Table of Contents
DM15L Info
Purchase Information
- Date : September 2021
- From : Swiss Micros (direct)
- Price : £95
- Serial : 21350
- New Battery
- July 27th 2022
- July 26th 2024
Firmware
Upgrade firmware on Linux
sudo lpc21isp <firmware_file> /dev/ttyUSB0 115200 12000
bash scripts
just to reduce the typing…. still need to press the hidden reset button to start the flashing and to start the new firmware.
You can have separate scripts for ease of loading different firmware
./lf_flash.sh
#!/bin/bash # FWARE=LF15C_250408.hex lpc21isp $FWARE /dev/ttyUSB0 115200 1200
./dm32_flash.sh
#!/bin/bash # FWARE=DM15_M1B_32.hex lpc21isp $FWARE /dev/ttyUSB0 115200 1200
./dm34_flash.sh
#!/bin/bash # FWARE=DM15_M1B_34.hex lpc21isp $FWARE /dev/ttyUSB0 115200 1200
Upgrade firware on Windows
Serial USB Driver for Windows
Windows Firmware Upload Tool
Swiss Micros Official
Swiss Micros Firmware files
| Date | Serial No. | Firmware | Version | Firmware Files | Comments |
|---|---|---|---|---|---|
| 24/05/22 | 21350 | DM15_M1B | 32 | dm15_m1b_32.zip | Extended User Registers |
| 22/11/23 | 21350 | DM15 | 32 | dm15_32.zip | Standard User Registers |
| 21/12/24 | 21350 | DM15_M1B | 33 | dm15_m1b_33.zip | New 2-line stack and other mods |
| 23/01/26 | 21350 | DM15_M1B | 34 | dm15_m1b_34.hex | Bug fixes to new version |
| ROM | Allocatable registers | RAM base addr. | Initial Memory Status |
|---|---|---|---|
| DM15 (Original ROM) | 64 | 0xc0 | 19 46 0-0 |
| DM15_M80 | 128 | 0x80 | 19 110 0-0 |
| DM15_M1B | 229 | 0x1b | 19 211 0-0 |
LF15C - 3rd Party Firmware
- From HP Forum https://www.hpmuseum.org/forum/thread-20046.html
For more details see LF15C - firmware for the DM15
DESK-15 - 3rd Party Firmware
- From HP Forum https://www.hpmuseum.org/forum/thread-23488.html
- You Tube https://youtu.be/ktrKZzN3wJw
- Github for firmware and brief README guide https://github.com/zooxo/desk15
I'll try it out and write up some details…..
RTC Error
- RTC is not capable of calibration/correction
- RTC appears to continue running even when switching firmware
- LF15C has no ability to display RTC but it the rate appears unaffected by the firmware changes
- Requires that Swiss Micros firmware is loaded in order to check current RTC time
Update January 2026
Using my python Watchcheck
| Date Start | Date Check | Delta | Latest Rate Error | Average Rate Error | Comments |
|---|---|---|---|---|---|
| 23/01/26 | -49.0 | Delta -49.0. New firmware DM15 V34 loaded. New Period | |||
| 23/01/26 | 24/01/26 | -47.0 | +2.1 | +2.1 | After 24 hours |
| 23/01/26 | 26/01/26 | -43.4 | +1.9 | +2.0 | After 3 days |
| 23/01/26 | 27/01/26 | -41.9 | +1.8 | +1.9 | After 4 days. LF15C loaded after time check |
| 23/01/26 | 11/02/26 | -11.2 | +2.0 | +2.0 | After 19 days. DM15_M1B_34 reloaded to check time |
Swiss Micros Info
- Documentation : Online HTML User Manual
- Documentation : PDF Manual
- Product Page : DM15L
HP-15C Owner's Handbooks
Download from https://literature.hpcalc.org/
- HP-15C Owner's Handbook : https://literature.hpcalc.org/community/hp15c-oh-en.pdf
- HP-15C Advanced Functions Handbook : https://literature.hpcalc.org/community/hp15c-afh-en.pdf
DM15L Memory Dumps and Program Listings
- See DM15L Progs
