Woodstock Display Upgrade (a sight for sore eyes)

[markhen]

@Stefan - I've implemented all the defined SI prefixes (Y,Z,E,P,T,G,M,k,h,da,d,c,m,mu,n,p,f,a,z,y). I debated for a while whether to have some sort of "exponent follows" marker - or not. After playing around with various options I liked the up arrow. I agree that no marker is really required, but I think when first using this mode it's a bit confusing to see a single letter "floating" out on the right?!? Very easy to remove that marker!!

@BobVA - the battery pack circuit is dead simple - see attached. I use 2 x 3.7V (nominal) 900mAh LiPo cells connected in parallel. They are a SNUG fit in the battery case, which needs a little surgery to make the battery opening larger. The charger connector is mounted on the circuit board in the pack (0.1" header) and charger cable can be inserted either way (for safety/convenience). Fully charged cell is ~4.2V, the 2 x silicon diodes drop a bit more than 1.2V under load, so the calculator doesn't see over 3V (under load). This is the same as it would see if using 2x fresh alkaline AA cells, and we know the calcs work fine on this voltage. When the batteries drop to 3.7V (which is about where we should recharge), the calc sees about 2.5V, which is higher than the calc low battery threshold, so the low battery indication now really means "stop and recharge NOW"!! As you can see, there is no inherent parasitic drain in the battery pack itself, and it will supply standby current for 25C or 29C models. I've been using this in a 29C with no issues. I guess there is a concern in the C models that since the standby current draw is very small, the diode drops will be <<0.6V, and the CMOS memory will see something like ~3.6V with a fully charged LiPo? Accidently plugging the calc into a standard charger will not damage the battery pack (hopefully no one here does this with Woodstocks FOR ANY REASON nowadays?!) but will almost certainly damage the calc :-(

@Didier - I mentioned this in post #12 - "The code looks at the calculator display and decides if it has enough display digits to display all visible digits, or not. If there is no minus sign on the mantissa, it will use the left-most display digit to display a digit (this is something the base calculator never does (in "RUN" mode)). In the event the display mode and display value exceed 12 digits, the least significant digit is dropped (truncated). This could easily be changed to round (vs. truncate)." This is probably a pretty rare case for most users?