Nan Tan 3500 Series

The Nan Tan 3500 Series (also known as the FMA3500/FMA3500SX/FMA3500C) were 486-based laptops, first released around December 1991. There are two main revisions of the series - the 3500/3500SX, and the 3500C. The 3500/3500SX have grayscale LCDs and look identical to the 386-based 3300. The 3500C uses a color display and has a different hinge design, but otherwise looks very similar to the earlier revisions. Some of the FMA3500C models have a trackball above the keyboard, others don't.

Most 3500 Series laptops have a white/beige case, but some did come in a dark gray.

One odd design quirk of these is that the battery screws on to the back of the laptop with thumbscrews, rather than slotting into any internal bay. That's definitely a dated design for the time these were released. In fact, the overall design of these (especially the earlier revisions) look a couple years older than they actually are.

The 3500 dock screwed onto the back in place of the battery and added two ISA expansion slots.

The 3500 Series laptops were sold by a huge number of distributors. Here's a list of names they were sold under:

3500/3500SX

Aspen
Ergo NoteBrick/NoteBrick II
Santron 486DX-33MHz
Sager NP-206, NP-207, NP-209, NP-210
AMS Tech Notebook 486-33C
Royal Computer 486DX/33
MDS NoteBook 486DX
Micro-International HCP Power Notebook

3500C

Broadax Systems (BSI)
Sager NP-206C

Most of the info here came from creepingnet.

Specifications

Spec	3500 Series	3500C
Release Date	~December 1991	~December 1992
CPU	CPU Type: Socket 2 - Intel 486SX @25 or 33MHz - Intel 486DX @25 or 33MHz - Intel 486DX2 @50 or 66MHz
Chipset	Unknown
RAM	Type: 4x 30-pin SIPP memory slots Standard: Unknown Maximum: 32MB
Storage	3.5" IDE Requires Adapter: Uses proprietary power connector, requires adapter to use a standard drive Standard: Conner Peripherals
Display Options	9.4" Passive Matrix Grayscale @640x480 (Casio MD820TT00C1)	- 9.4" Passive Matrix Color @640x480 (Sanyo LCM-5331-22NTK) - 9.4" Active Matrix Color @640x480
Graphics Chipset	Cirrus Logic GD6420 or GD5424 VRAM: 1MB
Audio	PC Speaker
Main Battery	External 8-cell NiCad
CMOS Battery	NiCad Varta barrel battery (soldered)
Power Supply	3 or maybe 4-pin DIN connector (i have seen references to both), 20V	Barrel Jack (20V)
Media Drives	3.5" 1.44MB Floppy Drive
PC Cards	None
Networking	None
Other I/O	- 1x Parallel - 2x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x External FDD Connector - 1x Numpad conector
BIOS	Award or Phoenix
Pointing Device	None	Optional Trackball

Resources

NOTE35C.zip - Notebook FMA3500/3500C/3500SX Utilities - gets function keys working, other stuff.

3XVGAW95.exe - FMA3500 Video Driver

Common Faults & Maintenance

CMOS Battery leaks

The 3500 uses a VARTA NiCad barrel battery to back up the CMOS. These batteries nearly always leak in their age and MUST be removed to prevent the laptop from getting nuked.