TIMELY FOR EXPERIMENTS
GLANMIRE Electronics of the Republic of Ireland has produced a realtime clock and eight-bit I/O port for the Spectrum or ZX-81. The crystal-controlled clock is battery-driven and is re-charged when connected to the computer power supply - a maximum of 4Oma according to the booklet.
It is set to compensate for various months but not leap years. It can be adjusted by a screwdriver control on the board to go faster or slower. A 256-byte PROM mounted on the board provides the software to read and write to the clock from within Basic and the time is returned in a Basic variable called T$.
It provides a good basis for experimenting but at a cost. It is also incompatible with most other I/O equipment for the Spectrum, as it uses all the spare addresses. The board provides a full ZX-81-type extension at the back for a RAM pack. It might be useful with some applications which require an accurate, independent clock as part of time-keeping systems, such as accounts control or data logging.
From Glanmire Electronics Ltd, Meenane, Watergrasshill, Co. Cork, Ireland, the clock and I/O ports costs £40 for the Spectrum version and for the ZX-81 version £36. They are not interchangeable.