IBM 5162 Prototype ？

[modem7]

Have the BIOS chips on this thing been dumped yet?

Not that I am aware of. Considering that the IBM part numbers (78X7460, 8X7461) are identical to those on the earlier motherboard, the contents are probably identical. Based on the content of other IBM 51xx BIOS ROM's, maybe only the copyright year and checksum byte are different, but I think that when I have seen that, the copyright year on the ROM sticker/label has been updated too.

Any theories about which chipset this board uses?

82C201
82A203
82A204
82A205
82C206

The web page at [here] identifies that set as Intel's "8286 Chip set".

 

[Anonymous Coward]

The chip names on this board seems to correspond to ones found in the C&T CS8220 chipset...except that chipset only has five chips, and this one has six. You forgot to include the 82C202 which is in DIP package. Although not mentioned in the datasheet, I think the 82C206 on this chipset was possibly optional, allowing the use of discrete IRQ and DMA controllers.

https://theretroweb.com/chipset/documentation/cs8220-datasheet-62f900da77051198936540.pdf