What are the final specs for the DM42?

[grsbanks]

(12-16-2017 03:49 PM)revwillie Wrote:  that spllt screen was not as useful as it might appear. I believe it was used more for troubleshooting early on when visual redundancy had more of a purpose.

It happened because "painting" its buffer to the screen was entirely the responsibility of Free42 at the time. Later on, Free42 was patched by SM and the DM42 took control of drawing the screen. This allowed us to break away from the 2-register display and provide the 6 different register layouts now available on the DM42. While this code was being debugged and tested thoroughly by the "army" of about 70 beta testers, there was still the ability to overlay Free42's LCD buffer onto the DM42's screen to check that all was working as expected. Once it was debugged to the developer's satisfaction, that "PIP" facility was removed as it no longer served any purpose.

(12-16-2017 03:49 PM)revwillie Wrote:  You will still see a similar effect though when using agraph or pixel. graphics plotted in the original HP 42 resolution appear in the top of the screen and the stack (depending on how you display the stack) appears below the graphics.

Important bit here underlined.

For those that don't already know, the DM42 has three different screen resolutions: 131x16 (original HP-42S resolution), 200x120 "low" native resolution and 400x240 native resolution. Both of the latter use the whole LCD. The resolution used is controlled by a "virtual variable" (more about that in a second) and the PIXEL, AGRAPH and CLLCD functions have been patched to take advantage of the full screen real estate.

"Virtual variables" are a DM42-specific thing. We needed a way to control the extended hardware that didn't involve adding new functions to Free42 and that would have as little impact as possible on legacy HP-42S programs. We also needed a way of giving programs access to information about the calculator and its configuration, so we came up with the idea of virtual variables. That is my modest contribution to the DM42, so I'm ready for praise and abuse

By putting 0, 2 or 3 (1 is reserved for future use) into X and doing

Code:

STO "GrMod"

You are telling the DM42 to switch to 131x16, 200x120 or 400x240 mode respectively.

Similarly,

Code:

RCL "GrMod"

Returns 0, 2 or 3.

In the same vein,

Code:

RCL "ResY"
RCL "ResX"

Places the current Y resolution in Y and the X resolution in X.

Code:

RCL "Vbat"

gives you the current battery voltage.

Virtual variable "RefLCD" controls how the display is updated during program execution.

These virtual variables don't appear in the variables menu because they don't really exist. Some are read-only, so attempting to store something in a read-only one will just have no effect.