they study a processor that is in their cell phones.
As there is insufficient space here to discuss all the ARM’s attributes, we list its key features and highlight how they differ from other processors, pointing out the pedagogical advantages.