That stands for "Hard Drive Controller" -- this one includes a FDC (Floppy Drive Controller), two COM (serial) ports, a GAME port, and a Printer (parallel) port.

• At the left: HD cable (IDE), 40 pins
• At the top, left to right:
  • LED connection, 2 pins
  • FD cable connection, 36 pins
  • Game (joystick) connection, 16 pins
  • second COM port connection, 10 pins
• The end connections, top to bottom:
  • the first COM port (DB9 male plug)
  • the printer port (DB25 female socket)

The connector strip at the bottom indicate that this is a 16 bit (ISA) card.

Near the bottom of the card are 8 sets of two jumpers.

• the left four select the IRQ for COMA on the board
• the right four select the IRQ for COMB on the board

But it could be otherwise. You really need the "docs" when things get strange. See the notes below.

Below that is a three pin set which selects the IRQ for the parallel port, shown as 2-3 jumpered.

1 3

• Jumper 1-2 to select IRQ 5
• jumper 2-3 to select IRQ 7

When in doubt, the lines on the card can often be traced. The lower IRQ lines connect on the solder side of the card, on the first (8bit) section of the card. Counting contacts from the screw-down end of the card (the rear of the computer), the IRQ lines are found as follows

• contact 21 -- IRQ line 7
• contact 22 -- IRQ line 6
• contact 23 -- IRQ line 5
• contact 24 -- IRQ line 4
• contact 25 -- IRQ line 3

The IRQ lines normally used for the printer are easy to follow. they lead directly to pin 1 and pin 3 of the above 3-pin jumper block. But IRQ lines for the COM ports are often difficult to follow.

The higher IRQ lines come in on the 16 bit extension part, also at the solder side of the card. Counting, again, from the screw-down end of this section, the IRQ lines are...

• contact 3 -- IRQ line 10
• contact 4 -- IRQ line 11
• contact 5 -- IRQ line 12
• contact 6 -- IRQ line 15
• contact 7 -- IRQ line 14

IRQ 13 is missing because it is used by the FPU, and not by any card.

Inspecting the back of the card reveals (in this instance) that only IRQ line 14 is brought in. We could assume that the HDC uses it, and that there will be no other choice.

At the top, behind the exterior COM port are a set of 8 3-pin jumpers. The board is marked "DIS/EN" above the jumper block. Assume this means "disable", "enable."

The board is marked, below the jumper block:

• printer
• serial
• FDC
• HDC

This is only 4 indications, but there are 8 jumpers. The solution is to try some of the following assumptions..

• Perhaps two jumpers are used for the printer (Lpt1 and Lpt2)
• Perhaps four jumpers are used for the COM ports (Com1 com2 com3 com4)
• Perhaps two jumpers are used for each of the HDC and the FDC.

If you really get stuck, get on the internet and look up the manufacturer, or check out card jumper sources at some of the FTP sites like UIArchive, Garbo, or Simtel.

HOST: Outflux.net, http://www.Outflux.net
URL: http://jnocook.net/user/hdc.htm