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This argument used to come up when I worked at Cambridge Silicon Radio, where we made ASICs. We made our own CPU designs for those ASICs. Some of the engineers
by abainbridge 7y ago
This argument used to come up when I worked at Cambridge Silicon Radio, where we made ASICs. We made our own CPU designs for those ASICs.
Some of the engineers thought making our own CPU designs was a stupid idea and some thought that switching to ARM designs was a stupid idea. The only fact I have is that our CPU designs were not the main cause of bugs in our chips. If you asked the digital designers, they'd say things like, "Why are software engineers so interested in CPU designs. The kinds of embedded CPUs we need are easy to design. Implementing a correct power management state machine is hard. Implementing an efficient WiFi PHY is hard. Get off my lawn..."
Some problems with putting ARM CPUs in our chips were: a) integration engineering costs (ie find a way to multiplex some existing pins on the package with the jtag debug port), b) having to do price and contract negotiation with ARM (that part of the company was less efficient than the digital engineering team), c) finding that the change you wanted to make to the chip was incompatible with the ARM contract you'd just spent 6 months negotiating.
- panpanna 7y agoI believe CSR went out of business after burning an investment of $1bn with nothing to show for. Not trying to be hostile, just pointing out how costly "let's design our own soc, how hard can it be?" is.
- lnsru 7y agoAre we talking about same CSR? It’s still in business. It’s now part of Qualcomm: https://en.m.wikipedia.org/wiki/CSR_(company) https://en.m.wikipedia.org/wiki/CSR_(company)
- panpanna 7y agoHmmm.. I stand corrected. I know a few people who joined ARM after CSR closed down but that could be just some offices shutting down. (not an arm employee, btw)
- abainbridge 7y agoThe offices in Cambridge didn't shutdown. Approximately Samsung bought one building (WiFi), and a year later Qualcomm bought the other (BT + audio). Both Samsung and Qualcomm had rounds of redundancies but have also both hired lots of people. My guess is both offices are about the same fullness as they were ten years ago.
- btashton 7y agoBut you also left developers with really hard to use dev tools based on a fork of gcc. The arch also left you having to do all kinds of mental gymnastics when writing code to make sure you were keeping the size down. That said the chips certainly did there job at a good price point once you got everything stable and fixes made to the binary blobs that you had no way to debug.
- abainbridge 7y ago> But you also left developers with really hard to use dev tools based on a fork of gcc Yep. Sorry about that. Not that it was my fault. Anyhow, I guess my belief is that a similar company to CSR could put RISCV cores in their chips now, which would avoid the problem you describe and some of the problems I described with using ARM.
- ansible 7y agoAh, the good old XAP processor. For a while you guys were marketing a BC03 or BC04 era chip as a general-purpose microcontroller with digital audio functions.