In March 2019, I purchased a beaten-up PC9821 Nw150, which marked my first step into the PC-9800 realm. Compared with IBM PC and its compatibles, PC-9800, especially the earlier models, has many hardware, file system, and handling differences; documents and software are not as well preserved as most western architectures. In the whole process, I stepped on many traps for young players and learned a lot through trial-and-error. I recorded the whole process in chronological sequence, which serves as a good reference for the newcomers.
(Time is written in YYYY.MM.DD format)
I purchased a PC-9821 Nw150 - a Pentium laptop with 86 compatible expanded FM sound source, which makes it a perfect choice for playing Touhou.
The device is beaten-up: two of the threaded metal inserts have broken loose, compromising its structural stability; what's worse, the belt of the floppy disk drive has disintegrated. I attempted to repair the FDD but bumped into difficulties removing the drive (Later told that the correct way to do it is to completely disassemble the machine and first remove the motherboard. What a nasty design).
I purchased a pack of different belts online, replaced the broken one with a similar sized one. However, it still refused to read nor to format any disk, indicating a head alignment failure or maybe just a dirty head. Thanks to the presence of a PCMCIA slot, for the moment I don't have to disassemble again and try to fix it.
Joined PC-9800 Series Central on Discord.
Brought my Nw150 to a Touhou-only event in my school. It was welcomed.
Picked up a PC-9801UF in a dumpster dive. The motherboard is corroded by leaking electrolytic caps. I cleaned it up and recapped using MLCCs (Multilayer Ceramic Caps), but it still won't boot. I didn't dare to try to power it on before recapping, so I still don't know whether it's damaged by the leaky caps beyond repair before my recapping, or is damaged during my recapping process.
ROM Dump: Github
为Nw150更换了同型号的NEC FD1238T软驱，但仍然不能工作。咨询了FH大佬，得到的结论是NEC在PC-98中用的这款软驱是定制的型号，有一些信号有区别，因此不兼容。同理另一个可互换的软驱TEAC FD-05 HG也有类似的问题。需要飞线一个74HC14上去修改连线才可以使用。（全部的资料在这里）
I replaced the NEC FD-1238T FDD in my PC-9821 Nw150 with a brand new one I found on the internet, with no luck fixing the issue.
FlyingHaruka noticed me that the PC-9821 notebooks use a special variant of that series of FDD. The same applies to other compatible FDD models including TEAC FD-05 HG (Which is known to have better longevity).
If I really don't want to buy another PC-9821 that serves as a donor and remove its FDD, I have to either have a hard time fixing it or to do a hardware modification to the new FDD by adding a 74HC14 into the circuit. (Detailed here)
根据上文内容进行修改后这个TEAC FD-05 HG软驱可以正常使用了！我使用了74ACH14施密特反相器的单门版本74AHC1G14，因为这个比较可爱。
I did the modification on a TEAC FD-05 HG, and it works great now. The chip I'm using is 74AHC1G14, the single gate version of 74AHC14 Schmitt inverter.
Obtained a dead 26K soundboard. In the description the seller writes "causes computers to not start-up". At that time I suspected a tantalum capacitor failure, which is known to cause shorted power rails and in turn triggers the self-protection mechanism of the computer's PSU. When I finally got my hands on the unit, I measured a very low to-ground resistance on power rail +12V and -12V. By tracing it on the copper, I was able to spot two problematic caps and have them removed. Now the board is working just fine.
确认了我的PC-9801UV不能进入DOS只能进入ROM BASIC的原因并不是软驱故障（之前还花了很多时间清灰…这个软驱其实挺可靠的，只是非常难拆，比薄型的还难拆，生怕搞坏了，不是很喜欢这个设计），而是单纯因为我之前使用的MSDOS启动盘是在Windows95下制作的，版本太新了。网友帮我做了一张MSDOS 3.3的，使用起来就没有任何问题了√
I have a PC-9801UV - a decent looking V30 machine with dual FDD built-in. I was not able to boot DOS on this machine and can only fiddle around in ROM BASIC. Initially, I thought there might be something wrong with the FDD and attempted to clean it (which is difficult as hell, it's much harder to take apart safely than a compact one). With the help of my friend on the internet, now I know that the boot disk I made in Windows95 has a DOS version that's too new for the architecture; an MSDOS 3.3 disk works just fine.