NP-41 Emulator (may be)

[Chris Chung]

Just a brief update as I am quite busy on other things lately.

I received the next batch of PCBs and had constructed 3 units of NP41s (I had only 3 LCD modules left). There is a missed "Shift" label on the PCB.

With the failures of the prototyping units, I had spent a few days on these and I hope they will be more reliable. I had sent out 2 replacement units to Etienne (his V1 unit was DOA due to poor packaging) and Sylvian.

The new design is more clean and the H/W should be more reliable. However one of the units (my unit) had charge pump failure (part of the LCD module) and I had to re-flow the capacitors twice to fix. I hope it is just cold solder instead of something else failed.

I had make changes to the firmware and now the ROM download and bootloader is reliable.

Here are some updated instructions

NP41s instructions
When you insert new battery, you will be at the test screen. The following keys is used,

• 'SST' key advance character set display.
• '4' toggles the beep test.
• 'CLX' exit setup, enter calculator emulation, may need to press twice.
• Other keys will show key-code, also shows battery voltage on screen.

When you are in calculator mode, and pressed 'ON' to turn unit off / timeout off.
When pressing 'CLX' + 'ON', like HP-41, master clear, "MEMORY LOST".
When pressing 'PRGM' + 'ON', you will be placed at setup mode, which have the following options.

• '7' toggles verbose mode, i.e. show / not show register contents and program listings.
• '8' toggles turbo mode, i.e. 8Mhz versus 16Mhz clock.
• '9' toggles LCD filter mode, i.e. when selected, suppress excessive LCD display updates.
• '4' toggles LCD backlight.
• '5' cycles through LCD contrast settings.
• '6' resets calculator to power-up test screen.
• 'USER' place calculator into boot-loader mode.

Please refer to the NP41 thread in MoHPC for ROM download instructions.

I probably don't have time to make progress this month except to play w/ it on and off to check on reliability.

Attached 2 photos of this new builds.
.. Had to use this share link because I had reached attachment quota. I will figure that out later.