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Found these inside a non-working 71B
03-11-2018, 08:27 PM
Post: #31
RE: Found these inside a non-working 71B
(03-11-2018 08:15 PM)rprosperi Wrote:  
(03-11-2018 07:53 PM)MikeSD Wrote:  I think i will test these chips in another 71b thats known working. Math, FORTH and 64K RAM would be a good find, in a calc i marked junk a few years when it didnt work when I turned it on, assuming they are working.

Keep in mind the FORTH ROM Module actually contained 2 ROMs; one is fixed address at 0xE0000 and the other is loadable anywhere, placed at the 'right' address by the OS' config routines.

Perhaps the board with the very different layout is a board that holds the 32KB ROM that is fixed at 0xE0000 ? Makes sense that it would have fewer leads, I think...

It appears to have all the connections it needs there are 3 pins next to +5 that are of no use to a RAM or ROM module they are there because these modules are designed to be put into front side plugins The fourth missing connection is Dout which is not brought back to the board because it goes on to connect to the other added RAM and ROM modules.

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Messages In This Thread
RE: Found these inside a non-working 71B - Paul Berger (Canada) - 03-11-2018 08:27 PM
What's U10? - Dave Frederickson - 03-15-2018, 03:43 PM

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