4 ms·
Back in the late 70s and 80s, many computers and other digital systems were actually designed using basic blocks similar to this. Since chip layout is by far t
by retrac 2y ago
Back in the late 70s and 80s, many computers and other digital systems were actually designed using basic blocks similar to this. Since chip layout is by far the biggest expense (especially back then) it made sense to design just one customizable chip, and then produce it with different metal layers to configure it into various arrangements, so it is relatively easily "programmed" just before manufacturing. DEC's ill-fated VAX 9000 was done in this way, probably the last great pre-CMOS processor design, with hundreds of ECL gate array chips all based on a couple die patterns. Unfortunately the benefits of sheer density from CMOS were undeniable. When they crammed the VAX into a $1000 CMOS microprocessor, it outperformed the $1 million VAX 9000 four years later. These days it's relatively uncommon as a technique except for rapid prototyping. With standard cell ASIC designs, a gate array cell able to perform any function is still an option, but modern design tools make it much easier to use more optimized logic.
- basementcat 2y agoI think a "field programmable" device is distinct from a "mask programmable" device. The latter is potentially much simpler (no RAM, potentially a "sea of muxes" (or nands) while the former needs RAM, shift register logic, additional I/O and so on.
- mafuyu 2y agoIf I'm remembering correctly, Jeri Ellsworth said in an interview that the CastAR glasses were fabbed on a gate array. I thought it was super cool how they were able to prototype a device on FPGA and get chips fabbed as a consumer electronics startup. It probably makes less and less sense nowadays, with how cheap and capable MCUs have gotten.
- EgoIncarnate 2y agoI think you might be confusing CastAR with the C64 toy stuff she did early on. That was initially FPGA and then converted to custom gate array. If I recall there was an issue in that the FPGA initialzed it's memory and the custom silicon didn't which lead to some heart pounding moments when it failed initial bring up. I don't think CastAR/Tilt5 isn't doing enough units to justify custom silicon. I believe they settled on the Intel Movidius VPU for the bulk of the glasses "brains".
- mafuyu 2y agoAhh, yeah I think you’re right. The story left a big impression on me, but I guess not well enough for me to remember the details. :)
- throwaway48476 2y agoSounds like LSI. https://en.wikipedia.org/wiki/LSI_Corporation https://en.wikipedia.org/wiki/LSI_Corporation