43s status

[Martin Hepperle]

Dear All,

allow me to throw some ideas into the pond to see whether they float...

While I am sure that you have discussed already zillions of possibilities I would like to share some ideas for an "XP 43S pocket calculator and tinkering assistant". Maybe some of them can be picked up and integrated easily without much extra effort. The main idea is extending the basic calculator to something more useful and versatile without making it bulky and expensive.

Keyboard

• two layers with labels in between instead of double shot injection molding:
• 0.5-1.0 mm clear Plexiglas or Lexan planar face plate with laser cut holes for keys
• top key layer: 0.5mm vacuum formed clear Plexiglas or Lexan, laser-cut with main hinges at bottom of keys left standing (durability?)
• bottom key layer: 0.5mm vacuum formed black Plexiglas with thinner hinges at bottom and labels by stickers or "tampon printing"
• low profile micro click switches as SMD parts soldered to main board
• the clear top layer protects the key labels and serves as the main hinge.
  Laser cutting is affordable, but I am not sure whether they can handle such thin Plexiglas or Lexan.
  

I saw that there seems to be a patent by C. de B. covering this idea, but for a hobby DIY product one could implement this idea without problems.

Note: not everything of the following must be directly available in the first cast of the operating system, but the hardware should be available to add such extensions to the software later and ther software should be prepared not to block future functionality.

Mechanical Design
Provide means to attach external extension boxes to the case, e.g. by screws in prepared screw holes or hooks.
Extension modules offer the possibility for the user to compose pice by piece what he needs.
Extensibility was a major advantage of the HP-41 and the Hp-48 systems.
On the other hand these systems, especially the HP 48, family suffered somewhat from the volume provided to install internal extensions.
The basic machine should be small and handy and not provide empty space, slots etc. for extensions.
Extensions could be part of a sliding cover, which could be easily replaced.
E.g. on the HP 20b and 30b the rear cover could be replaced by a double height cover with extension modules inside.
All mechanical and electrical connectors would be under this cover.
This would be a similar concept like the shields stacked onto an Arduino board, only more elegant and sleek.

Interfaces

• Color display with (software) switchable backlight, capable of Unicode text as well as graphics output
• keyboard
• programmable low current consumption configurations (clock speed, display off), to allow for long term tasks (alarms, in situ measurements)
• internal LiPo battery of high capacity (4+ hrs. run time at full speed)
• serial interface instead of direct USB, can be used transparently with USB-serial cable for data exchange with PC but also for general serial connections like GPS etc.
  A WP 34S with built in USB board is fine, but I cannot connect serial devices like many GPS boards to it.
  Keeping the serial-USB converter as an external not built-in component (or cable) like on the HP 48/49 provides more flexibility but the same level of comfort because the user does not see a difference whether the USB-serial converter is in the cable or in the computer.
• optional
  • serial Bluetooth link instead of serial (if power consumption is not too high)
  • touch screen for some functions (like HP Prime)
  • charging via induction loop instead of wires?
    
• additional interfaces for tinkering (see popularity of Arduino, Raspberry). This might attract more potential customers than the few die-hard calculator fans
  • 1 A/D and 1 D/A interfaces for direct measurements, resolution at least 10 bit (plus assorted commands)
  • 4-8 digital I/O pins for simple control tasks and for I2C, TWI and SPI communication for easy interfacing with sensors (plus assorted commands for I2C, SPI, TWI)
  • of course GND pin(s)
  • infra-red for remote control and printing (is IrDA obsolete? I would prefer Bluetooth or 2.4 GHz or 433 MHz link, but low power consumption)
  • pins for external power supply to calculator for long term operation
  • optional: pins to supply (low) power from calculator to external devices (e.g. 3.3V, 5V) for external sensors (e.g. thermometer, accelerometer)
  • all these using a standard connector, avoid any special connectors.
    

Martin