Let’s take a look at Viewdata via the Amstrad CPC
This is a blog post about the first time I’ve ever connected to a Viewdata system.
Wikipedia says the following about Viewdata
Viewdata is a Videotex implementation. It is a type of information retrieval service in which a subscriber can access a remote database via a common carrier channel, request data and receive requested data on a video display over a separate channel. Samuel Fedida was credited as inventor of the system. Fedida had the idea for Viewdata in 1968. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels. This is in contrast with teletext.
I’ve never seen Viewdata before – until last night!
For this experiment, I needed a Viewdata terminal. Unfortunately, I down own a proper Viewdata terminal. So I decided to use my Amstrad CPC6128. Why the CPC I hear you ask! Well, I know that the RS232 interface I have for it can emulate a Viewdata terminal using the onboard ROM Commstar and HoneyTerm.
The next issue was to connect the CPC to the internet. The simplest method I had to hand was to use a Raspberry Pi with a USB to Serial cable. A simple command run from the command shell was all that was needed to bring up a login prompt on the CPC.
getty -L /dev/ttyUSB0 2400 vt100
You can break down the above command into the following parts
- getty : Get Teletype. Used to connect a serial terminal to a Unix host. More info here.
- -L : Force the line to be a local line with no need for carrier detect.
- /dev/ttyUSB0 : The device you want to connect from on the Linux host.
- 2400 : The baud rate to run at. This is the ‘speed’ of the serial line.
- vt100 : The terminal emulation mode to use. VT100 is quite a basic mode.
So, we now have a login box on the CPC. I log in using my usename and password, and i’m prompted with my shell prompt!
Next, we have to connect to a Viewdata system. After a brief google, I came across CCL4.org. CCL4 is based in Hull, North Humberside in England
On my ‘Viewdata terminal’, I typed in the following telnet connection string
To sign up for CCL4, I was greeted with the next screen. Once I supplied some details, I was in!!!!
There are some strange pages on this site. For example, info about Noel Edmonds…
This short clip below will demonstrate what 2400 baud is like.