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Amstrad Hardware Recyling

information and tools about doing unexpected things to Amstrad hardware

Published: 2016 November 3

Amstrad seem to have a talent for producing interesting hardware. Leaving aside the Amstrad PCW --- possibly the most popular CP/M machine in the world (largely because noone knew it ran CP/M) --- they have also produced some other, more exotic devices, some of which I own.

The NC200 is one of the most unusual laptop computers ever made. The NC-series of notebooks --- there were three different models --- ran off consumer batteries, had a full moving keyboard, solid state memory storage and had a battery lifetime of ten to thirty hours. They were based around a Z80 and ran their own custom OS. They have an excellent keyboard, a small but clear screen (80x16 character with bitmapped graphics; I don't have the exact resolution offhand), it's got a decent simple word processor, lots of storage, and can read and write DOS-formatted 3.5" floppies. Boot-up time is nil; press the button and it goes.

The NC200 went out of production in around 1990. See here for more information about the NC notebooks.

The Amstrad e-mailer is a smart phone appliance thing and consist of a chuny desk phone with a respectably sized screen, pull-out qwerty keyboard and lots of buttons. The most recent version, the E3 videophone, has a colour screen with a video camera attached.

There are currently three different models. The E1 is no longer available. The E2, one of which I own, has got an ARM7TDMI processor with 8MB RAM and 8MB flash and runs a proprietry embedded OS. The E3 has an ARM9TDMI with DSP and more memory, and runs Linux (although not in a useful way). Both devices have a mysterious EXP port on the back that turns out to be a serial port in disguise, although to access it on the E2 you need an RS232<->TTL line level converter, which can be used to replace Amstrad's firmware with your own custom software. See here for more information on the e-mailer hardware.

In order to talk to the E2, you need the appropriate cable. Irritatingly, while the E2 has a serial port, it runs at TTL line levels not RS232 levels. This means that if you're going to connect it to a PC, you need a line level converter.

One approach is to build a MAX232-based interface board, which I've done, but this is inconvenient as it requires powering. The other alternative is to find an appropriate mobile phone cable and hack it; a lot of mobile phones use a similar communications scheme. This is what I'm doing. It's a lot easier --- and considerably neater --- than building your own level converter on breadboard.

Here are pictures of the cable I'm hacking. It's a Nokia 5100 cable bought from eBuyer for about three pounds. In order to make it work on the E2, the mobile plug gets snipped off, and a 2.5mm jack gets attached. You need to connect:

  • GREEN (ground) -> sleeve
  • BLUE (tx) -> ring
  • WHITE (rx) -> tip

Then just plug it in and it works.

The front of the PCB:

[Image of the front of the cable's interface PCB.]

The back of the PCB:

[Image of the back of the cable's interface PCB.]

The entire cable:

[Image of the entire cable.]