Date: Thu, 9 Aug 2001 13:27:06 -0700 (PDT)
From: Douglas Mandell
Subject: EPROMS for upgrading DAT drives
To: Ade Rixon

Hello again Ade,

I just thought I'd let you know of a little research I've been doing on
availability of EPROMS to use for upgrading Archive DAT drives.

The version 2.75-15 firmware requires a 2 megabit (128k x 16) EPROM,
150ns access time, in a 44-pin PLCC package.  Unfortunately, these parts
do no seem to be available anymore.  However, there is a larger and
faster (4 megabit, 70ns) part readily available from DigiKey, namely the
Atmel AT27C4096-70JC, which is pin-compatible just as the 2 megabit
parts are compatible with the 1 megabit parts containing version 2.63. 
I just placed an order for a couple of these larger parts, which cost
$7.42 when purchased singly, and I'll let you know how I fare getting
them to retrofit into my Archive DAT drive.

I'll keep you posted as soon as the EPROMs get here.  In other words,
I'm still waiting for my chip to come in :)

--Douglas Mandell


Date: Wed, 29 Aug 2001 10:54:55 -0700 (PDT)
From: Douglas Mandell
Subject: Re: EPROMS for upgrading DAT drives
To: Ade Rixon

Hello Ade,

It took a while but I'm finally getting back to you on the EPROM
programming issue for SGI DAT drives.  Most of the time I was on
vacation and then dealing with other issues-- the programming itself
actually went quite smoothly.

Here's what I did:

Since the new EPROMS are twice as large as the ones they are replacing,
and since the state of the extra high-order address bit is unknown, I
programmed the original code into the chip twice, with the second copy
starting exactly halfway into the chip.  I did this by loading the hex
file into the EPROM programmer and then using the programmer's memory
copy command to copy the data to the other half of the chip's memory
space.  I programmed one EPROM and installed it in the drive.

The new software in the drive does seem to work, but it behaves exactly
the same as the previous version with respect to the wierd problem I'm
having with my Indigo 2.  You may recall that I can start to play audio
from a DAT tape, but as soon as playback starts, the GUI for the player
application freezes.  Audio continues to play until I kill the player
application.  When I have a chance I'll fire up my old Indy, with which
this drive worked fine before, and see if it still works with the new
firmware.  I expect it will.

--Douglas Mandell