The paper introduces new a 64-bit instruction set architecture based on EPIC technology, which is called ISA because the traditional microprocessor architectures has limitation to perform instruction sets. The new 64-bit instruction set architecture executes more instructions per cycle, which is referred to as ¡°parallel execution.¡± This 64-bit microprocessor architecture approaches parallel execution combining explicit parallelism with techniques called predication and speculation. The author of the paper explains the 64-bit microprocessor architecture and 3 combinations of an innovative approach with an example of bank lobby.
With traditional architectures, greeter in the bank lobby would not exactly know what customers need to do so the teller at the desk will redirect customers. This is not very efficient. However, with explicit parallelism, bank greeter will exactly know what the operation is needed for customers so it will directly send customers to the right teller.
Moreover, making a predication will make the process more efficient. With traditional architectures, the teller assumes that most customers will withdrawal or deposit so he prepares for the operation of withdrawal. If the teller¡¯s predication is right, it is good, but if the teller¡¯s predication is wrong, then the customers will prepare other operation at the desk and other customers will be waited until it is done. However, 64-bit microprocessor architecture¡¯s teller will prepare both operations when it has spare time. Predication can remove a lot of branches and reduce mispredicts. According to demonstration and benchmarks, predication removed over 50% of the branches and 40% of the mispredicted branches that is very efficient.
Memory latency is another limitation of traditional architectures. On the other had, the 64-bit microprocessor architecture uses speculations that will initiate the compiler load early so ¡°the compiler schedules to allow more time for data to arrive without stalling the processor or slowing its performance.
Before I read this paper, I thought the ISA is referring to ISA slots on motherboard and there is already PCI, AGP, AMR, and so on. However, after reading the paper, my prediction was broken. It seems it is not about these but I am still doubt the 64-bit microprocessor architecture is not these slots on motherboard. PCI is 32-bit and there is now 64-bit PCI slot.
The author explains the 64-bit microprocessor architecture very well and it was very understandable paper with good examples. The 64-bit microprocessor architecture with explicit parallelism, predication, and speculation is reasonable to use for our computers and demonstration and benchmark shows real good efficiency. There should be a computer that is really using this new 64-bit microprocessor architecture and I want to see it. Probably, my computer is also using the 64-bit microprocessor architecture but I don¡¯t know.