Chapter 2
11
Setting up the interface
Before handling the SPECTRA interface it is advisable to touch a grounded metal
object to ensure you are free of static charge, e.g. external bare metal section of the
casing of a plugged in desktop PC. The board should then only be held by its edges
to reduce the risk of electrostatic discharge damaging the circuitry.
The SPECTRA interface is mounted on four plastic legs, one per corner of the board. If
not already fitted, these must first be attached. Each leg consists of a plastic bolt and a
plastic pillar. To attach a leg, push a bolt through a mounting hole from the top side of
the board and screw it into a pillar held underneath the board. The bolt can easily be
tightened by hand, but a flat bladed screwdriver may be used if preferred.
The SPECTRA interface should be connected to the Spectrum using the following
procedure:
Ensure the television and the Spectrum are both powered off.
Plug the SPECTRA interface into the Spectrum’s expansion port. If you wish to
connect other interfaces then the order in which they are connected becomes
important (see the section below entitled Connection order for details).
Plug one end of the SCART cable into the SPECTRA interface and the other
end into a suitable SCART socket on the television.
Power on the television.
Power on the Spectrum.
The SPECTRA interface generates all necessary signalling voltages into the SCART
socket to inform the television to automatically display the RGB signal, and so there
should be no need to manually select the mode (unless your television does not
implement this feature of the SCART specification). It may take a few moments for the
television to detect the mode signalling and switch to display the SCART socket input.
The video signal absent indicator will light when the SPECTRA interface is powered
on but should almost immediately switch off and remain off. The condition under
which it may remain on is described in Chapter 3.
Connection order
The SPECTRA interface can coexist with other peripherals attached to the Spectrum,
but the order that these peripherals are connected becomes important if the SPECTRA
interface has the onboard ROM or ROM cartridge facility fitted and any of the other
peripherals contain their own ROM or support a plug-in ROM. This is because all
ROMs must share the same address space and as a result only one may ever be
active at a time. If there is only a single ROM based device connected (SPECTRA or
other peripheral) then the order of connection is unimportant.
A peripheral wishing exclusive access to the ROM address space can instruct all
devices connected in front of it to relinquish control. However, it cannot signal such a
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