The 'Classic' G. Dixon NBTV Test Card.

[Steve Anderson]

For some time I have being trying to get my hands on the original of this very familiar card as a raw listing. Recently I was made aware that a hex listing is in the newsletter Vol.21 No.3. So armed with this (see below) I created two files, a .tiff version and a raw hex file.

The .tiff file displays on a PC monitor with the incorrect aspect ratio as PCs assume all pixels are square, which here they're not. But it should prove useful in establishing an approximation of what grey levels you see on a monitor. You will need to zoom it significantly, in Irfanview a factor of 800% (x8) is useful without any interpolation effects from the software.

The raw hex file is exactly that, these are the values you blow into an EEPROM or the like, I've just saved you the tedious task of entering 2048 hex values!

There are 64 pixels per line, 4 are for the blanking/sync period and the active video part is 60 pixels. At 64 pixels/line requires a clock frequency of 25.6kHz to produce a 400Hz line rate. The sync itself is not included, in the original article it was generated in hardware.

I have no way of confirming the pixel values in the .hex file are correct, the line and file size appears correct but a few of the pixel values might be a bit 'off, the scan isn't that clear in places.'. If anyone should come across this please let me know where the error is (line number should be enough) and I'll correct it and re-post here.

I hope this is useful...

Steve A.