PC110

The IBM PalmTop PC110

Serial device configuration

Introduction

Once upon a time there was a ThinkPad 755C. The top of the range model cost many thousands of pounds, and came with lots of goodies. After the novelty wore off, it was deemed necessary by the men in blue suits to develop a successor so 'feature-rich' that it would woo back the customers who were buying from the big C-word and the big T-word. And so it came to pass, that the 755CD did appear, with more toys on it than you could shake a stick at, and with a price tag heavy enough to make any Executive feel special. And lo, the Executives came unto the land of three-letter-acronyms, and did buy the 755CD, yet all was not good. The people of Marketing had forgotten to mention The Gospel According to ISA, and the Executives found out the hard way that they couldn't play with all their toys at once. Being good honourable Executives, they praised the people of Marketing, showering them with riches, then spoke unto the lowly Visionaries Of Support in tones that were harsh.

The PC110 follows similar lines to the 755CD, in that you have more toys than hardware resources available to control them. This particularly affects the serial devices. The setup of serial ports on the PC110 baffles most new users, even me once! You have to realise the trade-offs necessary before you can understand how to use the serial devices such as the internal modem, the infrared port, and the serial port on the port replicator.

Default configuration

To configure your serial devices, enter Easy-Setup by holding down <F1> as you power on the PC110. Click on Config, then Serial, and you will be presented with a panel similar to the following: 

Modem 1

PCMCIA 1

IR 1

Serial 1

Modem 2

PCMCIA 2

IR 2

Serial 2

Disable

Disable

Disable

Disable

 

  
This shows the default setup of the PC110 serial devices - the internal modem is configured as the 1st serial device, and the IR port is configured as the second serial device.

Choosing your own configuration

You can click on the icons to enable or disable devices, but remember that you can only have one first serial device and one second serial device at any time, so disable one to make way for another!

The notation of 1 and 2 refers to the COM port to use rather than the number of such devices installed. There is no facility to set up devices to use COM3 or COM4, so you can potentially have three serial devices installed in the system that cannot be used. Tough. Choose the two you want when you want them :-)

Remember that if you include a PCMCIA selection in the configuration, you won't have to load any PCMCIA drivers to enable a modem you may insert - just boot and start using the serial port! Read BIOS support for PCMCIA devices if this is new to you.

Finally, remember that some device drivers may not be too happy with the fact that devices come and go, and you will most likely have trouble installing drivers when the devices they require are not enabled. Check your setup before you install.

Suggested serial configurations

1) You want to use the internal modem as COM1, and the serial port on the port replicator as COM2.

  

Modem 1

PCMCIA 1

IR 1

Serial 1

Modem 2

PCMCIA 2

IR 2

Serial 2

Disable

Disable

Disable

Disable

 

  
2) You want to use the infrared port as COM1, and a PCMCIA modem as COM2.

  

Modem 1

PCMCIA 1

IR 1

Serial 1

Modem 2

PCMCIA 2

IR 2

Serial 2

Disable

Disable

Disable

Disable

 

  
3) You want to use the infrared port as COM1, and the internal modem as COM2.

  

Modem 1

PCMCIA 1

IR 1

Serial 1

Modem 2

PCMCIA 2

IR 2

Serial 2

Disable

Disable

Disable

Disable

 

  

From these examples I think the other combinations should be easy to work out!

Using PS2 commands to control the serial port configuration

Note that you can use the following functions of the PS2 command to configure the serial devices from a command line; again you should remember to disable one device before trying to assign another to the same COM port.

More information on PS2 commands is given here.

UART considerations

The PC110 has one super I/O controller, which provides the functions of a 16550-compatible UART for the serial ports. Note that this UART can run at a maximum throughput of 115,200 bps, and has two channels only. The configuration changes described above simply map these channels to the three serial output devices on the PC110, or disable them if PCMCIA devices are to be used. The UART compatibility is detected by some operating systems in order to give an indication of the maximum connection speed for an unknown modem - that's why you'll see it configured as a generic 56,600 bps modem at times! This also explains why the internal modem is so compact - it only contains the analogue-to-digital componentry on that little card, and that's what made it relatively easy for the nice folks at T-Zone to produce a modem replacement.
 

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Written by Daniel Basterfield. Images found on the internet. Enjoy!