Some infos on the connectors:

CN3 / CN3 connect the backplate to the sysboard.
The backplate holds
- serial port
- parallel port
- video port
- "pointing device connector"
- on/off switch
- speed auto / max
- resume on / off
- video normal / inverse
- volume slide
- all LEDs
 

CN14 (located over the memory connector towards the board edge) + CN15 are the IDE HD connectors for a strange split cable   Your CN14, seems to be CN13 in fact and is the standby backup battery connector (used during battery changes)
 

Almost correct, but Peter is complaining about his own scan when he say I got some of it wrong...

   The (?) ROM is a PLCC OTP-version of the 27C1001 (1284K x 8). Not eraseable - One Time Programmable (a PROM so to say). .

>Please note the dotted outline on the bottom side of the planar for
IC56, a surface mount 387SX-16. I wonder... Peter, would the possibility exist for S.H.I.T. to happen with the installation of a surface mount 387SX?

Err ... very theoretically yes. How are your skills in SMD soldering ?

   The 387 sits very close to the 386SX and you only need to "pull wires" to an empty spot on the sysboard. Obviously they designed the system *with* the 387 - but that thing was darned expensive back in '92 or so  - so they left it away. You won't run AutoCAD on a 386SX-class notebook anyway.
   The PLCC socket has the same pinout. So you could use a socket and a PLCC chip too. But *that* may fail due to the lack of room to the modem port. But what - cut that crap away. No one uses the proprietary 2.400 bd modem in a N33.
   BTW: The N33 case has *lots* of room otherwise. Seems as if it was planned to either put a much bigger HD in that case *or* (more likely) have the FDD internally. The one internal framepart has holes that perfectly match the FDD used in the TP700/720/ PS2e. By what reason they
decided to buffer the FDD signals on a separate board and attach it externally via a strange Mini-Centronics 30-pin (I think, must count).

   The 8533 N33 was originally a machine developed by IBM Japan for
domestic markets. After the arch-rival Compaq brought the E-Lite 386
laptop series IBM was forced to bring out a counter-product.  IBM Japan
at that time had about a dozen different laptops and notebooks out. 
   The N23 didn't make it to here, the N51 (8551) has been adopted as well
as the CL57SX Color Laptop (8554 - hence CL54 in Japan) ...  The CL57
identifies itself as PS/55 in the BIOS - PS/55 machines *are* domestic
japanese machines intended for local markets. The L40SX (8543) was a
japanese/US co-product, where the technology came from Japan - and the
design, marketing and supervision was located in Boca Raton. That was
unneccessary complicated and lead to a near 1-year-delay of the project
L40. 
   The N33-X13 was a "quick shot" derived from the N23 - they changed the
keyboard to US/Euro style (along with the sysboard by what reason) and
they cut down the 386SX to 12MHz for a low-entry model, which never
really took off. The better -X15 version introduced a little later had
16MHz SX and external video port.
   The N45SL (2614)  -by the way- is a Zenith OEM based on ISA/AT
technology, which IBM bought to extend the line of machines. The PS/note
182 (2141) was also an OEM machine from Japan as far as I know. Has been taken to introduce a laptop in the PS/1 family.

G13 unit it has no external video port and 386SX-12, a -G15 has external video port and 386SX-16. Max. memory 6MB, B/W LCD 10.4", 640 x 480 / 16 greyscales. HD either 40 or 80MB. 

I have a -G15. They have some "classical defects": either don't work at all, or work only on battery or AC power but not on both. Batteries die very soon, short runtime on batteries anyway. HD can be replaced against standard 2.5" Laptop IDE drive of either size up to 8GB - given you have a good disk-manager software.  (Mine has an 850MB currently installed).

The N33 takes 6MB total. 2 onboard - one 4MB module with "minor rework" if it isn't the exact part for the N33. I use 4MB/70ns Parity and rework the connector and the presence detection. Easy doing. 5 minutes or so.
- the memory module is a particular module ... says IBM. But if you use a sharp cutter or plier you can cut out the "nose" in the memory module connector to make standard 72-pin Simms fit in there. This is one half of the action - the other one is the proper presence detection. The dirty details on that are on my page http://members.aol.com/mcapage0/memory01.htm
In brief: if you modify a 4MB / 80ns or 70ns 36-bit Parity module you need to remove the coding "bridges" for the pins 67 and 68 and solder the bridges for pins 69 and 70 ... that's all. On Martins machine I used a spare 4MB / 80ns Parity which has bridges for all four pins 67 - 70 and removed the two for 67 and 68. Works fine - the N33 requires only 80ns memory, but the 70ns modules are often easier to get.

   About the drive current: AFAIK the 80MB WDA-280 is rated +5V / 0.7A, the 60MB Conner CP2067 IBM used occasionally is rated +5V / 680mA.
I used a Toshiba HDD2517 814MB drive rated +5V / 0.7A and its smaller brother with 340MB for quite some time in my N33 with no problems. I would guess that even 1A doesn't do much on the DC/DC circuit .... but on the over all runtime on batteries (if they work at all).
   Helmut has a 2.1GB Toshiba in his N33, and Martin ("Spooky") also uses a bigger drive (540 ? forgot what I installed years ago when he came over the first time). Also with no problems. So I think the most modern HDs will do fine in there. 
   Problem is to find an appropriate Disk Manager - most newer versions are "manufacturer-dependent" and you cannot install a Toshiba with a WD or Maxtor version.
   I really love my N33. I use it as intelligent terminal (for routers, switches
and hubs) and outdoor wordprocessing. Maybe I build a large solar panel for it recently. :-)

Peterwendt wrote:

> Problem is to find an appropriate Disk Manager - most newer versions
> are "manufacturer-dependent" and you cannot install a Toshiba with a
> WD or Maxtor version.

http://www.ontrack.com/diskmanager/[...]
Product Features Supports installation of any manufacturers hard disk drive, including Fujitsu, IBM, Maxtor, Quantum, Samsung, Seagate, Toshiba, and WD. Break the following capacity barriers: 528MB, 2.1GB, 4.2GB, 8.4GB,
and NOW 32GB!

I replaced the blown fuse, replaced the tiny 80MB HD with -currently- a
340MB type I had around (it *did* run with a 1.2GB as well - but I needed that drive for a different project) and I crapped out one of the dead batteries and replaced the cells. They are "3/4" types and all six cells cost about 30 Euro. Now the machine nicely runs for about an hour on battery.

* DEFAULT.BAT, DEFAULT.CMD: These programs set all the operational features to the default values. The default assumes external power (AC or Car Battery) supply operation.

* TRAVEL.BAT, TRAVEL.CMD: These programs set all the operational features related to the power supply by the Rechargeable Battery to the values that make the battery life as lengthy as possible.

* PRINTCOM.BAT, PRINTCOM.CMD: These programs turn off and on the parallel, serial, and communication interface connectors at the same time.

* EXT_PWR.EXE: This program detects what power source the computer is using, and returns two kinds of codes depending on the power sources. You can use the return codes as the conditions as to manage the power usage.

* SETUPPWR.BAT, SETUPPWR.CMD: This is a sample program which uses EXT_PWR.EXE. It runs the TRAVEL batch program if the power is supplied by the Rechargeable Battery or if the power is supplied by AC or Car Battery adapter, it runs DEFAULT batch program.

* DISCHRGE.BAT: This program is used to discharge the Rechargeable Battery.