Re: Enhancing my UDBs

Eric Smith (
7 Nov 1996 21:23:08 -0000

"Wang, Philip (NJAOST)" <> wrote:
> (to use ISDN on UDB)
> - I was told the external ISDN device I am using is like an router,
> which is connected to my PC's ethernet port right now. I wonder if I use
> an ethernet hub connecting multiple UDBs and PCs to the hub and then
> from hub connecting to ISDN line I can wire all my computer devices to
> the world with a 128K line. The question is: Does Linux on UDB/alpha has
> good ISDN support? Will this method work?

If your "external ISDN device" is really a router, things will work fine.
You don't need any Linux ISDN support for that.

However, if the device is a low end bridge, or a deliberately crippled low-end
router than can only handle a single host, you'll have trouble. In that case
you may want to set up IP masquerading, so that one box will hide all of the

Also, if your ISP only gives you a single IP address you will need IP

> (to add more memory to UDBs)
> - How much memory needed for UDB running Linux? I have 24mb each now.

24 MB is tight on the earlier a.out distributions (e.g. Red Hat up through
release 3.0.3), and you may have lots of swapping. Elf distributions (e.g.
Red Hat 4.0) use shared libraries so the memory footprint is smaller.

Usually 24 MB on a 166 MHz UDB consists of a pair of 8 MB SIMMs and a pair
of 4 MB SIMMs. To expand the memory you will have to replace at least one

On a 233 MHz UDB, they usually used a pair of special 12 MB SIMMs, which
will only work in the UDB in the first pair of SIMM sockets. This leaves
one pair of sockets available.

Memory for the UDB *must* be true 36-bit memory. 32-bit memory won't work,
and neither will "logic parity" memory.


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