It isn't a 56 system board. It is the same system board used in the 9533
with a three slot ISA riser. Note all of the slots on the riser are
black. First hint.
The 9533 uses a MCA socket to connect a riser to. The 9533 is an ISA
bus. What could have been, ISA bus with SCSI... But... perhaps IBM came
to the conclusion that IDE was a better "fit" for the ISA bus than SCSI.
SCSI is more useful to systems that perform better with multi-tasking
and multiple devices.
ISA and two devices, a HDD and a CD, you pretty much maxxed out the
controller.
https://www.ardent-tool.com/9533/#9533Planar
See the 4MB of memory soldered onto the system board?
The op is correct that the 9535 and 9540 are not covered with an
announcement letter...
Alexandros wrote:
https://youtu.be/cSqWeNdeahM?si=biVnvcWpD8lqJgEh
A video of a custom 56 on 35 planner (?)
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