Compaq Portable HDD question

[TanruNomad]

I have a Compaq Portable Plus (with one FDD and one 10mb HDD). I recently got a 30MB HDD and connected it to the board and when I boot up the computer doesnt recognize the new 30mb HHD or the existing 10MB one. Once I disconnect it, the computer does recognize the 10mb one again. When I run a diognostic, it doesnt recognize it either. Can someone help me understand how to get the computer to recognize it? The new 30mb didnt come with any installation disk or anything and the only 2 floppies I have are DOS 3.2 and a Diagnostic one. Please help!

 

[modem7]

I'm unfamilar with the Compaq Portable Plus, but it is a 1983 clone of the IBM PC, and that tells us a lot about what to expect.

Note that the power supply may not be adequately rated for 2 hard drives.

It will have to be established if the controller supports the particular 30MB drive. If it doesn't, you may be able to get it working at reduced capacity (e.g. 20MB).

Some or multiple of the following may be needed to get your addition fully working:
1. Terminator resistor removed from drive that is located on middle of control cable.
2. Position of drive-select jumper altered on 30MB drive.
3. Low-level format of 30MB drive (followed by FDISK/FORMAT).

What are the make and model numbers of the two hard drives?

What is the make and model number of the hard disk controller?

Does the control cable have a 'twist' in it (as shown at http://members.dodo.com.au/~slappanel555/misc/floppy_vs_hard.jpg), or is there no twist?

 

[TanruNomad]

Thanks for the reply. I can't answer all of your questions, but I can give you some more information. The 30MB hard-drive doesnt have a cord or anything, it just connects directly into a 25pin connection on the board. The HDD is currently on another Compaq Portable 1 I have and it works fine on it. The 2 boards are identical and the only different between the peripherals is the one it works on has 2 FDD connected to 1 controller board and the one it doesnt work on has 1 FDD and 1 built-in HDD (10MB). I think it may be as simple as me not having the right setup disk for these computers. I don't see any manufacturer name on the 30MB HDD, but I have all the specs for it.

 

[modem7]

The 30MB hard-drive doesnt have a cord or anything, it just connects directly into a 25pin connection on the board.

So this sounds very much like a hard drive built onto it's own hard disk controller (the "board" that you refer to). A photo will confirm that for us.

If that's the case, what is probably happening is that when you plug that "board" into the computer, you end up with two 'primary' hard disk controllers in the system, something that the system is not designed for.