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Comment by zirkonit

14 hours ago

In consumer space, 69 KB of RAM (138 x 4 kbit chips) would cost around $1700 70s dollars for the entire package, ~$10k in modern dollars.

Radioationed hardened for space though — $50k-$100k in 70s dollars, roughly the price of a Silicon Valley house back then - $300k-$600k in today's money.

7 comments

zirkonit

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saltyoldman  13 hours ago

Wouldn't they just put a lead plate around the computer? That can't cost 100k in 70s

  • kulahan  13 hours ago

    Lead makes things worse, not better. High-energy particles go straight through a couple mm of lead no problem, and lead itself is radioactive anyways. The problem is when a particle punches straight through a chip, leaving some energetic charge behind. You won't stop that with a paper-thin layer of lead.

    Also, lead is extremely dense.

    • hunterpayne  12 hours ago

      "and lead itself is radioactive anyways"

      Um, I guess in that there are naturally occurring isotopes of lead that are unstable. But those are very rare and can be removed. By this standard, the chips themselves are radioactive since they are made of silicon. By this standard, you, everything you eat, every plant and animal is radioactive since there are trace isotopes of carbon that are radioactive (that's how carbon dating works). And sunlight is very radioactive by this standard.

      However, the materials we actually use in chips is highly processed and radioactive isotopes will likely be removed if a centrifuge was used in any step in concentration process. Likewise the lead used in a space shield will probably have similar processing of the material

      "Also, lead is extremely dense."

      This is the real reason lead isn't used. There are plenty of other elements that shield ionizing radiation quite well and are less dense. However, they are also more expensive than lead which is why we use lead on earth for shielding (its cheap) and use something else in space (where density is more important than price).

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  • tliltocatl  9 hours ago

    Because lead turns a single high-energy particle (that would disturb a single bit and punch through) into a shower of many low-energy particles (that would disturb many bits AND induce lattice damage over a wide area).