Keld,

I've done lots of bootroms for various cards.  It's one of
those things that was a mystery to me until I actually sat
down and learned it.  Now, it seems so easy :)

The chips you need depend entirely on the card.  Start by
looking at the socket.

If it is a 28-pin, then likely a 27c128 or 27c256 will do the
trick for you.  You'll also have to pick the speed of the
chip.  I try to stick with 150's or faster.  The part number
would usually be something like 27c128-150.  The 27c128 and 27c256
chips seem to be really hard to find. I'm worried that at some
point, they will dissappear from the market completely.

For the rtl8139 based cards that i've used, they either had
a 28-pin or a 32-pin socket.  In both cases, I could use the
27c128 chips.  You just need to insert the 28-pin chip
into the bottom end of the 32-pin socket.  That is, the extra
holes in the socket are at the end where the notch is.

Here's a crude picture:

+------------+--+
|            |  |
|            <  <
|            |  |
+------------+--+
  ^            ^
  |            |
 Chip         Socket

Notice the extra holes in the socket at the right hand side.

For the 3c905 cards, they have a 32-pin DIPP socket.  For those,
I use a flash chip.  The 3Com literature says that only an
Atmel AT29C512 is supported.  The full part number on that
is AT29C512-12PC.

But,  I've used lots of SST Chips for the 3c905.  The full part
number on those is 29EE512-90-4C-PH.  I've heard that the 27c256
will work in the 3c905, but i've never tried it.

The SST chip also works on the Linksys LNE100TX v4 and v5 cards.

There's also another type of socket.  A small almost square chip
that doesn't look anything like the 28 or 32-pin chips.

Those are called PLCC chips.  Some of the Intel eepro100 have
that kind of socket.

For bootrom programmers, I use (and recommend) the eprom
programmer that we sell at DisklessWorkstations.Com.  Now I
know that I am probably biased, cuz I am part owner of the
company, but I really like that programmer.  I've made thousands
of bootroms with it, for over 3 years, and it is a real workhorse.
It will handle many different kinds of chips, including the PLCC's,
with a special adapter.  The only downside with this programmer
is that the software only runs under DOS.

There are lots of other eprom programmers out there as well.
Some in the neighborhood of $100, and others over $1000.  Just
make sure it supports the type of chip you need.  I'd imagine
they would all support the 27c128 eeprom, and they might support
the flash '29' series chip.

One other thing to look for in a chip is whether it is a one-time
programmable chip, or if it can be erased.
The 29 series chips are flash.  They can be reprogrammed fairly
easily.  The 27 series come in either a plastic package or a
ceramic package.  You can tell the difference, because the ceramic
package has a little glass window on the top that you can use
to expose the chip to ultraviolet light, which will erase it.
That is, the plastic chip is one-time programmable and the
ceramic chip is eraseable.


I hope that information is helpful,

Jim McQuillan
[EMAIL PROTECTED]



On Sat, 30 Mar 2002, Keld Jørn Simonsen wrote:

> Hi!
> 
> Have any of you experience with how to burn PROMs, EEPROMS
> or flash for thin clients? I have got LTSP working
> with a floppy boot, but would like to boot via the 
> network card. Which chips do I use (make and number)?
> 
> I was interested in making a flash prom for at rlt 8139C
> card or 3c905 card. Is this possible and what chip
> should I use? what software?
> 
> Best regards
> keld
> 
> _____________________________________________________________________
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> 

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