Editing Tai-Hao TH-5539 (section)

==TH-5539-1==
Confirmed only as "APC-1". This is a flat, minimalist design with no margin above the function keys for a legend strip. The shape is very similar to TH-5539-3, without any adornments, and with the status LED panel lined up with the function keys as there is no recess for a badge. This can be seen in the Tai-Hao brochure. In the 1992 example below, the switches are APC-branded, and the PCB is marked "APC-3A", indicating that APC-3 and APC-1 share the same PCB.

<gallery widths="250" heights="187">
File:Tai-Hao APC-1 -- top.jpg                              | Top
File:Tai-Hao APC-1 -- side.jpg                             | Side
File:Tai-Hao APC-1 -- bottom.jpg                           | Bottom
File:Tai-Hao APC-1 -- keycap detail.jpg                    | Keycap detail
File:Tai-Hao APC-1 -- keycaps, underside.jpg               | Keycaps, underside detail
File:Tai-Hao APC-1 -- enter keycap.jpg                     | Enter keycap
File:Tai-Hao APC-1 -- internals with some keycaps.jpg      | Internals with some keycaps fitted
File:Tai-Hao APC-1 -- internals.jpg                        | Internals
File:Tai-Hao APC-1 -- PCB, bottom.jpg                      | PCB, bottom
File:Tai-Hao APC-1 -- various details.jpg                  | Various details; the controller IC is dated 9240 (week 40, 1992)
File:Alps.tw Type OA3 -- APC branded, steel click leaf.jpg | Switch disassembly
</gallery>