About this User Manual
This user manual refers to special features of DM42. Look at the following documentation for
description of basic calculator functionality:
•
HP-42S Owner’s Manual
•
HP-42S Programming Examples and Techniques
•
Free42 Manual
General Information
CPU Speed
CPU speed is 24MHz when running on battery (due to limited battery current) and increases to
80MHz when the USB cable is connected.
IR Printing
Calculator contains IR output and can print on HP 82240B infrared printer.
Internal FAT disk
The calculator has 6MB of internal flash storage formatted as a FAT filesystem that is used for
loading/saving programs and for backing up calculator state. It is accessible as USB disk when
activated via the menu 'File > Activate USB Disk >'.
Internal flash has limited amount of write cycles. While the lifetime with ordinary
usage could be dozens of years, an excessive number of writes will wear the flash
memory much quicker.
Worst case scenario, you would have to replace the flash chip, which is worth less
than $1. If needed, SwissMicros will replace the chip at no cost, but shipping costs
must be covered by the customer.
The datasheet mentions a minimum of 100,000 write cycles, which sounds like a
lot, but any change in the filesystem means overwriting at least part of the file
allocation table, which is stored in a static location.
Calculator comes with pre-filled FAT disk contents. In case the contents of the FAT area is lost it
could be always downloaded from the SwissMicros
DM42 FAT files
page. There is the contents of
individual directories accessible separately or the whole contents of FAT disk can be downloaded as
single zip file
DM42.zip
.
There are several directories with special names on the FAT disk:
1
