The Tandon NB/386sx page


Being unable to find much about this notebook on the web (just tons of sites offering batteries for it and, which went down in November or December 2000), I decided to create a page about it myself.
This notebook was made by the Taiwanese company "Full Power Investment Co. Ltd." a.k.a. Compal (model BC380/BC380A/BC380B/BC390) and was produced from 1991-1993. It was sold by Tandon, Compudyne and PC Brand (perhaps by others as well). Here in Germany, the Tandon model was sold, and as it seems, it was quite popular in its day.

Technical data

CPU Intel i80386SX 16, 20, 25 MHz (BC380, BC380A, BC380B; NB/386sx); later: Cyrix 486SLC 25 MHz (BC390?; NB/486slc)
Numeric co-processor Socket for i80387SX and compatibles
RAM 2 banks for ordinary 30-pin SIMM modules with 80ns or less (2 per bank, so there's room for 4 modules); 2 1-meg (low-power) modules standard; modules with up to 4 MB each are supported, resulting in a maximum amount of 16 MB of RAM
Bus system ISA (16-bit, I assume), 7.25 MHz
BIOS unknown mfr; versions I've seen: 3.73, 3.76; supposedly there's also 3.8
Graphics chip Cirrus Logic CL-GD610/620, VGA compatible; the BIOS seems to be from an ordinary desktop graphics card
Display 8.4" FSTN (Film SuperTwisted Nematic, a cheaper version of DSTN = Double SuperTwisted Nematic) 640x480 greyscale display (32 shades of grey)
Hard disk 30, 40, 60, 80 MB 2.5" IDE hard disks (type 08, 17, 24, ?); BIOS supports up to 200 MB (BIOS 3.7x), up to 504 MB possible with BIOS 3.8, with a disk manager larger disks are no problem (my NB/386sx with BIOS 3.76 has a 1033 MB Toshiba)
Floppy 3.5" HD, BIOS supports step rates of 10 and 13 ("3mS")
Connectors/ports PS/2 keyboard, proprietary ISA bus connector, two 9-pin serial ports (UART: 16450), one parallel port, one 15-pin D-Sub VGA connector, no PCMCIA
Optional components Internal 2400bps (data) / 9600 bps (fax) modem, can be used alternatively to the 2nd COM port
Power saving features Display/harddisk can be set to switch off after a certain period of time, CPU put in standby when no input/output occurs, dedicated button for standby mode (CPU, hard disk, display off)
Battery 4.8 V, 5000 mAh, looks a bit like a sausage (but is yellow); seems to use 4 NiCad cells of D-cell size

Interesting details

In text mode, you can change from greyscale to black/white, use bold instead of normal characters, switch between internal and external display (no option for displaying things on both yet), reverse the display (meaning you get black text on white instead of white text on black) and enlarge the characters to get a full-screen text mode. This only works if BIOS functions can be used though - in protected mode in Linux or OS/2, nothing happens, and a DOS box in Windows has to run in full-screen mode for these functions to work.
Another interesting detail: The display hinges aren't where you can find them on most notebooks today (at the back edge), but more where you'd expect them on a laptop computer (about 3 cm from the back). Perhaps that has been done to make the display appear larger. The covers for the ports are definitely a weak point of this notebook - they break quite easily. IMO this problem shows that the manufacturer (Compal) didn't have much experience in building notebooks at that time. But I think that's nothing unusual: Back in 1991 the market was still dominated by laptops and (PC) notebooks were pretty new, so the experience simply wasn't there yet. This could also be the explanation for the unusual position of the display hinges - on laptops these aren't at the back edge either.


Ctrl-Alt-Ins Lets you boot from another device
Ctrl-Alt-Esc Enters the BIOS setup (don't forget to set the correct date after exiting it, it's not quite Y2K proof)
or on an external keyboard:
Ctrl-Alt-"-" ("minus" on the numeric keypad)
Reduces the CPU clock to 10 MHz (20 MHz model)
(German keyboard, it's the key directly below P)
or on an external keyboard:
Ctrl-Alt-"+" ("plus" on the numeric keypad)
Restores the full CPU clock
The following hotkeys work in text mode only:
Fn-F6 Switch from greyscale to b/w mode and vice versa
Fn-F7 Switch from normal to bold characters and vice versa
Fn-F8 Switch display: internal (LCD) / external (D-Sub)
Fn-F9 Reverse display
Fn-F10 Switch character size: normal/enlarged

The status LEDs

The notebook has three status LEDs, one for the battery, one for the hard disk and one for the floppy drive. The following table shows what the various colors mean:

The battery LED:
orange The notebook is powered by the power supply.
green The notebook is powered by the rechargeable battery.
red and green, alternating The rechargeable battery slowly gets empty.
red, blinking The battery is almost empty. Save your work ASAP.
yellow (undocumented?) The CMOS battery pack (it consists of four AAA NiCads or perhaps 1.2 V batteries) is almost empty.
The hard disk LED:
green Hard disk access - trivial, I know.
The floppy LED:
green The floppy drive is being used.


1. The display

It's very small, not very bright (virtually unusable in direct sunlight) and doesn't have all that much contrast. In addition, the contrast changes depending on the display's temperature.

2. The keyboard layout

I know - notebook keyboards are always a compromise, but the position of the Ctrl and Caps Lock keys annoys me: Caps Lock is where you'd expect Ctrl and vice versa. In addition, I'm not very happy with AltGr being Fn-Alt.

3. The battery

Since the notebook isn't the newest one any more, the batteries are in less than desirable shape - one of the two batteries I have is completely dead (U=0), the other one still has enough voltage, but its capacity is about zero and it won't charge. That wouldn't be much of a problem if the notebook didn't require a working battery to power up! It won't power up at all with the dead battery. Fortunately the battery seems to consist of not much more than 4 NiCad cells of D cell size, and these are fairly cheap in comparison to a whole new battery. (BTW you should not use normal non-rechangeable batteries, since the notebook could be damaged because of the higher voltage.) Perhaps one could even replace the dead cells in a dead battery with NiMH ones, resulting in a "super battery"?

4. The door of the battery compartment

The battery is pretty heavy, and the door of the battery compartment seems to be a bit weak for it - on one of my NB/386sx notebooks (I have two of them; the second one is obviously defective) it doesn't stay closed any longer, on the other (defective) one it has a crack.

5. The display hinges

The display hinges seem to be a weak point as well. Achim Lohse writes:

One warning - the hinges on this model are the Achilles heel (at least on my PC Brand version). That's how I got to buy mine. It was sitting at a consignment shop which I visit only occasionally, as I live 3 hours' drive away. The hinge springs had broken through the plastic lid locked it up so that one could neither open or properly close the notebook. So no-one was able to run or examine it. I had to spend more than an hour on it to remove the damaged hinges just so I could test it.

6. Strange power plug

The pinout of the power supply jack on the notebook is not documented. Thanks to Danilo from Brazil for this pinout:

     __ __ __

      _ -- _
    +        +
  / o1  o2  o3 \   
 |  o4   o5  o6 |   Pin 1,2: +7V  0.5A (charger battery)
  \  o7   o8   /    Pin 4,7: +5V  2.5A (power supply)
    + _    _ +      Pin 6,8: Ground (GND)
        --          Pin 3,5: Not usage

7. Just where's that CMOS battery?

In my spare non-working NB/386sx, it's made up of 4 AA cells (NiCd I think) squeezed in next to the floppy drive. To get there, flip over the NB/386sx, remove the three rubber feet at the front and remove the screws underneath. Carefully turn it over again and open the lid. The keyboard can now be removed (be careful with that ribbon cable) and leaned against the display. Now, look at the front right. It may be that the 4 cell solution was an aftermarket replacement, but if memory serves my other NB/386sx has it the same way.

About my own NB/386sx

My NB/386sx browsing the Win 3.1x systems page with Netscape 3.01 Gold

I bought my Tandon NB/386sx at the beginning of June 2000, rather for nostalgic reasons (my first computer had a 386SX-20 as well) than for any rational ones. It has a 386SX running at 20 MHz, 4 4-meg SIMMs (so it has 16 MB of RAM, exactly the maximum amount a 386SX can address), a 1033 MB Toshiba MK1003MAV hard disk (with Ontrack Disk Manager 6.03), and it even has a co-processor, an IIT 3C87SX (that's a co-pro in CMOS technology with very low power consumption which, however, is not 100% instruction compatible with the Intel 387SX). It runs DOS 6.2 and Windows for Workgroups 3.11, which I'm even using to connect to the 'net via an external 28.8 modem (I'm running the port at 38400 bps, but at this speed the setting COM2Buffer= in system.ini, [386Enh] must be at least 2048 (!) to avoid character loss). Sometimes I also boot a floppy Linux distribution on it (mostly tomsrtbt), but I'm not too happy with those - tomsrtbt runs fairly quickly, but takes eternally (minutes) to boot (things have to be uncompressed, which is a bit slow on a 386SX, as you may be able to imagine), MuLinux boots faster, but shutdown lasts an eternity. I'm mainly using it as a mobile data storage device for updates (these are copied to and from the notebook via Norton Commander 5's Commander Link function over a serial null-modem cable); the 1 gig HD is useful here :).

The mysterious "expansion box"

What I'd very much like to have is the "expansion box" or "expansion unit" (mentioned on p. 110 of the manual in German). It provides two ISA slots (16-bit, I assume), one of half length and one of full length, and obviously you can also connect a hard drive and a floppy to it, so it seems to be an equivalent of today's docking stations. So far, I've been unable to find one - I couldn't even find someone who has used or seen such a thing before :(.

Update: Seems the thing was never really sold by Tandon. Well, my NB/386sx doesn't see much more use anyway these days, so...

Created: 2001-01-02
Last modified: 2004-03-06

Author: Stephan Großklaß