Yup. Slackware is a great choice for that machine!
Now, let's get to the problem.
You'll need to setup X correctly. Apparantly, it's using 640x480 or some such silly low resolution.
Let's try to edit this by hand.
you can use joe, or pico to edit the /etc/X11/XF86Config file by hand.
Don't worry, it's not so complicated.
Basically, the driver shouldbe set to Vesa at first. (this should get you at least something workable)
VESA is not the best, you're right -- but it's a sort of catch-all that will at least get X up and running.
The problem we need to fix first, is the resolution.
So here's what we do-- use the command (as root):
to open the Pico text editor which is simple to use -- scroll through, and you'll see all sorts of configuration details to how X Windows is set up.
Find the part that starts with:
Identifier "(current identifier)"
Driver "(whatever it is now)"
Change Driver to vesa (lowercase is important).
The next section should be labeled "Screen"
Make sure Device matches the section above.
Now, on to the resolutions --
The color depth supported by vesa are 8-24, i believe -- however, since you're running on older hardware, let's go ith something conservative like 16.
So uncomment DefaultDepth 16
(That means take the # sign out from in front of it.. conversely, commenting a line out means putting the # in front of the line... commented lines in scripts or configuration files are NOT read by whatever they're meant to be interpreted by)
So uncomment DefaultDepth16 and comment out any other Default depth that is selected.
Below that, it'll tell you what resolutions the default XF86Config File is set to -- these aren't working for your LCD --. You see, most earlier Laptop LCDs are set to work only at one resolution, which is why you're seeing the tiny box in the center.
So, since you said yours is capable of 800x600, let's set it to that.
Under section labelled:
change it to read:
Modes "800x600" "640x480"
Now, save the file with control-o (write out) and then control x to exit the pico editor.
Issue the startx command again, and see what you've got.
The vesa driver is just about the slowest video driver available, but it almost always works. LIke I said, this is just something to get you up and running. Later on, you'll want to fiddle with the Xserver for the specific card youv'e got in your laptop.
You'll notice that Xwindows configuration can be a pain at first, but it's all rather straightforward.
ps- hope this wasnt too hard to follow... I'm writing this at quite a late/early hour