FM Towns:CPU Upgrade for Desktop Models
Basic information
Desktops had a slot to place CPU upgrade cards with some later models requiring the CPU upgrade card to be present as there wasn't a CPU onboard the motherboard.
There was absolutely zero retail software that required anything more powerful than a 486DX2 CPU and the majority of software was designed for the base 386 model in mind.
The white desktops with 4 expansion slots are optimal as some CPU upgrade cards were taller and designed for them.
The white desktops with 3 expansion slots are shorter and thus more limited on CPU upgrade cards.
The 486DX4 cards for the Towns MX/MA type desktops will work in a smaller desktop (EA/ME). However, you won't be able to close the top lid.
Spotting cards in auctions
Sometimes sellers on Yahoo Auctions Japan will have the lid taken off of the computer.
This is a good opportunity to see if a CPU card is present or not.
It will also generally raise the price.
List of CPU Upgrade cards divided by Desktop type
- FMT-361
Official Fujitsu Product. For HR desktops only. 486DX2 @ 40MHZ - PK-FM486
By I-O Data Equipment. For HR desktops only. 486DX2 @ 40MHZ - (Unknown Model number)
By SoftBank Corp. For HR desktops only. 486DX2 @ 40MHZ
- FMT-3621/3621A
Official Fujitsu Product. For ME desktops only. 486DX2 @ 50MHz
- FMT-3623
Official Fujitsu Product. For MA/MX only. 486DX4 @ 100MHz - FMT-3622/3622A
Official Fujitsu Product. For EA/MA/MF/Fresh only. 486DX2 @ 66MHz - ODBT486F
By Urban Corporation. 486DX2 compatible CPU (5V) support. Should fit most desktops except HG/HR - ODBT486Z
By Urban Corporation. The Holy grail and best card as it supports 486DX4 CPU (3.5V) and can use a 5x86 CPU.
Often sells for $100-300+ on auction. Fits all desktops except HG/HR. - ODBT486
By Urban Corporation. 486SX/DX/DX2 compatible CPU (5V) support - FMT-3651
Official Fujitsu Product. For HA Pentium only. 60mhz. - FMT-3652
Official Fujitsu Product. For HB/HC Pentium only. 90mhz.
In addition, the Pentium models can accept the following CPU upgrades.
- PentiumODP(120/133MHz)
For HB Model only. Overdrive processor. - PentiumODP(150MHz)
For HC Model. Overdrive processor. - PentiumODP(166MHz)
For HC Model. Overdrive processor. - MMXPentiumODP(166MHz)
For HC Model. - MMXPentiumODP(180MHz)
For HC Model.
There are also reports of users putting a K6 CPU inside a Pentium HC model.