RD Digital Tracer
The following review
was taken from Crash 6 July 84
The tracer consists of a double jointed arm with a cross hair sight at its end. The knee
joints contain potentiometers which detect in combination with the supplied software, the
exact location of the hair cross in reference to the tracers base. The tracer interface
unit does not inspire confidence, in fact the enclosure is constructed out of a standard
cassette box and certainly doesn't reflect the high cost of the unit. Nevertheless the
tracer performed immaculately throughout the test and proved reliable.
The tracer can reach a maximum tracing area of 300 x 300mm using automatic scaling, but
the normal area is 256 x 176mm for normal draw mode. The base is fitted in position with a
clamp or with the double-sided adhesive strip supplied. A template is provided for
positioning the tracing sheet grid in the correct location. The interface of the tracer is
plugged into the back of the Spectrum (with the power supply disconnected !). The software
cassette DT2 is loaded and the system is ready.
The cassette contains five program:
DRAW. All general purpose draw features including outline paint and copy.
SCALE. The drawing is transferred to screen scaled up or down, reversed left to right and
RETRACE. Stores a string of drawing commands and co-ordinates for later retracing. In
practical terms this means that it stores an outline drawing which can be recalled
GRAPHICS. Sets up an array of user defined graphics.
COMP. Comp 48 includes all four above programs. Comp 16 includes Draw, Scale and Retrace.
The RD DIGITAL TRACER runs rings around the usual drawing utilities with and without light
pens. The tracing arm is definitely more easy and accurate to use than a light pen.
However its application lies not in sketching and freehand drawing, but is limited to
copying or tracing of existing drawings. The extra features of Scale, Retrace and Graphics
increase the efficiency of the system and makes it the most versatile tracing utensil on
the market. The only drawback is the price of £55.50, which makes it a rather expensive
Spectrum add-on, and limits its application to the serious or well off Spectrum owner.