🚀 go-pugleaf

>our group is considering the purchase of several laptops
>... basic characteristics: active matrix display, 500+ Mb 
>hard disk, 486 DX4 75+ MHz, 16Mb RAM ... to run X windows
>... and ... to connect to our UNIX systems via external 
>(probably) ISDN modems.

Well, if you are just talking about running a decent X11R5
server, your processor, ram, and hard drive space are just
fine.  Moreover, for most X applications which can be done
reasonably well over a dialup link, the absence of serious
hardware acceleration in your display system will not kill
this application. Frankly, SCO UNIX and X11 can be run on
a "properly tuned" 386-33, 8 mb ram, 200 mb hard disk box
with more or less completely unaccelerated ET-4000 video
card -- this configuration doesn't lack any noticable kind
of responsiveness on a direct 10BaseT ethernet (100KBPS+).

Unfortunately, I've not visited many hotel rooms, company
guest houses, or homes with 56KBPS or 112KBPS ISDN jacks.
The main advantage of notebook system (portability) might
disappear if you tie yourelf to ISDN tranport.  With good
quality modems you get 14.4KBPS (and sometimes 28.8KBPS)
on analog dialup.  Moreover, with hardware compression a
virtual X11 data stream will actually transport a bit more
quickly over the 14.4KBPS link.  I wouldn't count on going
much faster on a hotel (or company guest office/residence)
telephone jack.  X11 Xterm is tolerable at this speed; and
things wih static displays like netscape main windows will
work just fine -- don't try to do animation or remote CAD.

>Aside from the pitifully small screen, are there any 
>counterindications to using these machines as X terminals?

Yes -- get it in writing that the specific model and serial
port you want to use will perform as expected.  My Thinkpad
750Cs has slow (19.2KBPS) 8250 UARTS (not the fast [114KBPS] 
16550AF UARTS) on the stock serial ports.  IBM's high speed
data/fax modem PCMCIA card has an on board 16550AF -- but an
external 28.8 modem will not be able to transmit 28.8 KBPS
(much less a virtual compressed data stream which may peak
at 114KBPS) through the serial port on IBM Thinkpad 750Cs.

The small screen is OK.  You can do decent X11 work on 640
x480 pixel screen.  Some X servers also offer the option of
rolling this 640x480 window around in a 1024x768 virtual
screen space -- the video is not the serious limitation.

AJ Annala