Epson EQUITY 386/33 PLUS - Manual (Page 72)

Slots 1 through 3 are designed for 16-bit option cards and slot 4
is designed for an 8-bit card. As you can see below, a 16-bit
card has an extra connector along the bottom.
M-bit card 8-bit card
Usually it does not matter which slot an option card occupies as
long as the card fits in the slot. For example, you can place
some B-bit cards in a 16-bit slot. However, you must follow
these guidelines when deciding which slot to use:
An 8-bit card with an additional tab along the bottom must
go into an S-bit slot.
If you install a disk drive controller card, place the card as
close as possible to the drive it is controlling.
Some option cards must be installed in a specific slot.
Consult the instructions that come with the card to see if
this is the case.
Note
If you are installing a high-resolution graphics adapter card,
follow the instructions below to install the adapter card; then
see “Using the Alternate VGA Interface” on page 4-16 to
connect the card to the alternate VGA interface in your
computer.
4-12 Installing and Removing Options