Amstrad NC-100 and Amstrad NC-200 laptops with Z80 CPU

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Amstrad NC-100 and Amstrad NC-200 laptops with Z80 CPU

Both computers come from around 1992

SRAM cards

Cards to search for: PCMCIA Type 1 SRAM Card , <= 1MB. (It is rumored that 2 MB cards can be used but only first 1MB is usable then, I have not tested that).

These cards contain SRAM chips and a battery for keeping RAM content over some time (about 1 year). The card shown below uses a 3 volts lithium battery type DL2325, but this varies from card to card.

Examples: Apple Newton SRAM Card 1MB (all larger cards are not of SRAM type and will not work). SRAM cards are hard to get nowadays.

See also:

Amstrad NC-100

to be done

Amstrad NC-200

Back side, battery cover removed:

Upper case part lifted. The plastics used for the case is not very tough, so it is required to be super cautious when opening the case, not to break it.

Look on display in upper part of opened case.

Floppy drive removed. Now the PCMCIA slot can be seen:

The big chip named “Amstrad 41898 998-10190 T9942A” from calendar week 22 1993 contains Z80 core and additional logic for interfacing all devices like floppy drive, display, serial connection etc. So it is a chip custom made for Amstrad. This is a different approach than used in the Amstrad NC-100, where they have used several chips, including a stock Z80 CPU, to realize the product.

This big chip is an ASIC, and is called “NC200 ASIC” by service manual.

The small multi-pin chip below the PCMCIA card slot is a M5M51008AVP-10LL, which is a 128KByte 100ns SRAM.

There is also a free location for an Hitachi HN62334BF chip. This is a 4MBit (512K x 8 Bit) ROM chip with 32 pins. I could not find any information what this was intended for. Maybe an additional ROM, with its vast size could contain heaps of additional applications and even operating systems. So, this looks very interesting to have a more in depth look at it, but it seems nobody did this so far.

Backlight voltage generator, slider for adjusting display contrast, and small power button can be seen here:

Floppy drive. This was defective, as usual in these old computers. The belt is broken. I’ve ordered a new one. In the picture, the upper part of the drive was already lifted, this is required to exchange the belt.

System ROM, calendar week 05/1994. It is called “Amstrad 999-14000 0” and has part no. “42112 UK C1”, which is called “NC200 System ROM (UK)” by service manual.

Floppy Drive

The devices were sold with a Citizen V1DC-65B drive. It offers 720KB and the format used is compatible with DOS disks, so files can easily be exchanged with a PC. HD disks can be used, if the HD hole is covered with intransparent adhesive tape.

This drive was rarely used anywhere else and so replacement drives are very hard to get. Usually, belt is broken. Good news is belt can be replaced, replacement belts available from UK ebay sellers.

For my device, a belt was needed. The image below show how the belt is arranged. It is required to lift the disc motor (upper right). After changing the belt, the drive was immediately working.

The disk has an unusual connector, 1x26 pin flexcable, info on the pins e.g. here: https://old.pinouts.ru/HD/26pin_microfloppy_pinout.shtml and here https://www.martinruss.com/sy99adapter.html and some discussion on that micro connector here https://forum.vcfed.org/index.php?threads/non-standard-citizen-26-pin-floppy-drives.56976/

Old file formats together with Linux

CP/M comes with a set of old file formats, where special tools are required to handle them on nowadays Linux:

CP/M like OS

Linux like OS

See also

General Amstrad NC links: