XU1 is an 74F74 dual D-type flip flop (sic) although it may not read exactly that on the chip (on my 1D.4 it's a Philips 74F320), but functionally it would be the same.
According to the schematics:
"OOPS! All this stuff serves to correct one minor Gayle bug and a number of Alice deficiencies not yet corrected. Assuming the changes are implemented in the production Gayle chip, then all this silliness is best erased"
Your 'weird' board seems perfectly configured to accept the revised bug-free Gayle chip, of course this was never produced so it still has the standard one.
New Gayle:
XU1 = empty, XJ1 = 0 Ohm bridge
XU2 = empty, XJ2 = 0 Ohm bridge
XU3 = empty, XJ3 = 0 Ohm bridge
XJ4 = empty (bottom-left corner of Alice)
U26 =74LS86, U26X = empty (on the left of floppy+LED connectors)
...aka exactly as on your board. So either they forgot to implement the corrections, or for some reason your specific Gayle behaved bug-free and the fixes were not required
ever had any problems with this board?
According to the schematics:
"OOPS! All this stuff serves to correct one minor Gayle bug and a number of Alice deficiencies not yet corrected. Assuming the changes are implemented in the production Gayle chip, then all this silliness is best erased"
Your 'weird' board seems perfectly configured to accept the revised bug-free Gayle chip, of course this was never produced so it still has the standard one.
New Gayle:
XU1 = empty, XJ1 = 0 Ohm bridge
XU2 = empty, XJ2 = 0 Ohm bridge
XU3 = empty, XJ3 = 0 Ohm bridge
XJ4 = empty (bottom-left corner of Alice)
U26 =74LS86, U26X = empty (on the left of floppy+LED connectors)
...aka exactly as on your board. So either they forgot to implement the corrections, or for some reason your specific Gayle behaved bug-free and the fixes were not required
ever had any problems with this board?
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