MAJC

MAJC (Microprocessor Architecture for Java Computing) was a Sun Microsystems multi-core, multithreaded, very long instruction word (VLIW) microprocessor design from the mid-to-late 1990s. Originally called the UltraJava processor, the MAJC processor was targeted at running Java programs, whose "late compiling" allowed Sun to make several favourable design decisions. The processor was released into two commercial graphical cards from Sun. Lessons learned regarding multi-threads on a multi-core processor provided a basis for later OpenSPARC implementations such as the UltraSPARC T1.

Design elements

Move instruction scheduling to the compiler

Like other VLIW designs, notably Intel's IA-64 (Itanium), MAJC attempted to improve performance by moving several expensive operations out of the processor and into the related compilers. In general, VLIW designs attempt to eliminate the instruction scheduler, which often represents a relatively large amount of the overall processor's transistor budget. With this portion of the CPU removed to software, those transistors can be used for other purposes, often to add additional functional units to process more instructions at once, or to increase the amount of cache memory to reduce the amount of time spent waiting for data to arrive from the much slower main memory. Although MAJC shared these general concepts, it was unlike other VLIW designs, and processors in general, in a number of specific details.