IBM 5150 PC Motherboard Version 2
This motherboard version is marked at A as "64KB-256KB CPU." At B are the rows of RAM chips. In this case all four of the rows of RAM chips are soldered into the motherboard, so this board was manufactured with 256KB of RAM.
The ROM, bus, and connectors look to be unchanged from the version 1 motherboard, though the BASIC ROM is probably different internally to allow for the larger memory. The two sockets at C would contain the 8088 processor and the 8087 floating point arithmetic processor. In this case the 8088 is present but the 8087 is not.
