FM Towns details

Fujitsu Micro Towns family of Hyper Media Personal Computers has several branches and people looking to buy one of those machines are often left wondering what to choose, and is it worth the price.

General info:

There are 4 major FM Towns groups:

  • Grey tower models (generations 1-4, all are 386DX @ 16MHz)
  • Grey desktops (386 and 486 chips with different clocks)
  • All-in-one models (CRT monitor is part of the body, 386SX and 486SX chips)
  • White desktops (486SX and DX2, some early Pentiums)

Then there’s Marty gaming console, which – performance wise – is like all-in-one UX but cannot have it’s memory expanded.

The Towns started as a 386DX machine running at 16MHz. While it uses a custom DOS kernel, and can have its own version of DOS and Windows installed, it’s not a PC. The most common mistake that people make when trying to buy one is assume that – like PCs – the newer models are faster and should be picked over the older ones. That is not how it works.

The short version is: All newer models default to slower speeds so that any game or program meant for 386DX@16MHz will work properly on these. Only software written after the newer models hit the market will know how to enable the faster operating modes, and not all do. There is no need to go for a top 486 Towns unless there is some specific piece of software you want to run that requires it. That being said – given a choice, a faster machine is preferred, it’s default speed is going to be slightly faster than original Towns because it’s not that easy to match it perfectly.

There is however one reason for wanting a newer white desktop Towns beside CPU speed and that is video output. Older machines require a tri-sync monitor that accepts 15kHz, 24kHz and 31kHz frequencies. PC VGA monitors, older and modern, support only 31k. Many games work in that mode but not all. The white Towns (with some exceptions) will up-convert all of these, internally, to 31k. Older ones need an external converter like OSSC to drive a standard VGA monitor.

FAST mode:

Original grey tower Towns used pretty conservative memory settings to cope with slow RAM chips. That’s 3 wait states for main RAM and 6 for Video-RAM.

Starting with CX model (November 1991) Fujitsu implemented what’s called FAST (or High Speed) mode. Any software aware of it can switch to 0WS for RAM and 3WS for VRAM, which is an appreciable speedup. Later machines with 486 CPUs get even more boost since entering FAST mode has a chain effect of enabling the on-chip cache memory. For a 486DX2 that can result in performance 8 times better than the base.

Note that even post-1991 software rarely uses FAST mode, in order to remain compatible with older Towns machines.

The UX model and Marty are equipped with 386SX chip that would normally be slower than 386DX by some 20% or so. To offset that these machines cut the wait cycles down by default – so there is no FAST mode available. Though on the bright side – you don’t get a crippled machine that would be slower than the original Towns.

The UG model has a 386SX CPU @ 20MHz so that’s already more-or-less matching the 16MHz clock of a DX chip, therefore it does have FAST mode. Not a huge difference but it might just make those annoying slowdowns less frequent.

There are ways to shave off some wait states from the earlier Towns even without FAST mode, but:

  • that requires a program to be run first
  • affects only RAM and not VRAM (*)
  • effects will be lost after system reset
  • the earlier Towns generation the slower RAM it has, so less room for improvement

(*) – it seems gen 3 Towns (10F/20F/40H/80H) can reduce the VRAM WS as well accoring to my own experiments, so that makes it almost perfect FAST mode

To use those programs an ODE is required and/or the game images must be modified. Actual FAST mode can be enabled in the same way for software that doesn’t support it natively.

Note: Enabling any performance improving options might break some older programs.

486 cache:

By default all 486 systems will have their cache disabled when booting software. Enabling cache breaks a lot of older software, which was written with hard-coded delays for 386DX. It’s not just a case of games running too fast but also missing or garbled sound, broken FM music and mouse support, as well as random screen corruption and hangs.

With ODE it is possible to enter FAST mode and then disable the cache on a 486 system – that limits the performance boost but also has much higher compatibility. In general there really isn’t any huge advantage to owning a DX2 (or faster) system unless it’s for a specific piece of software that requires it.

Video output:

Unlike PC VGA cards, which used higher vertical refresh rates or various pixel-doubling tricks internally to always ouput >31kHz signal even in low resolution modes like 320×200, Towns machines require:

  • 15kHz-capable monitor for all low-resolution graphic modes (256x and 320x)
  • 24kHz for the DOS/text (and boot screen) 640x 16-color modes
  • 31kHz for 640×480 256-color modes

Note, Towns can combine some modes together to output both 640×480 16-color and 320×240 32k-colors via two graphics planes. It can also scale up parts of the screen surface so for example 320×240 in 256 colors would normally use 1/4 of the 640×480 magnified by 2. These modes would use 31k output.

AFAIK most games that use 15k modes usually default to 24/31 for the first screen, where you can set the final resolution. But, as these are often arcade conversions, some people feel the 15k mode is more true to the original and also sometimes simply runs faster. As a rule of thumb though you need the 24k mode working more than 15k.

24k can be used by games, either all the way or just for some parts like intro or animated sequences. One such example is Eye of Beholder 2 intro, the game proper runs in 31k.

If you can’t be bothered to buy and use external scan converter (that might have it’s own quirks) then a white desktop Towns can do 24k->31k conversion automatically, as well as 15k->31k with the exception of MA and MX models. These can actually do it too but it’s a “hidden option” and the BIOS won’t enable it. 3rd party apps must be run first to use it, see FAST mode notes on how that could be done.

Also, all Towns before EA-based models have the video output on 15-pin 2-row D-Sub connector which requires a custom cable to connect to VGA montitor. EA and later HA machines use VGA output.

RAM upgrade:

Every Towns, except Marty, can have it’s memory expanded with a 72-pin SIMM stick or two (or three). The earlier models will only support 1MB or 2MB sticks but a cheap 4MB PC stick can be installed as well (will not be fully used).

Note: Towns use the detection pins on RAM sticks to tell how much memory is installed. That usually means a typical PC SIMM will require some solder jumpers (migh also use 0ohm resistors or just short pieces of wire) configured properly to be detected and used.

Note: Most games need 2 MBs of RAM and won’t have any better performance with more installed. There’s a few that require 4 MBs (and usually a faster CPU). On the other hand, having too much installed can result in really long boot times for some older software. For tower Towns machines 6-10 MBs is plenty and for 486 systems there isn’t any point in going above 32 MBs. Typically the built-in RAM is enough in most cases.

HDD upgrade:

Possible on all models except Marty and the very first gen 1 towers which lack SCSI controller and need an extra expansion card for that. Note, the internal HDD connector is weird and requires the original metal bay to be present to split it into standard Molex power and SCSI-1 plug.

Original HDDs are typically dead or just about to die, loud as fighter planes taking off. Not very fast either and typically small (below 540MB) due to DOS partition size limits – Towns custom kernel can support up to 512MB per FAT16 partition.

The suggested upgrade would be something like v5 SCSI2SD card, possibly the v5.1 with DB25 connector soldered and used as external HDD drive. That setup doesn’t need the metal bay or installing anything inside the Towns, and usually doesn’t even need external 5V power supply to work.

Note, HDD on Tows is huge topic on it’s own so unless you are prepared to replace that dead battery and do a lot of manual setup work, just forget about it.

CPU upgrade:

Only the first 2 tower generations have the CPU socketed. The rest have it soldered – but a skilled professional will be able to remove it and install a socket.

Marty and the U-models (all-in-ones) all have their CPUs soldered to the mainboard with no socket options at all. The 386SX CPUs can be swapped to 486SLC ones for a minor (10-15%) speed boost unless cache can be enabled. This also requires some skilled soldering.

Desktop Towns have the CPU soldered but will accept special Fujitsu upgrade modules to 486DX(2)(except HG, this one is using 386DX). Models that come with 486DX2 from factory can have the mobo CPU missing and require the uprade board to run at all.

Note: All original upgrade boards have their CPUs soldered, but 3rd party ones exist and have sockets, and even voltage regulators for 3V3 variants of 486DX4. Rare as hen’s teeth though.

Model list:

Here’s a compiled model groups list, with notable differences between them. In general there’s little (if anything) that can be swapped between these groups when it comes to parts and repair.

  • MODEL 1, MODEL 2 (original grey towers) – 1989-02

386DX @ 16MHz. 1 or 2 MBs on-board RAM (can be upgraded to 6 MBs). No HDD, not even HDD controller on-board (requires a separate SCSI card). RAM wait states can be only reduced by one. CPU is socketed though so a swap to 486DLC is trivial.

  • 1F, 2F, 1H, 2H – 1989-11

386DX @ 16MHz. 1 or 2 MBs on-board RAM, wait states can be reduced by two. CPU is socketed.

  • 10F, 20F, 40H, 80H – 1990-10

386DX @ 16MHz. Always 2 MBs of RAM, wait states can be reduced by three. CPU is soldered. Can take 4MB and 8MB memory modules, need a jumper closed below each SIMM slot that’s >2MB.

  • CX series – 1991-11

386DX @ 16MHz. First of the so-called TOWNS II family and last of the towers, has FAST mode.

  • UX series – 1991-11

386SX @ 16MHz, so while a TOWNS II it doesn’t have FAST mode. See explanations above. The built-in CRT monitor is only 10″ but there should be both external RGB output as well as input (so the monitor can be used with other machines). PITA to disassemble and prone to leaking PSU capacitors, not for short-tempered people with no soldering skills.

  • HG series – 1992-11

386DX @ 20MHz. First grey desktop Towns and last of the 386DX machines.

  • HR series – 1992-11

486SX @ 20MHz. First 486 machine and has 4 MBs of RAM on-board. In FAST mode with cache enabled should be twice as fast as 386DX@16MHz but if you really need a 486 machine then you should look for a 33MHz model. Probably a better buy than HG due to more RAM and easier CPU upgrade path.

  • UG series – 1992-11

386SX @ 20MHz, has FAST mode. Last of the 386SX machines (except Marty), other than that see UX notes.

  • Marty – 1993-02

386SX @ 16MHz, no CPU upgrade or RAM expansion options. See UX notes.

  • UR series – 1993-02

486SX @ 20MHz but no CPU upgrade options. See UG/UX notes.

  • ME series – 1993-11

486SX @ 25MHz. First white desktop model, see video output explanations above.

  • MA series (for MA*W see below) – 1993-11

486SX @ 33MHz. 4 MBs on-board RAM. 15kHz video output not converted.

  • MX series (for MX*W see below) – 1993-11

486DX2 @ 66MHz. Belongs to MA family so parts should be swappable. 4MB on-board RAM. 15kHz video output not converted.

  • MA*W series – 1993-11

486SX @ 33MHz. 8 MBs on-board RAM. Belongs to MA family, 15kHz video output not converted.

  • MX*W series – 1993-11

486DX2 @ 66MHz. 8 MBs on-board RAM. Belongs to MA family, 15kHz video output not converted.

  • MF series (including MF*W), Fresh (original) and Fresh-TV – 1994-02

486SX @ 33MHz. 8 MBs on-board RAM.

  • EA series – 1994-10

486SX @ 33MHz. 4 MBs on-board RAM. There’s only one model called EA2? All EA and later models fully convert all video output to 31kHz and come with standard VGA connector.

  • Fresh-T – 1994-10

486SX @ 33MHz. 8 MBs on-board RAM. Belongs to EA family.

  • Fresh-E – 1994-10

486DX2 @ 66MHz. 8 MBs on-board RAM. Belongs to EA family.

  • HA series – 1994-12

486DX2 @ 66MHz. 4 MBs on-board RAM for HA2, 8 MBs for HA53. Newer than EA family so should have VGA output.

  • HB series – 1994-12

Pentium 60MHz. 8 MBs on-board RAM. Belongs to HA family part-wise.

  • Fresh-ES and Fresh-ET – 1995-02

486DX2 @ 66MHz. 8 MBs on-board RAM. Belongs to EA family. T-variant has analog TV card.

  • Fresh-FS and Fresh-FT – 1995-??

486DX4 @ 100MHz. 8 MBs on-board RAM. Belongs to EA family. Uncommon and expensive. T-variant has analog TV card.

  • HC series – 1995-??

Pentium 90MHz. 8 MBs on-board RAM. Belongs to HA family part-wise.