8
Adding sound
The ZX-HD currently does not have sound over HDMI.
Separate analog sound
Many TV’s have the option of adding analog sound to an HDMI signal separately by a 3.5mm stereo
mini-jack input socket. Check your TV’s manual to find out if your TV has this function.
If so, you can use a mono or stereo mini-jack (some ZX Spectrums have a modified stereo output or
external stereo soundcard such as the ZX-AY) to stereo mini-jack cable.
Adding sound using external speakers
Of course a great solution to add sound to your ZX Spectrum with ZX-HD is by using an external set
of speakers.
Almost all speaker sets have a stereo plug. When using a mono audio output on your ZX Spectrum
(such as the MIC socket), this may result in only hearing the audio from one speaker.
To solve this, you will need to use something like an adapter cable or modify the speakers cable.
Firmware upgrades
There are two types of firmware on the ZX-HD:
The CPLD chip in the ZX-HD circuit boards
The firmware on the micro SD card for the Raspberry Pi Zero
Firmware on the micro SD card for the Raspberry Pi Zero
To know which firmware version you are currently using, simply boot up your ZX Spectrum with ZX-
HD and check the ZX-HD boot screen.
At zx-hd.bytedelight.com you can find the latest firmware version for the firmware on the micro SD
card, including upgrade instructions.
The CPLD firmware
The CPLD firmware won’t change quickly.
It’s not possible to upgrade the CPLD firmware without additional programming hardware.
ByteDelight offers a CPLD firmware upgrade service in case there is a potential future CPLD
firmware upgrade that creates new features.
If there is a new CPLD firmware version, it will be listed at zx-hd.bytedelight.com, including more
information about the CPLD firmware upgrade service.
Customizing HDMI output settings
It’s possible to modify the configuration of the ZX-HD by editing the configuration files on the
included SD card.
The HDMI color output can be set by the user, with the choice of a vivid color set (default), or one
that is calibrated to composite video output of the ZX Spectrum, or a custom set of colors.
More information is found in the
cmdline.txt
file on the micro SD card of the ZX-HD.
The
config.txt
file on the micro SD card of the ZX-HD can be changed for these settings:
-
To stretch the video output to the dimensions of your display, e.g. 16:9
-
To remove the small black border around the video output (this may however result in pixels not having
exactly the same width or height)
