Another Newbie Question

[Duane Attaway]

On Tue, 29 Oct 2002, rod holcomb wrote:

> 386SX 16 MHz, 2 Meg ram (easily upgradeable to 10 Meg) , 40 Meg HD,
> floppy, 1 serial, 1 parallel, 1 ps/2 mouse ports, black and white LCD
> display other information:
> Micro Channel arch. 
> A rear slot (looks like a docking station port) for “Attaching and
> Detaching the Communications Cartridge… It supports the following
> half-size Micro Channel communication cards.
> IBM 3270 Connection
> IBM System 36/38 Workstation Emulation Adapter/A
> IBM Token-Ring Network Adapter/A.
> 
> Also on the side of the laptop is the “Communication Interface
> Connector” for installing a “modem or serial adaptor” I’ve never seen a
> slot like this: about .75 in tall 1.5 inch wide 4 inches deep.

Does IBM still sell tokens if I lost one?  ;)

> The main task I envision for this machine is as a dumb terminal.

I've done little as 4MB with a 386 from a slack floppy.

> Can I find any expansion cards that would allow me to connect to my home
> Ethernet?  Is this cost prohibitive?

There are parallel port ethernet cards, known as pocket and portable
ethernet adaptors.  You can find a list of supported cards in the kernel
under Network Device Support ->Ethernet (10 or 100Mbit)  ---> Pocket and
portable adapters.

> How far can I get a serial connections to travel.

Most people have no problems with 50 feet through the serial cable.  Some
people claim up to 500 feet.  The serial port uses a simple technology of
positive and negative 12 volts swinging between the two ranges for a logic
level.  For a long line of untwisted or unshielded wire, reflections of
voltage spikes really hit the other side hard and can often create bit
errors.  At higher baudrates, the slew rate makes the waveform look more
triangular than square.

Best bet is to start out with low rates and work up.  The UART chips have
clock rates that are very programmable.  With a simple clock divisor
trick, you can double the "maximum" of 115,200 baud.  An oscilloscope
might come in handy if you want to push the limits.

man setserial <---has the exotic information.

> Should I bother installing Linux or get just get a terminal program to
> run from DOS and continue to use the WP5.1 that is on the machine.  ( I
> already installed VIM for dos but I don’t like using it for prose.)

DOS programs may be much more compact since they aren't designed as
multi-user operating systems.  640KB in DOS should be enough for anyone...