Department of Electronics, who also wrote in machine code the software
needed to convert from coordinates to pulses.
Costs
The majority of the components were purchased during 1981.
Microcomputer: North Star 'Horizon' 64K with twin
floppy disks, Hazeltine 1420 VDU,
Epson printer, cables, CP/M operating
system and 'Microsoft' Basic £3,885
Coordinate acquisition: 'Datatech' rotary encoders, fitting
encoders, Soton Micro Systems interface £1,225
Coordinatograph Drive: 'Astrosyn' stepper motors, 'Digiplan'
Digidrive Unit, fitting for motors
and interface £1,325
Thus the total cost of the system at present is about £6,500 (figure
includes all taxes etc). It has become evident that a larger storage
capacity will be needed to make more advanced use of the system, and the
most likely unit to provide this will be a Winchester 51" hard disc.
It should be noted that the microcomputer system is complete in itself,
and can be used for any other purpose, when not actually recording or
drawing.
A limitation of the system is that only one function can be carried out at
a time, ie if points are being recorded it is not possible to plot.out,
and vice-versa. However, in practise the amount of time required for
drawing out is a very small proportion of the total plotting time, and so
far this has not proved to be a disadvantage.
Perhaps the biggest limitation to such a system, and indeed the hardest to
quantify in cost terms, is the requirement to write or modify one's own
software. This system is still largely in an experimental phase, and so
far only the basic software to drive the 'input' and 'output' functions
is available. On the one hand, the costs of writing one's own software
are undoubtedly high, but on the other hand the product can be tailored
exactly to fit the user's own requirements. For a specialised field such
as architectural photogrammetry, it is also unlikely that one could obtain
existing software which could be used directly, therefore the costs of
writing software would have to be met in any case.
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