The N23 name comes from this machine's model type 5523. It was the second generation PS/55 Note (the 55xx series in Japan being similar to the Western PS/2 series). The first generation PS/55 Note didn't have room for both a floppy drive AND a hard drive, so you picked either as an option. The motherboard has the same EXCEL codename as the N33 16Mhz.
Side Note: Originally 5523 type was for the Notebook models and 5535 type was for Laptop models of the 55 Series.
The PS/55 N23 SX is a very close Japanese relative to the Western 16Mhz N33, although the Japanese N23SX is better because it had both the FDD and HDD built in. I theorise that as the 12Mhz PS/55 Note & N33 could not fit a both as HDD and FDD inside due to the two-part mainboards, so it had to have an external floppy The N33 16Mhz had it's floppy drive deleted to align both N33 machines so that both only had an external floppy connector. Although one could argue that having an internal floppy along with faster 16Mhz 386 and external video could have been a greater selling feature for the more powerful N33.
Some might consider this machine 'one' of the grandfathers of the IBM Thinkpad 700C due to it's dark case, bento-box form factor and 'nice' keyboard.
My one had the same blown cylinder fuse, as was inside my N33 16Mhz. After replacing this, it boots fine (with the battery pulled out). However it has no LCD.
Here is a picture of the inside, which, apart from the floppy drive is very similar to the 16Mhz N33:
And with the floppy drive and insulation moved to one side:
Here is a picture of the internal floppy drive - missing from the N33 models:
My machine doesn't boot at the moment because I cannot find the correct reference disk.
