|J1 50 pin header
JP1 Unk Unpopulated
JP2 Unk, unpopulated
JP3 Bottom two pads shunted.
P1 DB25 port
P2 solder pads for 50 positions
|RN1-3 Resistor Networks
U11 AMD DP8303N
U15 NS DM74LS240N Oops, logic.
U18 Chips P82C612
No oscillator, clock might be generated by Chips P82C612...
J1 outline hints at a previous configuration of a right angle socket
with retentive catches.
P2 has the solder pads for 50 positions, while P1 is a DB25. Maybe
there was a different external port?