Fixing small plastic... things

[Christian Corti]

On Wed, 8 Dec 2010, Tony Duell wrote:
>> No, I haven't. The objective is to make a precise gate-level simulation
>> of the calculator, both for understanding and which can be used to
>> track down faults in a broken instance of the real thing. Patents
>> generally don't provide the level of accuracy for that objective, so it
>> generally doesn't occur to me to look to patents for these purposes.
>
> As n aside, some of the HP desktop calcualtor patents are very detailed,
> and include sechematics, commented firmware source, extension ROM
> sources, and so on. But as you imply, there are often suble differences
> between the machien described i nthe patent and the actual prodcution
> model. I regard these patents as a very useful resource and well worth
> reading, but you need to check against an actual machine.

Sure, but the patents help identify signal names and understand the 
priciples of the machine. You can't easilly find out how a machine works 
by just looking at the flip-flop or some random logic. We had to repair 
some Friden 132 boards just a few weeks ago, the block diagrams and 
descriptions in the patents were quite helpful.

Christian