CPS-GAMES High Density Floppy Upgrade

If you can't yet afford a hard drive, the next best upgrade to enchance the performance of your ST is probably to install a high density disk drive. This will let you store twice as much information on high density floppy disks

Unfortunately you can't just replace the floppy drive in your ST. You need to add a special board to the ST's motherboard too.

CPS-GAMES have come to the rescue with a all new version of thier custom designed module that works with most ST's from TOS1.4 onwards. It even supports high density external drives too!

The online manual is clear and comprehensive, taking you through every step in detail. There are plenty of images showing clear step-by-step images of what needs to be done.


It needs to double the speed of the disk controller to 16mhz for high density drives to operate properly. This is not a problem since the board has a onbuilt 16mhz lock crystal which takes care of this for you.

Some ST's before TOS1.4 don't support high density drives so a TOS upgrde would be needed. You will also probbly need to upgrade the disk controller too.

Installation does require some soldering. The disk controller needs to be removed to make place for the new controller board. There are a few wires to solder though these are straighforward and colour coded.

The black wire as shown connects to the optional external floppy drive connector. The orange wire connected to the high density select signal of the floppy drive. The white wire solders to the ST's motherboard to provide a drive A:/B: select signal.

Having a external drive can save hours of work should you want to copy your double density disks to a high density disk. The fully automatic switching means you can have a double density disk in the external drive and a high density disk in the internal drive. It makes light work from coping files from disk to disk for backups or to save on disc space.

The external drive needs a small jack socket to be fixed on the rear of the ST's case. this is to provide a high density select signal form the external drive to the ST. It can of course be left compleatly off if you don't fancy drilling holes in your ST's case.

The board fits firmly into place under the internal floppy drive.Since the board takes all the singals direct from the ST's motherboard no software is required to make it work! This is the first upgrade to offer such a automatic feature. CPS-GAMES went though many revisions of the board to make it as easy to use and simple to install. Once installed you can forget about it.

How it works:

The problem with most floppy upgrades is they need software patches or switches to work. The cps-games board watches which disk the ST is about to access. If the internal floppy drive has a high density disk in, the board will automaticly switch into high density mode. Should you have a double density disk in the external drive then the board will switch automaticlly into double density mode.

Benefits :

Since the board doubles the data transfer on high density mode, Applications and games will load and run faster thanks to the faster clock speed of high density modes. Extended formats are also possible with the correct floppy drives fitted.


No software needed:

The board holds a simple but clever design which changes the ST's disk controller instructions to make it function. Most kits require you to modify TOS or install software patches for TOS to work with high density disks. These patches often change the default seek rate to 6ms. This is required since when running in highdensity mode the seek rate halves. If this modification wasn't done the seek rate would go down to as little as 1.5ms and most floppy drives would not function at this speed.

The board keeps a watch on the commands which the ST sends to the floppy controller and when it sees a seek rate command the board jumps into action and changes the command. Since this is compleatly hardware activated the software patches for 6ms are not needed. this gives you the freedom of a fully automatic board which requires no special software to be installed. Its a simple "Set and forget" type solution.



Professional quality - External drive support - No software required - cheaper than most other kits.



Requires some soldering - older machines need TOS upgrade.






£50 for full kit assembled and tested. Includes internal drive.

Other variations of the kit are also avaliable.