Availability

The Chroma 81 interface is available to purchase directly from me at the following price:

• Chroma 81 interface (cased) = SOLD OUT

Notes

• SCART is mainly available in Europe; outside of Europe the use of a video format converter will almost certainly be required (note that such a converter must change the signal format, not just change connector shape).
• The interface only outputs a picture in SCART RGB format (0.7V analogue signals), which is the highest quality available via SCART (better than composite video, S-video and component video).
• A SCART cable is not included and so you must provide your own. Most commercially available RGB SCART cables will be suitable, allowing you to select your preferred length.
• The interface has been tested with 50Hz and 60Hz models of the ZX81. It does not work with clones of the ZX81 or with the ZX80.
• It is strongly recommended to use the 1.2A version of the ZX81 power supply. The original 0.7A version might not be sufficient if other devices are connected. If more current is drawn than the power supply can safely handle then it could overheat and pose a fire risk.
• The SCART output accurately reflects the picture available from the RF output. Slight shimmering or bending of the top row of the picture will be visible if it occurs in the original RF output.
• Flat screen TVs made by Panasonic do not appear to implement the SCART specification correctly and can result in the Chroma picture being shifted to the left or at worst being unstable and continually jumping horizontally. There may be other TV models that also do not display the picture from the Chroma interface correctly, but most makes appear to work ok.
• The interface is fully compatible with the ZXpand SD card interface.
• Flicker-free games originally developed for use with the ZX80 fitted with the 8K ROM upgrade may not display a perfectly stable picture due to inaccurate timings in the games. A TV tends to be far less tolerant of frame timing variations in a SCART signal than it is in an RF signal.
• The cursor joystick socket of the Chroma interface must not be used if a Memotech keyboard interface is connected to the ZX81.
• A RS232 cable is not included. If your PC does not have a built-in serial port then a USB-RS232 adapter can be used. A standard 9-way non-crossover serial cable is suitable for use with the RS232 socket, and can be used to connect to a serial printer or a PC (although note that custom software must be created to control the RS232 port).
• Modern TVs tend to struggle to display the RF output from a ZX81. However, it is usually possible to obtain enough of a picture to prove that the ZX81 is operational. You should only connect the Chroma interface to a ZX81 that you are confident is in working order else damage may occur to the Chroma interface.
• Not all SCART sockets support RGB, although most do. A TV with multiple SCART sockets might only support RGB on one of the sockets, so always try all sockets if you cannot obtain a picture.