XF551 with Nothing in U6

[pixelmischief]

I have an XF551 that's been working fine for years.  I recently bought a HyperFX upgrade for it and when I opened it up...there was nothing in U6.  Just through-holes filled with solder.  With nothing to remove, I just installed the upgrade.  The drive still woks, but none of the expected functionality seems available; no ultra-speed skew in SDX format and no "boot?" prompt when I power on without a disk.  I opened one of my other XF's and it is as I would expect; a socket at U6 with a ROM in it.

 

I suppose I can desolder the upgrade from the "brainless" (two-brained?) XF and put it into the socketed one, but I'm still curious about the unexpected configuration.  A lazy Google shot turned up nothing.

Edited September 2, 2023 by pixelmischief

[cwc]

If I am getting this right from another thread (happy to be corrected), the firmware on your XF551 without U6 will be on the P8050H processor U1. I assume you can install a socket and EPROM in U6 (as you have done) then change the jumper from the S3 to S4 position and that should do it.

 

See: https://forums.atariage.com/topic/338300-atari-xf-551-roms/?do=findComment&comment=5308127

Edited September 2, 2023 by cwc

[pixelmischief]

@cwc Thanks for info.  Decided to just remove the mod from C6 and put it into the socketed XF, since it requires no additional mod.  Got the "boot?" prompt.  Now I just need to learn about these many "modes".

[cwc]

In case you haven't found the manual: http://blog.3b2.sk/igi/post/Hyper2b-XF-10-MANUAL.aspx

Edited September 3, 2023 by cwc