APPENDIX A TO SECTION 4
KNOWN BUGS AND THEIR REMEDIES
1. Monitor Connections
2. Known Bugs
3. Printing Problems
4. SER Outputs
5. How to Cure a Crashing QL
6. Flickering Displays
1. MONITOR CONNECTIONS
1.1 You may have been experiencing difficulty in getting an adequate performance from a monitor connected to your QL. Given below is a revised
set of wiring instructions for the connection lead. These instructions replace those given in page 31 in the Concepts section of the QL User Guide.
1.2 Monitor Connections. A monitor may be connected to the QL via the RGB socket on the back of the computer. Connection is via an 8-way DIN
plug plus cable for colour monitors, or a 3-way DIN plug plus cable for monochrome. The RGB socket connections are as in the following table, and
the column indicating wire colour refers to the colour coding used on the 8-way cable and connector available from Sinclair Research Ltd. Pin
designation is as shown in the diagram attached.
1.3 A monochrome monitor can be connected using a screened lead with a 3-way or an 8-way DIN plug at the QL end. Only pins 2 (ground) and 3
(composite video) need to be connected via the cable to the monitor. The connection at the monitor end varies according to the monitor but is
usually a phono plug. The monitor must have a 75 ohm 1V pk-pk composite video non-inverting input (which is the industry standard). Both 3-way
DIN plugs and phono plugs are commonly available from audio shops.
1.4 An RGB (colour) monitor can be connected using a lead with an 8-way DIN plug at the QL end. The connection at the monitor end varies
according to the monitor (there is no industry standard) and is often supplied with it. A suitable cable with an 8-way DIN plug at one end and bare
wires at the other end is available from Sinclair Research Ltd.
1.5 A composite PAL monitor, or the composite video input on some VCRs may work with the QL. Only pins 2 (ground) and 1 (composite PAL)
need to be connected via a cable, to the monitor or VCR.
Diagram of Monitor Connection Viewed from the Rear of the QL
Pin Function Signal Wire Colour Signal Level
1 PAL Composite PAL Orange 1V pk-pk into 75 ohm
2 GND Ground Green
3 VIDEO Composite Mono Video Brown 1V pk-pk into 75 ohm
4 CSYNC Composite Sync Yellow 0 to 5V TTL (active low)
5 VSYNC Vertical Sync Blue 0 to 5V TTL (active high)
6 GREEN Green Red 0 to 5V TTL (active high)
7 RED Red White 0 to 5V TTL (active high)
8 BLUE Blue Purple 0 to 5V TTL (active high)
2. KNOWN BUGS
2.1 There are a number of bugs still alive in the QL. Some are rather obscure, but here is a list of the ones that could cause a customer to return a
QL as "faulty", together with the clue you should look for when you suspect a bug is the real problem.
1. If you delete a procedure which was at the end of a program and then call the same procedure from the keyboard, and then call CLEAR, the
QL may crash.
Clue: Computer crashes after CLEAR command.
2. "LIST" within a program can cause various unfortunate states, e.g. "not implemented".
Clue: "LIST" within a program.
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