... and U14 (above J2) - MM74HC32N - is a Quad 2-Input OR Gate.
I see a few SN74LS374N there on the main board ... these are basically sets of eight clocked flip-flops; typically used for "driving the bus lines in a bus-organized system"!
OK ... here's another random guess:- it seems to me that U8 is tied to the two main expansion connectors (J5 and J6). I'm wondering if it (U8) is a VIA (Versatile Interface Adaptor); mainly as VIA's used to be popular back in the 1980's (again, the BBC Micro comes to mind). It looks like it may be an Intel device (with forty pins). Could it be the Intel 8255, I wonder?
That's enough for now, as I don't want to be dreaming about this stuff (it's midnight here).
