FRAM71B

[Dave Frederickson]

(05-22-2016 08:26 AM)Hans Brueggemann Wrote:  as for 4): Sylvain says:

Quote:It makes sense for me that page 0 & 1 to be controlled with the CN2:1 jumper but why include page 2 with it ?
If I change the OS version with the Jumper, I do not necessarily want to change my FRAM71 config with it.

that is exactly the configuration that you would be using most of the time. so, for this use-case you would duplicate the BOT_FRAM config into the TOP_FRAM, and you should be all set.
however... consider the case where you hold the DIAG ROM in TOP_FRAM. you may now set the TOP_FRAM config differently. and by setting that config to all zero, you are now able to test "real" modules with the DIAG ROM, without destroying any of the FRAM contents. well, that's at least how it is supposed to work ;o)
the modified CN2:1 functionality still preserves the option to set up the HP-71B with some kind of "dual personality", but also allows you to quickly alter the base setup of the calculator for intermediate other purposes.

We might be talking about two different jumpers. Typically to change the OS the SYSRAM feature is enabled, via J1 and enabling OD, which swaps in the OS in banks 0 and 1. CN2:1 is the TOP/BOTTOM FRAM jumper. I would expect bank 2 to be swapped with CN2:1, but why swap banks 0 and 1 also? Doesn't making banks 0 and 1 configurable, like banks 3 - F, more flexible?

Dave