Seeking info on two PROM chips.

From: Brian Chase <>
Date: Mon Feb 10 10:49:00 2003

On Mon, 10 Feb 2003 wrote:

> 23-xxxEx is a ROM/EPROM part number, so they may well be programmable.
> E8 means they're 128KB, or 1 Megabit. The part numbers you quote are
> listed in Compaq Assisted Services online catalogue at $4 apiece, so
> you might still be able to get them from DEC/HP.
> Is there any type number under the DEC label? Are they brown ceramic
> with a quartz window in the top? If so, they're probably EPROMs, most
> likely 27C1024 (64K x 16 bit). If not, they're probably one-time
> PROMs, or possibly Flash. If they're EPROMs, it's unlikely you
> overwrote them, unless you had them in a programmer.

Peeling back the DEC part# labels, it's clear that they're vanilla,
UV eraseable, EPROMs. They're both TI 27C210A-12; I guess I don't need
to be concerned about having modified them.

So, assuming the console ROMs are fine, that means something critical
has died in my VAXstation 4000 VLC between the short period of time
between powering it down and powering it up again. The diagnostic LEDs
on the back of system indicate the following pattern (where the lower
part represents lit LEDs as 1 and unlit LEDs as 0):

   7654 3210
   1111 1101

At initial power on, all the LEDs are lit "1111 1111", a fraction of a
second later it changes to the "1111 1101" pattern and stays there.

Using the following page, I get some hints about what may be going
wrong <>, but nothing
entirely conclusive as I'm not sure whether the codes for the VS3100
map usefully to those for the VS4000.

Some other suggestions that had been made were to check the SIMMs,
check the power supply, and to check the RTC chip. Fortunately, I can
swap bits between this dead system and another good one that I have.
The power supply works, the SIMMs work, and the RTC chip works.

I'm getting down to the point of it either being some faulty component
or connection on the mainboard, or possibly it /is/ still something with
the console EPROMs, though not for the reason I suspected earlier.
I should be able to swap the EPROMs a little later on today, and then
there's a daughter card which contains a frame buffer, various other
I/O ports, and the halt button. Following that, it's down to checking
individual (mostly surface mounted) components on the main board.

On the bright side, I've a working system which can be used as a
reference. Also, the mainboard on the VS4000/VLC is fairly simple--
at least in that it has few components, though they might not be so
easy to replace.

Received on Mon Feb 10 2003 - 10:49:00 GMT

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