The clock speed upgrade was one of the very first Japanese improvements made to the 100/200LX. The system clock of the 100/200LX operates at about 8 MHz. Although it is very low compared to the current desk top PCs, it gives you enough speed and swift response in the Palmtop. However, some Japanese users wanted it even faster. One of the main reasons for this is that the Japanese language environment software requires additional overhead for the display of the complicated Japanese characters, the dictionary look-up and character conversion for each input, or the text processing with the double byte character set. They are a handicap for CPU power. The most simple method to overcome this problem is to make your CPU run faster.
The procedure for making it run faster is relatively easy. You need to disassemble the case, unsolder and remove the system clock crystal from the mother board, solder a new crystal with higher frequency in its place and assemble the case again. Anyone with an adequate soldering skill can do the job. The main issues here are not the soldering skill, but the selection of the crystal and installing the software driver needed to compensate for the change of the system clock.
The SHS crystal developed by Setagaya Haijin Salon.
This is the first and most popular double-speed crystal. Setagaya Haijin Salon is the name of a section in the FMODEM forum in NIFTY-Serve, where the study, implementation and test of the double-rate system clock were conducted. The activities have resulted in a commercial product Clock Upgrade Kit,' which a PC store in Tokyo, called PS/Plaza Wakamatsu, started to market in October 1994.
This crystal is tailor made to meet the circuit of the 100/200LX and has a oscillation frequency of 31.673550 MHz, exactly twice the original frequency of 15.836774 MHz. (The system clock is a half of the crystal frequency) The physical size is different from the original one and designed to easily fit into the limited space of the Palmtop.
The CPU of the 100/200LX is designed to be used with several clock frequencies. The crystal of SHS is made to correspond to its highest frequency. Thus, the CPU can handle the higher frequency easily but there is another problem: the system software of the 100/200LX supports only the normal frequency. Running normal system software with the double-speed crystal will cause the following problems:
the screen is shifted or distorted,
the clock progresses twice the normal speed,
the serial port speed is twice the setting,
the beep sound is higher than normal,
the battery voltage cannot be measured correctly.
To eliminate these problems, you need to install CLKUP31M. a software driver program that compensates for the change in clock speed. To compensate the alarm sound in PIM, you better load playEX =, a alarm enhancement program created by MeW (described further on page 39).
The off-the-shelf 32 MHz crystal
The SHS crystal is a custom made one and thus expensive. Also the availability is only in Tokyo area except by mail order. Due to this situation, some have attempted to use an off-the-shelf 32 MHz crystal that is more easily available and inexpensive. You need to install a different system driver (CU32 .COM) developed by HARUYA, to compensate for the change in clock speed.
In July 1996, in the FHPPC forum, Haruneko published the procedures for the clock upgrade by an off-the-shelf 36 MHz crystal. The driver for this configuration, CLKUP36.SYS, was also developed by HARUYA. This upgrade still has some problems: for example, the fast rate for file transfer via the serial port (57 kbps and 115 kbps) does not work with this clock frequency.
Some studies are under way to replace the crystal with a clock oscillator in the 40 MHz range.
Expansion of the internal RAM
The 100/200LX has 1MB or 2MB of internal RAM. Japanese users were eager to have larger capacity to hold Japanese fonts or room for the EMS memory needed to run the Japanese language environment software effectively.
The 4 Mb add-on RAM board from FTL (Future Technology Laboratories Co.,Ltd.) solved this problem. This board hit the market around September 1995. It uses the 4-layer printed circuit board, with exactly the same form factor as the original 1 Mb daughter board, so it easily fits into your Palmtop. The soldering, assembly, cleaning and tests are conducted with the same rigid guideline as the original, so its long term reliability is assured. A beautiful design with beautiful workmanship. At the time of this development, the mother board of the 200LX was the same for both 1MB and 2MB models. The 2MB 200LX has an additional 1 MB on a "daughter board." The 4 MB add-on RAM replaces this daughter board, giving you a total of 5 MB of internal RAM memory on the 200LX. What complicates the process is that some of the 1 Mb 200LX's have the connector to the daughter and some don't. In addition, some later 2MB 200LXs have all 2MB on the mother board and also don't have the daughter board connector. You don't know until you open up the case.
As such, you ought to have a daughter board connector on the mother board to make the add-on board to work. If you have the necessary connector or not, you cannot tell until you disassemble the case to expose the mother board, since the RAM configuration in the 200LX changed several times. PS/Plaza Wakamatsu, the dealer of the RAM board in Japan, has a service to mount the connector to a mother board without it.
External light for the HP 100/200LX
Card Light for the 100/200LX by KTR. The small box on the back houses batteries and inverter circuit (power supply).
The screen of the 100/200LX is reflective monochrome LCD (liquid crystal display). Color backlit LCD screens are used in most notebook personal computers these days. The HP's non-backlit screen helps give it its long battery life. It is very visible in good lighting conditions, but Japanese users wanted more.
They wanted to use their 100/200LX anywhere, even when the lighting was not so good. In a coffee shop with dim lighting, on the night street, on the bed side before sleeping.
In 1995, an enthusiastic member of the HP 100/200LX user group, known only by his network handle "KTR," found a small map light with an EL (electroluminescence) panel operated by a small battery. He immediately wanted to customize it to better fit the Palmtop and organized a group purchase of customized (oblong) version of this light from the manufacturer. A year later, in September 1996, Device Net Co. started to market this card light for the 200LX as a commercial product.
This external light with an electroluminescence panel connected to a small battery housing. The whole gadget can be attached to the top end of the LCD screen as shown below.
Backlit LCD module
Once this KTR's custom-made external light was completed, several Palmtop users noticed that it was thin and roughly the size of the Palmtop's screen. They began experimenting to see if the Palmtop could be modified to use the EL panel for backlighting. They disassembled the LCD module, carefully removed the reflector sheet with its adhesive layer, inserted the EL panel and reassembled everything. In the initial experiment an external box houses the batteries and inverter. The developers have found a smaller inverter circuit and trying to include the inverter inside the Palmtop's case.
The screen of the 200LX with backlit LCD panel.
The Japanese user community has made several developments of hardware which have become commercial products, such as double-speed crystal upgrade and add-on RAM board. The backlit LCD still has a long way to go before it reaches such stage. We will see what will come out of this interesting activity.
External earphone and speaker
Circuit diagram for adding an earphone jack to the HP Palmtop.
The internal speaker of the HP 100/200LX is fine if used for Appointment Book alarms and simple beeps. But software programs are available that let users play music on the Palmtop. (One such program is LXMIDI =, a software MIDI synthesizer for the 200LX). For such uses, higher quality sound reproduction is desirable. This is why some Japanese users have added an receptacle for an external earphone to the 100/ 200LX. The receptacle generally is situated on the side of the Palmtop with the PC card slot, just below the hinge. The circuit diagram for adding an earphone jack is shown above. You may want to add a filter to kill the base noise (modulation frequency) of LXMIDI, when you use the external earphone.
Optical fiber for infrared connections between Palmtops
The IR (infrared) port of the HP 100/200LX is a very convenient way to transfer data. One drawback is that the two Palmtops must be close to each other for the transfer (a maximum distance of six inches according to the HP Palmtop User's Guide).
Two palmtops connected by plastic light fiber. The bracket that connects the IR fiber to the Palmtop is made by one user in Japan. (Photo courtesy of Michikazu "mkaz" Sakata.)
I bought a plastic optical fiber light guide in a do-it-yourself shop. It was meant to be used in the visible light range for decoration and similar purposes. However, it can be used to conduct infrared light between two Palmtops, if it is not too long. According to one 200LX user, it becomes unstable when the fiber reaches the length of 1 meter. Using at less than 50 cm distance is recommended for 200LX users. The 200LX seemingly has a less powerful IR port than the 100LX, which supported longer fiber cables.
The IR port and backup battery are covered by a small plastic cover (right edge of the Palmtop). Slip this cover off and you notice that the IR port is actually two IR devices (one is for sending and the other is for receiving the IR signal). You need two lengths of the optical fiber (one for each port). You also need a way to hold the ends of the optical fiber in place over the IR devices. I trimmed down two standard erasers until they were the same length and width as the plastic cover and fit snugly into the plastic cover slot. I carefully marked on the eraser the location of each IR device. I removed the erasers, bored two small holes in the eraser and inserted the ends of the fiber optic cables. Notice that one of the IR devices is larger than the other. You have to arrange the fiber optic cables so that the large IR device on one Palmtop is connected to the small one on the other Palmtop. When I want to transfer files between two Palmtops using IR ports, I remove the plastic covers, insert the modified erasers in the cover slots and transfer files (see diagram below).
[Important Note: All of the modifications described above void the HP warranty. You should do the modifications at your own risk.]