3458 A5 board... what is U102, the 8pin DIP?

[acts238willy]

In the xdevs 3458 teardown/repair post, I noticed that the 'new' short SMT A5 board still has an
8 pin DIP in a socket... U102.  What's with that? They couldn't roll it into one of the ASICs?  I only
have the long boards in my 3458s and there doesn't seem to be a similar PDIP.

What does U102 do in the new short A5 board?

[bsdphk]

It holds the configuration bits for the FPGA

[ScoobyDoo]

The PROM configures the FPGA and one version supports 3458A option -001
In such case extra address lines are configured which activate extra memory option -001

[acts238willy]

So if the 8 pin PROM is left out, does the whole board stop, due to lack of instructions..
OR
Does the A5 board operate fine, just not having option 001?

[martinr33]

No FPGA bits means that the board won't work.

There are two different versions of the short board, and for some reason they use different configuration EEPROMs. You can buy the memory upgrade for the later version for somewhere around $30, but the EEPROM for the earlier boards is not available.

Strangely, the new version of  the board with upgraded memory was cheaper than the non-upgraded version, but that appears to have changed as both versions map to a lead-free replacement - which is what I would guess is in the black machine:
https://www.keysight.com/my/partDetail/03458-66675


Upgrade chip:
https://www.keysight.com/my/partDetail/03458-88810

There's also an LF ADC listed, but only for factory upgrade.
https://www.keysight.com/my/partDetail/03458-66523

[ScoobyDoo]

Hello

          The PROM configures the FPGA and needs to be installed - otherwise the FPGA content is empty
          There have been two versions of the A5 board (using the yellow STM SNAPHAT batteries), there is an ERC label on your board as legend.
          The older A5 boards used one of the (03458-88807/03458-88808) and the later boards (03458-88809/03458-88810) ODD = basic / EVEN = -001 option
     
          The earlier A5 boards needed  (undocumented) 03458-88808 PROM as -001 upgrade - the more recent boards use listed 03458-88810 (online available)
          Which one you need depends upon ERC number of your board (& S/N unit) and KS Loveland USA most likely can help you with 03458-88808 if you provide
          them correct info of your unit (ERC label + S/N°). This is also only difference between a standard unit and unit with -001 memory option.
          It is recommended to contact your regional KS service center or KS Loveland USA to guide You to identify and order correct part ...
          The part itself cost less than 30€ (USD) and comes with a label that you should glue on the board to notify service engineer it has been upgraded.