Another common question I'm asked is - how do I get an XT hard disk going in a 1512/1640/2086?
Remember that those PC's are an XT class of PC - not an AT. Back in those days hard disks were not supported by the main PC BIOS so there was no need for the concept of setting up hard disk type numbers like we have to do on modern AT class computers. Instead every hard disk came with it's own matched controller card that had a BIOS on board that was just designed to support the single mechanism it was attached to.
In theory you just plug the controller and mechanism into the PC then, at switch on, the XT sees the new HD BIOS ROM and calls it's entry point that then hooks the disk interrupt so that subsequent disk accesses are filtered and any directed towards an HD are taken by the new combination.
As such it really should be a case of being able to plug in and switch on - no setup is required - it should just work. If it doesn't then (because such drives are pretty long in the tooth these days) it's probably because the head actuator or main spindle motor of the mechanism has seized. It could also be that the controller's card edge contacts have oxidized if they haven't been plugged in for years.
Other things to look out for are whether the HD needs a Low level format, FDISKing or just system formatting - try booting from a DOS floppy and accessing C: - if this fails try running FDISK from a floppy and see if it can "see" the HD - if so go on to define an active primary DOS partition. Once the system reboots then use FORMAT C: /S to put the DOS system onto the HD. If even FDISK can't see the drive then fire yup DEBUG and look at al the segement offsets between C000:0000 and EC00:0000 in 0400 increments to see if you can spot something looking like an HD BIOS signature (it'll probably have a "(c)Western Digital" or something like that. If you spotted it at C800:0000 for example then try G=C800:0005 which is normally the entry point to start up the LLF utility. If you are going to perform an LLF remember to write down the entries on the bad track table before starting as you'll probably have to enter these by hand at the end of the LLF process.
Finally in this section on hard disks, here's a question I received together with the answer I gave about upgrading hard disks...
Q: I need to put some type of hard drive in this 1512. Can I put some type of card in the slot to adapt to a hard drive or laptop hard drive or any thing at all.?
A: First let me point out a potential problem - the 1512 was designed 10 years ago and is based on the IBM XT that was designed 12-13 years ago. The XT stopped production in about 1989 - 8 years ago. Therefore, trying to find compatible bits for a computer of that age is going to be difficult.
Having said that, the easiest way people used to add HDs to XT class computers was to use a thing called a "hard card" that combined both a drive mechanism and controller/interface card onto a single unit that plugged into a slot. You might still be able to find one second hand somewehere but beware - It must be an 8-bit (XT compatible) and NOT a 16-bit (AT compatible hard card).
The other way to add a HD is the more traditional way of getting a mechanism that mounts at the front of the unit and connects via a cable that goes into one of the slots but again, be warned, you must find one that is 8 bit. What's more, in the XT days mechanisms and controllers were sold in matched pairs so you must find a matched controller and mech. It is not possible to get a generic interface and a separate mech (like you do these days with IDE).
The last hope is that just as XTs were dying out was when IDE was being first developed so there were some 8 bit IDE cards available for a short time and if you could find one of those then you could add a choice of different IDE drives to it. However the likelihood of finding any suitable drive/controller for all this is going to be very slim after 8-10 years. Perhaps a car boot sale, 2nd hand equipment auction or classified ads in the local paper might be the only place you could find what you need.
Remember that, at the end of the day, that PC is worth about £20 ($30) so it's probably not worth investing too much effort in trying to resurrect it (even if you do most modern software will be unusable on it, for example, it cannot run Windows).