<Does the upgrade significantly hurt the value <of it? Or are the Cromemeco boards equally <valuable? No and sorta. As a pure 8800 it's lower value as it's not complete. The comemeco are later boards but of some value especially if the manuals are with them. The backplane upgrade was common(nearly required!). <I have a pretty good idea of what the Altair <8800 is worth in it's original configuration <but I am in the dark when it has been upgraded. <Does anyone know where I might find an original <Altair 8800 CPU card and 8 slot motherboard. I <have a MITS ram card. The original backplane was 4 slots and real sloppy timing wise due to poor electrical construction. Faster z80s boards did not work reliably in them. The 8800 did not have an 8slot (it was two 4s), MITS never offered one that I know of. Likely the 8 slot was yet another aftermarket item. Allison