Replacing an FM Towns II CMOS Battery

This isn’t something I was originally planning to write about but after all the recent posts on fixing up the FM Towns I thought I may as well finish the story off. I’ve found so little information when Googling, I’ll try to spare someone else the trial and error I’ve gone through.

At any rate, shortly after finishing a long awaited playthrough of Wing Commander, I decided it was about time to sort out the dead CMOS battery on my FM Towns II UR. I had no idea where the battery was located or how to take the machine apart which is where this guide comes in. Most of these photos were more for my reference than anything else and not with this purpose in mind so bear with the quality.

Taking the back of the case off is easy enough. Just undo the 4 screws + remove the memory slot flap and the back of the case will slide straight off. This just presents you with a second inner case of steel panels, the top of which needs to be removed by undoing the many, many screws holding it in place.


That will expose the built in monitor and the various boards surrounding it. Hopefully this goes without saying but CRT screens act like giant capacitors and are more than capable of giving out lethal electric shocks. You either want to discharge the tube or be extremely careful not to touch it. The good news is that you don’t need to go near this part of the system much so the latter should be fine. The computer part of the unit is on a separate caddy that can be slid out of the back once unscrewed.


Before sliding this out, you will need to unplug the monitor cable at the front left, the speaker cable at the front right, a connector cable at the back right and another at the top left of the case (the grey three pin plug in the photo above). It should be obvious which cables once you start sliding the unit out.


Having got this far, you need to remove the fan at the back of the case so that you can then remove the board it is attached to. You can unscrew the fan through the metal grill. There is nothing attached to the circuit board at the bottom, it just needs unplugging, unscrewing and lifting out.


Since I had no idea where the CMOS battery was, I continued stripping parts after this. A lot of these clip into place on the plastic frame so you simply have to pry the plastic clips open to release. It’s quite a neat design but doesn’t exactly give easy access to the motherboard since it’s at the bottom.


I was expecting the CMOS battery to be attached to the motherboard and that I would need to strip everything right down to that level. As it happens, I could have stopped earlier. Just below where the fan was is a little space with a black plastic tab over the top. The CMOS battery is hiding just underneath the tab. It’s attached to the motherboard via a plug and short wires so you can easily remove it.


The metal plates at the ends of the wires are firmly attached to the old battery. I pried these off as far as they would go, snipped off the remainder and soldered what was left to a new battery. Soldering to batteries isn’t exactly the best of ideas but it does the job. It’s a CR2450 battery you need if you want an exact replacement. I wrapped this up in tape and started the rebuild.

Once I had the machine back in one piece, I endured a lot more messing around before I was sure my fix had worked. I’ve been using Towns OS to set up my hard drive each time I started the PC. I still found the settings weren’t being saved if I powered off. The clock on the other hand was now keeping time so I knew my battery was working. I had the idea that maybe there was a second battery in the unit for a while but it turns out that all I needed was to use a DOS boot disk, with the setup2 program (as described in a previous post) to set up the hard disk. This then saved the CMOS settings correctly.

Installing Towns OS is nice and easy. There is a utils folder on the towns CD with an install program (it’s the icon with HD and an arrow). I did find out that this wiped my hard disk after I’d done it. Not a big deal but I won’t be importing my Wing Commander pilot into Secret Missions as a result. I had been planning on doing a video showing the last mission but I’ll do the last mission of Secret Missions II instead (when I make it that far).

Wing Commander 1 FM Towns (First Look)

I’ve been gathering old computers a good number of years now and had managed to get near enough all of the one’s I really want with one exception. The FM Towns was a Japanese PC variant which came out in 1989. It was a 32-bit machine with 640×480 SVGA like graphics, 2Mb of RAM, 8 channel music + 6 channel PCM, built-in CD-ROM, sprite hardware and was basically years ahead of anything here in the UK where I was either still using a 48K ZX Spectrum or just getting my first 8Mhz CGA PC. The name apparently comes from the Nobel physics prize winner Charles Townes but the spelling was changed to make sure people pronounced it correctly. The FM stands for Fujitsu Micro.

As a massive fan of DOS era PC games, the FM Towns is particularly intriguing as it got enhanced ports of many familiar titles of the era. Most famously, several Lucasarts/Lucasfilm Games adventures and the Ultima series. I’ve emulated some of these in the past but I’m far more into real hardware so I decided it was about time I spent some of that pay rise and got myself one of these:-

IMG_20170528_072618 (1)

This is an FM Towns II UR which is a 486SX, with 2Mb of RAM, a pair of 3.5 inch floppies up the front and a really tiny (about 8″) but extremely sharp built-in monitor. Allegedly a few FM Towns did make their way to the UK but the only realistic way of getting one of these is to import it from Japan. They aren’t cheap and they definitely aren’t light so this is one for the real “enthusiasts” only. The power supply over there is only 100V so it needs a transformer to work in the UK. The one I’ve used on my machines from the USA is 110V (presumably deliberately in the middle of the two standards) and this seems to work fine.


Round the back are some expansion slots, monitor in/out sockets RS & printer ports and most importantly from my point of view a SCSI port for adding an external drive. FM Towns machines didn’t usually come with a hard drive and needed to boot the operating system from a CD. With just 2Mb of RAM as standard, that doesn’t leave much room to play with and from what I’m seeing, a hard drive is a near essential extra as we’ll see shortly.


The keyboard has some interesting keys that I’m not used to including an extra 8 function keys and a ‘000’ key. I can’t say I’m a fan of having extra keys directly below the spacebar but I won’t be doing a lot of typing on this. The mouse is taken from an MSX which has compatible controllers and the gamepad is a fairly simple affair that I’ll probably ignore in favour of keyboard whenever given the opportunity.


It’s high time to play a game on here and what better to start with than Wing Commander. The FM Towns release comes with some fancy new artwork for the cover and features CD audio, cockpit speech (in Japanese) and digitised sound effects throughout. On starting it up, however I was greeted with stony silence which was something of a let down. From reading through the installation sheet that comes with the game I gather that on 2Mb machines that are running the game from CD, it defaults to no audio to stop the gameplay getting interrupted. It is possible to switch them back on by pressing ‘M’ for music once you start the game. The sound can’t be turned on until you are in the cockpit with ‘S’ to turn on speech and ‘Ctrl + S’ to turn on the sound effects. The reason for these being off is readily apparent as the game constantly loads off the CD and the music and gameplay grind to a halt every time it does it. I recorded a quick and dirty video playing through the first mission below which will give you an idea of what this runs like on a stock FM Towns. Expect a whole lot of loading from that single speed CD drive:-

The music and sound effects are fantastic. I especially like the crescendo at the end of the briefing but the effect is slightly ruined when the next scene has to load. From what I’m seeing, this could well be the best version of WC1 but the loading times and constant pauses are jarring to say the least. It clearly needs that hard disk so I’ve ordered a cheap refurbished 2Gb IBM laptop hard disk + a 50-68 pin SCSI cable off Ebay. I’m hoping that I can more or less just plug that in and be good to go but I can’t profess to knowing anything at all about SCSI drives or installing them in obscure Japanese computers. I’m also looking into memory expansion. The Towns uses a standard 72pin SIMM (non parity, non EDO) so if I chuck in an 8Mb chip it should in theory greatly reduce the need to load data all the time.

Much like the Turbo button on old PC’s, the Towns has two modes with the slower being compatible with the original machine (386SX). I did try running Wing Commander in fast mode (hold down T at boot) but it clearly ran too quickly and slow mode is the way to go. Other games I’ve tried like Ultima Underworld and Alone in the Dark benefit greatly from the extra speed of fast mode. Alone in the Dark actually caches screens to floppy disk when playing the intro in order to not stop the CD music. When you are using a floppy drive as virtual memory, I think it’s a clear sign that you need a hard disk.

The Ultima games on the other hand are much less demanding and run fine without the hard disk, even the famous Ultima 6 talkie version. Underworld I would have benefitted but didn’t run too badly. Underworld II actually requires a hard disk to run at all although it doesn’t appear to mention this on the outside on the box, only when you read the setup instructions. I’ll play through some of these properly when I get the chance.

For now, and pretty much as ever when buying an old machine like this, I need to throw a bit more money at it. Compared to the IIGS which was a serious money pit, I may have got off lightly this time. I’ll wait for all the bits to arrive and then see if I can take a proper look at Wing Commander.