Aids to good tape use from Hilderbay
HILDERBAY, which specialises in business programs, has produced three products for the tape user. The first and easiest to use is a level meter which allows you to LOAD the programs at a constant level and to identify tape defects, such as sudden changes in level.
The second is a book which explains how to get the best from your tape recorder and even hints on which one to buy. It also contains some very good tips on loading "unloadable" tapes. The third is a test tape which can be used to tune your tape recorder to its peak. That means that you may have to use a screwdriver but that is nothing to the confidence it gives you to know that it is not your tape recorder causing the problem.
All the products are first-class and very easy to use. The meter costs £5.95, the book £2.90 and the tape £4.90. Hilderbay also sells a tape recorder aligned and tested for £24. All prices include VAT and are post free. Hilderbay is at Regents Park, London.
ZX BUSINESS systems produces three products for housing the ZX-81. One stand houses the ZX-81, notepad and printer on the top, with the ZX-81 and RAM pack clamped to prevent wobble. On the lower level a tape recorder and cassettes can be stored. The unit measures 14in. x 10in. x 4in. and costs £17.50 inc. VAT.
The other two are cases, one made from birch plywood and the other in ABS plastic. Both hold the ZX81/RAM/tape recorder securely. The plastic version costs £35 - 16¾in. x 13in. x 5½in. - and the wooden one £27.50 - 20½in. x 13in. x 5½in. - from ZX Business Systems, Isle of Wight.
A DEVICE called the Software Protection Unit will supply battery power for up to three hours on a basic 1K ZX-81 and 1.5 hours with the 16K RAM pack, Microbyte says. It will also stop crashes or errors due to mains fluctuations by using "high-speed detection and switching circuitry". What it consists of is two battery holders for AA cells - you supply the batteries at £3.34 per set - in a black box with a jack socket to take the power supply plug at one end and a power supply plug at the other.
The unit costs £8.60 inc. VAT and postage. It can be obtained from Microbyte, Staffs.
A WOODEN case made from birch ply is available from Kalenia Wood Products. There are models for the ZX-81 and the Spectrum. Both hold computer, manual, printer and RAM encased in plastic foam ready for use.
The cases cost £21 for the ZX-81 version, which can contain the printer or the tape recorder, and £22 for the Spectrum version, which also has space for the Microdrive. Kalenia Products is at Stoke-on-Trent.
THE OZ CONNECTOR is a strong aluminium box which contains a switch for controlling the cassette leads on your tape recorder for the ZX-81 or Spectrum. It will allow you to listen as a tape is being loaded and to speak an introduction to the program on tape. It requires no power supply and is robust. It has a built-in amplifier but has a socket at the side to disconnect the internal speaker and connect it to an external amplifier.
At £18 it is more expensive than the Abacus offering at £14.95. The OZ connector is available from J Incledon, Somerset.
Above: Memopak Centronics interface
MEMOTECH has produced a Centronics parallel interface for the ZX-81. It enables the user to use a proper paper printer to list from a ZX-81. The printer, however, will not print graphics, except with the hi-res pack fitted, or inverse characters. It changes all the inverse letters to lower-case and gives a code C error if invalid characters are used.
Control characters, which can produce double-width characters are available by prefixing a letter with an inverse dot. The commands are used are the ones in Basic - LLIST, LPRINT and COPY. A 2K ROM is included in the pack to do the conversion from Sinclair codes to ASCII, which the printer uses. A high-quality product but with limitations, the Centronics I/F costs £41.90 inc. VAT and postage from Memotech Ltd., Oxford.
KEMPSTON Electronics now has a port which will work on both the ZX-81 and the Spectrum. It is I/O mapped and is operated by address bit 7, so it is free of any expansion by Sinclair. It has an 8255 interface chip which gives three ports programmable for input or output.
The output at the top of the board is via a 28-way PCB edge or DIL sockets and edge connectors can be used to connect the equipment. The 8255 presents a very light load on the data and address lines, which is a good idea. It requires either a mother board - £16.95 - or a stackable connector - £5.50 - to user it. It costs £16.50 plus 70 pence postage for one and £1 for two or more items.