Reply to post: Re: I've always wanted to know

Picking apart the circuits in the ARM1 – the ancestor of your smartphone's brain

Tom 7 Silver badge

Re: I've always wanted to know

In the early days - when there were less than about 5k devices on a chip there was not a lot of automation available and many hours were spent laying out stuff and you would learn what bits looked like. Worse than that - I used to layout NMOS on a tectronic storage scope which wrote on a green screen with a very bright stream of electrons that left a glow that was a bit brighter than the dark green background, After a long day on one of these you could stand in the pub and whole parts of the circuit would literally flash before your eyes!

Towards the ends of the eighties a huge amount of CAD had been developed and you would only hand craft (and hence recognise) repeated parts to get the maximum utilisation of space and these parts would stay with you for a long time.

I worked on some (for then) ultra high speed bipolar and the high (relatively) power consumption meant chips didnt have too many components and were largely pad limited the pads the connecting wires were attached were on 100u 'grid' so you could spend a month or more trying to shrink some part of the circuit by 10 or 20u so the whole chip size would drop 100u and you could get another 15 devices from a 4" die. When you spend that amount of time on something you remember it.

Not sure what its like these days - wanted to get into it again but they wanted £40k just to see the process details FFS.

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