The Amstrad NC100


The NC100 is a Z80-based portable computer released by Amstrad in 1992. It has 64K bytes of battery-backed CMOS memory, which means that its RAM will not lose its content when the device is powered off. The machine has a 80x8 character LCD screen and a full-size keyboard. Its size is about 30x20x2.5cm and it weighs a little more than 1kg. Here is a picture of my NC100 running CP/NC.

The NC100 was originally intended to run applications from its internal ROM, but it can also boot from from a PCMCIA SRAM card, so installing a different operating system is straight-forward. (Well, not that straight-forward, it turns out.)


CPU Z80 @ 4MHz
Memory 64KB CMOS SRAM, 256KB ROM,
   plus up to 1024KB CMOS SRAM via PCMCIA card
Screen  480 x 64 pixel passive-matrix monochrome LCD (80 x 8 text)
Keyboard  64 keys, full size, full hub, rubber-dome
Connectors  RS232 port, parallel port, type-I PCMCIA slot
Power  6V DC (battery or connector)
Batteries  4 x AA alkaline cell (main power)
   1 x CR2032 lithium cell (CMOS RAM)
Battery Life about 20 hours


NC100 Mainboard

The NC100 is quite serviceable. There are no moving parts except for the keyboard, and the main sources of trouble are corrosion on the connectors and the keyboard membrane. There is a total of five screws holding the computer together, plus a few more in the keyboard.

The mainboard looks clean and simple and there is just one weird chip, which appears to be involved in memory mapping, keyboard decoding, and maybe a few other things. Here is a picture of the NC100 mainboard. Descriptions of the parts follow below (many of them taken from from Hans Boehling's Surgical Guide to the Amstrad Notepad Computer).

 1 battery case, 4 x AA
 2 type I PCMCIA slot
 3  Z84C00 CMOS CPU, Z80 compatible
 4 keyboard connector (2x)
 5  NEC D27C2001 (memory management unit? keyboard decoding? other?)
 6 TC8521 real time clock
 8 Display connector
 9 UPD27C001 CMOS EPROM 256K*8 bit, socket on backside
10 UPD43257A CMOS SRAM, 32K*8 bit (2x)
11 UPD4711 RS232 driver
12  Speaker connector (piezoelectric speaker)
13 LCD contrast dial
14  external power connector (6V DC, 300mA)
15 power switch
16 RS232 connector, DB9 male
17  parallel port connector, DB25 female

For more questions (and answers) about NC100 hardware, see the Hardware FAQ on Tim's Amstrad NC User's Site.

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