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It seems like they changed a lot and got a hugely different niche. > Instead of adapting an existing microcontroller architecture to plastic, Kumar’s team star
by acover 4y ago
It seems like they changed a lot and got a hugely different niche.
> Instead of adapting an existing microcontroller architecture to plastic, Kumar’s team started from scratch to create a design called Flexicore. “Yield goes down very quickly as you increase gate count,” says Kumar. Knowing that, they came up with a design meant to minimize the number of gates needed. Using 4-bit and 8-bit logic instead of 16-bit or 32-bit helped. As did separating the memory that stores instructions from the memory that stores data. But they also cut down on the number and complexity of the instructions the processor is capable of executing.
> The team further simplified, by designing the processor so it executes an instruction in a single clock cycle instead of the mulit-step pipelines of today’s CPUs. Then they designed logic that implements those instructions by reusing parts, further reducing the gate count. “In general, we were able to simplify the design of FlexiCores by tailoring them to the needs of flexible applications, which tend to be computationally simple,” says Nathaniel Bleier, Kumar's student.
> All of this resulted in a 5.6 square millimeter 4-bit FlexiCore made up of just 2,104 semiconductor devices (about the same as the number of transistors in an Intel 4004 from 1971) versus some 56,340 devices for PlasticARM.
- mrtnmcc 4y agoBy reducing gate count on the processor, they effectively will make the programs longer (more instructions to do the same thing), but it doesn't seem like they are counting memory here..
- londons_explore 4y agoIt does raise the question... Why didn't they just use an Intel 4004... The patents have long expired and plenty of other companies make very old intel clones to out in modern products (eg. Most optical mice use a 50 year old intel to control a custom DSP to do image processing to figure out which way you're moving the mouse)
- derefr 4y agoOne of their (presumably motivated) choices was to use a Harvard architecture; which a 4004 isn’t.
- monocasa 4y agoProbably because NMOS masks don't translate well to this technology. And the chip has big standard cell auto placed and routed energy, so it's probably not that big of a deal for the benefit to be working in a sane HDL before hardening the design. And the ubiquitous 8051s don't typically use Intel masks AFAIK for the same reasons. You really want to optimize for whatever process node currently makes sense.