Resurrecting an HP 200LX (or 100LX, 1000CX) that was unused for a long time

Recently (January 2018) I was asked by a former 200LX user by email, how to resurrect a 200LX that might have upgrades in it (maybe a RAM upgrade, maybe doublespeed). The user could not remember how to get it to life again with all its hardware components and asked me to guide him.

I did, and I thought this might help others, too, so I share that text here with all who might be interested in resurrecting their ancient marvel.

Here is what I wrote to him:

Always remember to put main batteries in first, backup battery second. Because the backup battery will be used to power the RAM as soon as there are no main batteries inserted. Always use a fresh backup battery (CR2032 Lithium coin cell) with negative pole facing upwards.
After inserting main batteries, the Palmtop should boot into the Application manager. If it doesn't, check, if there is a PCMCIA card inserted. If there is a card inserted and it contains a config.sys, the boot procedure will use the config.sys from the card and the system may not boot up as expected.

First, there is the self test  implemented in the BIOS (start it with switching the Palmtop on using the keyboard combo ESC-On). That test routine is able to detect the amount of installed RAM, EXCEPT if there is a larger memory upgrade installed. Those larger upgrades were not addressable using the standard address lines of the processor, but needed 1 or 2 additional I/O lines of the processor so they could be addressed, hence they needed a special software driver to be available in any way to the system. Everything up to 4MB was addressable directly and would be detected by the self-test. 8MB upgrades were either "natively" addresed or only accessible via additional lines (i.e. needing a driver) and everything larger than 8MB was, IIRC, only accessible using a driver.
Hence, if the self-test tells you that there are 1MB or 2MB installed, it doesn't mean that there isn't maybe a, 8, 32, 64 or 96MB RAM upgrade installed. ;-)

If it says "4MB" or "8MB", there are only 4MB or 8MB installed, as 2MB of the 4MB are located on a daughterboard, and there cannot be two daughterboards installed. RAM upgrades always come on a daughterboard, except some(!) 8MB upgrades, which were soldered directly onto the mainboard.

If the power-on self test isn't readable, i.e. the letters are blurred, mixed up, shifted or something like that, there is a speed upgrade installed. The speed upgrade blurs the screen on most devices and needs a software driver ("doublespeed driver") to make all affected parts of the system work normal again. Affected are: Screen readability, frequency of beep sounds from the speaker, the serial port (baud rate is approximately doubled and won't sync well with the peer), function of some PCMCIA cards. Also the overall system speed is affected, but that's the wanted effect, which is not reverted by the driver. All software runs double as fast as before.

However, if the screen of the self-test is readable, it doesn't necessarily mean there is no speed upgrade installed. As I said above: Readability is only affected on most, not all devices. You can check presence of a doublespeed upgrade in the "timer" item of the self-test. It will report "Not OK", if a speed upgrade is installed.

I have packed a bunch of drivers for some speed and RAM upgrades as well as the backlight upgrade into ZIP files that you can use as CF card images: Simply unzip, put the contents into the root of a compatible CF or flash card, put the card into the slot and power on the Palmtop so that it boots. This will go into a driver installation routine, which will try to make a good job detecting what hardware is installed. Not fail-safe, but a little help maybe.

Please drop me a line, if you need such a card image.

Remember that if you have a larger memory upgrade that creates an additional drive in DOS, you will need to swap drives C: and F: (or at least you *should* do that, so that standard software saves its stuff on the larger drive). That also means, that the config.sys loading the RAM upgrade driver (and doublespeed driver, if applicable), needs to be installed on the small native drive, and a small autoexec.bat that swaps the drives also resides there, but another autoexec.bat that's executed afterwards needs to reside on the larger drive. The one on the smaller drive passes control over to the one on the larger drive after swapping drives, if I remember correctly.

In case you want to resurrect a doublespeed LX and need to transfer the doublespeed driver via serial port to the Palmtop before you can install it, there is a method to make the serial port work normally even without the driver. I quote here the sectoin from the Times2Tech doublespeed driver documentation, that describes that method:

Note: All keys within <> are referencing a single key on the palmtop keyboard.

We realize that some palmtop screens are extremely hard to read when the speed upgrade driver isn't running, so you may have to work blindly when entering the debug scripts below. It is best to start from the DOS prompt outside of System Manager and not from a DOS shell within System Manager.  To exit System Manager do the following key sequence: 

<&...><MENU>AT<ENTER>

This DEBUG script temporarily fixes the screen and totally restores the use of the serial port: 

   DEBUG 
   A 
   MOV AL,1E 
   OUT 22,AL 
   MOV AL,FD 
   OUT 23,AL 
   MOV AL,21 
   OUT 22,AL 
   MOV AL,01 
   OUT 23,AL 
   RET 
   <ENTER> 
   G 
   Q 

You can also try to set your baud rate to be half of what the PC is using and you should be able to transfer files as well, but this method is not guaranteed to work.

Also check all the other articles about the HPLX Palmtops: View all HP Palmtop Articles. They might also give you hints for your procedure of resurrecting your Palmtop!