DS1742W NVRAM RTC Replacement for SGI Fuel, Tezro, O350


New member
Dec 9, 2020
Hi, some of the forum members suggested I should offer the DS1742W replacements also here at The Bazaar. Besides a local thread where I mentioned its development I mostly used an ebay listing. The fees there are terrible but I suppose they provide a maximum reach. I already made over a hundred of these replacements and so far they have been functioning well (fingers crossed). Its been tested on:
  • SGI Fuel
  • SGI Tezro
  • SGI O350
  • SGI O300
  • SGI Numalink Router
  • Tektronix TDS3000
The price is 45 EUR. Shipping is 5 EUR for economy without tracking. +3 EUR for tracking.


New member
Jun 23, 2022
The replacement seems to work without much extra effort. It takes a replaceable CR2032 battery (not included in package).
On Tezro the Dallas chip is located on the mainboard, above the graphics card and to the right (to the front of the case).

After replacement, one might see red LEDs come up with this error on L1 "No system serial number assigned", and it won't power on.

To resolve that:

1) Use a serial cable and plug it into the "Console" port on the back of the machine
2) On e.g. Linux, use `minicom -D /dev/ttyUSB0` (or any other corresponding serial port)
3) Ctrl+A, P in minicom to open settings, D to set speed to 38400, and Q to re-set to the default serial settings 8N1, Enter to exit
4) In the L1 prompt, press a few Enters to get a shell and set the serial number

serial set PXXXXXXX
serial all

5) Press Enter in console for diagnostics to run
6) After diagnostics, choose "1" (Start system)
7) Ctrl+A, Z to exit Minicom

[1] Serial number (PXXXXXXX) is found on the sticker on the back of the machine.
[2] If in the console you're seeing system login prompt instead of L1, press Ctrl+T to escape into L1, then run "l1" to stay in L1 mode.


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