Most information for the FMT are going to be in Japanese. Just translate to your native language. If you can find other resources let me know I can make an edit and place it here!
Deunan did an excellent summary write-up of FM Towns models and capabilities. This is perhaps the best English article I’ve ever found. Very good Deunan!
The next best source I’ve found is here. Goes into detail with every single model, every single accessory and peripheral, the pinout for the hard drive connector and also adding RAM. This is when you have to translate the page but this website is generally the best piece of information regarding the FM Towns computer.
Here is some good tips on using a Towns original monitor! Specifically which one can do 15khz, 24khz, 31khz. Also if you own a Towns MX/MA it tells you how to edit TBIOS file on your hard drive to enable 15 to 31khz conversion. Natively the MX/MA models perform internal 24 to 31khz conversion. This can be helpful for people limited on their display or monitor options
Here is a good page on gamesSX explaining how to write floppies for the japanese computer. Personally I use a different approach that I will cover in a later post.
Here is my google drive link. This link has the only known Towns Doujin I’ve ever seen. It was kindly scanned and sent to me by Mr. Hota from the TowTow doujin circle. It was out of print and I asked Mr. Hota if I could buy it. After discussion he decided to scan and send me on email. Thanks Mr. Hota!
For software programmers you can take a look at the “Redbook” on archive.org It will also have pinouts for the different FM Towns connectors on the computer. This was especially helpful for me when I was investigating SCSI connector and expansion card slots. There is also memory map explaining in great detail address locations. However it is in Japanese but by a mile the best resource for programming at RING 0. Expect ASM and C..mostly ASM.
Also the last website is a work in progress just like this one but Mr. Windy also made a Towns wiki! I will be actively posting there in addition to this page.