ARM announces its first 64-bit architecture

ARM has made the final leap to challenging Intel in the data centre: the launch of the ARMv8 architecture, which paves the way for 64-bit ARM-based processors.

Interestingly, that's exactly the opposite of what ARM executive veep Ian Drew told thinq_ during an interview at this year's Computex back in June. "Our market seems to be doing OK on 32-bit at the moment," he explained. "You walk the floor at Computex, you see lots of tablets, you see the performance of these things - nobody's coming to us and asking for 64-bit."

Perhaps nobody was asking for it, but ARM is delivering it anyway: announced late last night, the ARMv8 architecture replaces the existing 32-bit ARMv7 architecture - which has a 40-bit memory addressing space for applications where more than 4GB of RAM are required - with a true, native 64-bit architecture.

It's a major move for ARM, and one that is long overdue: IBM first introduced 64-bit data words with the 7030 Stretch supercomputer in 1961, while one-time ARM rival MIPS produced the first true 64-bit microprocessor - the MIPS R4000 - in 1991. This was joined by Digital Equipment Corporation's Alpha in 1992, and Intel - ARM's current target - announced the IA-64 architecture in 1994 in partnership with Hewlett Packard.

Even with the 40-bit extensions added for large memory support in the Cortex-A15, that left ARM as one of the only 32-bit architecture vendors around. While that doesn't matter so much in the world of tablets and smartphones - where having more than 1GB of memory is a rarity, and more than 4GB nearly unheard of - it was a big stumbling point to data centre adoption, regardless of Drew's claims at Computex.

According to ARM's documentation on the ARMv8 instruction set architecture, all the classic features of the ARMv7 ISA will be implemented, and chips built around ARMv8 will be able to operate in either 64-bit or 32-bit modes - suggesting that ARM's licensees will make the move to ARMv8 even if they have no intentions to run 64-bit code.

Applied Micro has already announced support for the ARMv8 architecture, planning to be one of the first to market with its Micro X Gene system-on-chip design, which will offer up to 128 processing cores at speeds of up to 3GHz. More announcements are expected next year, with the first prototype ARMv8-based servers expected to hit in 2014.

For now, server manufacturers looking to use low-power ARM chips will have to make do with the Cortex-A15, an ARMv7 chip with 40-bit memory addressing capabilities.