How far we've come in Power ISA

We haven't done a lot of chip pr0n lately, so let's do a little as a fun aside. Recently I bought a naked 601 (in this case a 601+, the second revision) since I figured it would look nice in my computer room along with my POWER9 die, shown at right in their display boxes.

Just how does that old 601, the very first PowerPC, compare with the POWER9? With painstaking precision propping my Pixel 3 on the end of a cereal box for height and eyeballing the distances with a Home Depot yardstick, I lined up both the 601 and the POWER9 die at the same scale, shown here.

The 601+ at left was manufactured on a 0.5 micron CMOS process in 4 layers, measuring 74 square millimetres. This is a die shrink of the original, which was manufactured at 0.6 microns in 4 layers and measured 121 sq mm. Both the 601 and 601+ have a single 32-kilobyte unified L1 cache, which was dispensed with for the 603, and 2.8 million transistors. At 80MHz, the original 601 consumed 8 watts; the 601+ die shrink reduced it to 4 watts at 100MHz.

The POWER9 die at right, on the other hand, is rather larger at 693.37 sq mm. This is almost six times larger than the original 601 and 9.3 times larger than the 601+, but with multiple cores and L1, L2 and L3 cache all crammed onboard in 8 billion transistors — almost 3,000 times more. Shipping POWER9 chips are built on a 14nm FinFET on SOI process in 17 layers and consume between 90 and 190W depending on core count at clock speeds from 2.25GHz to 3.8GHz.

In this oblique view you can see the functional units a bit better. The amount of power in modern Power ISA chips would have been absolutely unthinkable in 1992, particularly at modern process sizes. I, for one, welcome our future POWER10 overlords.

Finally, I've been meaning to post this picture for awhile that Mikey Neuling sent, with Anton Blanchard and Hugh Blemings showing off Microwatt running on an FPGA board (and Hugh's well-traveled Blackbird demo board) at OpenPOWER Europe in October. Now that's a mighty fine logo. The person who came up with that should be congratulated.

If you're States-side, happy Thanksgiving, and if you're not, eat some turkey anyway because it's better than that burger you were going to have.


  1. The 601+ is a real beauty, a classic piece of cpu design <3


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