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by simne
1480 days ago
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Universal analog chips are cool, but extremely expensive, and their analog performance is moderate. - Their analog performance is enough for simple hobbyists projects, but for commercial, need something with much more precision - 18 bit or more. That's what differ analog computers from digital - in analog easy achievable ~ 10-12 bits, but more are expensive; in digital, could trade precision for speed - for example calculate 64 bit on 32 bit hardware, which is at least 4 times slower (in ideal cases, in real more than 4x difference), but double precision worth it. Even more, in digital world, could calculate 32bit or even 64bit on 8bit hardware (really used in microcontroller world), which is extremely slow, but for many cases is fast enough. |
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Really easy achieve 8-10 bits, even 12 bits, but 16 bits or more are hard.
For example, now manufacturers use large matrices with lot of spare parts, and before put chip in case, it's precision measured and cut metal seals, so made very precise parameters.
So in reality, modern analog chips ARE one time programmable analog, but one time analog programming is cheap enough, but rewritable are inadequate expensive.
Also this is reason, why analog computers where extremely popular ~before microcomputers.
- Just because first computers where too slow and have too little memory, to simulate interest for real applications scale of analog circuits.
But digital progress where extremely fast and it scaled very well, so in very short time appear cheap digital computers, which could do 32 bit precision or even 64 bit, on 8 bit hardware. And for analog, 16 bit still hard.
Where you could see race for precision - in analog TVs and in radios, used DAC (or mechanical multi-turn resistor) for frequency tune, and they limit progress of commodity equipment on about 12-14 bit, even when exist professional (scientific) equipment with 20-22bits or even more, but it costs many times more.
Other less easy seen example - in CCD sensors, ADC limit about 32bit, and even when exists market for better solutions, they are not appear, just because very expensive.
For displays this is not important, because most people accept even 24 bit color and because more depth achievable via emulation (yes you may hear about pwm in monitors).