[sdiy] Art of electronics computer

[Magnus Danielson]

On 01/09/2012 06:28 PM, David Anderson wrote:
> Tim's not the only 1802 fan left in the world:
> http://www.sparetimegizmos.com/Hardware/Elf2K.htm
> http://www.retrotechnology.com/memship/memship.html
>
> The 1802 was available in silicon on sapphire, which gave it greater
> resistance to radiation than most ICs at the time.

Silicon on sapphire (SOS) is supperious to normal CMOS processes in 
radhard environments since the bulk silicon has only PN junction 
protection barriers between the transistors, and ionisation radiation 
can upset that. With SOS the transistors is built on top of the 
isolating sapphire, which is tricky since the sapphire and silicon 
structure does not really match, but the end result is that transistors 
is far more effectively isolated than the bulk silicon would ever achieve.

This from the memory as I learned it ages ago, so some of the memory 
cells might have degraded.

Cheers,
Magnus

> It's apparently still being used in new designs.
>
>
>
> On 1/9/2012 12:17 PM, Tim Daugard wrote:
>> From: "Harry Bissell" <harrybissell at wowway.com>
>>
>>
>>> 1802 ? are you planning some rad-hard sequencer or something ?" :^)
>>>
>>> (for those not in the know, the 1802 has superior performance in
>>> radiation environments due to the
>>> forgiving nature of its CMOS process and large (gigantic, by today's
>>> standards) geometry.
>>>
>>> Perhaps the last things on earth will be a dead flower and a live
>>> cockroach, jamming to your 1802 beat box...
>>
>> I'm in the process of installing Mag Core memory chips also. That
>> should help keep the system running for a thousand years.
>>
>> Tim Daugard
>> AG4GZ 30.4078N 86.6227W Alt: 12 feet above MSL
>>
>> No longer on line: http://members.cox.net/synthfred/h_toctop.htm
>> (Fred's online edition) }:-(
>>
>>
>>
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