Having made the decision to fit a 3.5" drive to your PCW, the decision has to be made about how to mount it.
Fitting drives internally
The first choice is almost bound to be inside the casing, maybe using a spare
B: drive position, but this isn't very easy, unless you buy a commercially produced
drive designed for the purpose. Such drives are available for most machines,
although getting more expensive as the metalwork becomes harder to get.
The drive mounting cradle from a PCW9512 can be modified to take a 3.5" drive and I'll try to explain, although it will be easier when I get my scanner working. The drive mounting cradle has two parts; an inner and an outer. Cut the outer along each side with a small hacksaw just above the mounting lugs, which effectively leaves you with a shallow tray which can be screwed down into the case as before. Cut the end and top from the inner leaving a |___| section. Fit this section into the tray, open top up, and secure with a couple of short self-tapping screws. Press each side of the section outwards above the sides of the tray at about 45 degrees. (it's only thin aluminium so is not hard to bend) Now bend the sides back to the vertical to take the width of the 3.5" drive (100mm). If you've followed me this far you will be able to put the drive into the 100mm wide section, leaving about a 15mm gap under the drive. If you lay this assembly into your PCW9512 you will be able to ensure that the drive is in the best position for loading discs. It remains now to mark and drill holes at the sides to fix the drive. If you have a spare cradle you have nothing to lose by trying this, but it does need patience and DIY skills.
Fitting drives externally
Commercial suppliers of external drives can supply in a variety of configurations;
with or without power supplies, various switching arrangements, single drives
or double drives. If you can afford it, it's by far the easiest option.
But if you want to go it alone the first thing you need is a suitable box; enclosure is the posh term. When I first thought about fitting drives externally I thought that it would be a doddle; just pop into Maplins or any other electronics supplier and buy a ready-made box to hold the drive. WRONG - as far as I am aware such boxes do not exist as standard, they're all made to order. If you know better please let me know.
The B: drive of my PCW8256 was at one time 5.25". It was a 1.2M drive that formatted to 720K, had its own power supply and was considered the one to have at one time, but when I decided to convert to 3.5" I retained the enclosure, modified the power supply to give only 5 volts and fitted the drive in a floppy drive cradle commonly sold to fit a 3.5" drive into a 5.25" computer bay. It is a little large but suits me very well. From time to time this type of enclosure can be found at car boot sales and the like, often complete with 5.25" drive and power supply. If you're lucky you may even find an external 3.5" drive in a neat case, intended for an Atari or Amiga. These don't usually have a power supply.
If you're starting from scratch you could buy one of the 5.25" to 3.5" adapters mentioned above to house the drive. There is room on the front plate to fit switches or push-button if needed and room inside to house a small voltage regulator circuit (see other files for details). It could be used as is, but it's better to make a cover for it. Depending on your facilities the cover could be made from thin sheet metal, fibreglass or wood.
Unless you buy a drive complete you will find that housing the drive presents as many problems, if not more, than connecting it electronically. I hope that you will find some ideas above to interest you.
Ron King
Email address... ron@king27.freeserve.co.uk