64 Plug-In Power

Give your Commodore true IEEE compatibility. Barry Miles on two new adaptors.

Owners of the Commodore 64 who wish to use the earlier model disk drives need an adaptor, since the C64 is designed to be used with the very slow Serial 1541 Disk Unit. Two new IEEE adaptors, the Buscard and JCL, are now available.

Usually devices like these, with the exception of the Interpod from Oxford Computer Systems, insert code somewhere into the memory of the C64. If you plan to use commerical software, always obtain firm assurances from the manufacturer that the device is compatible with those programs.

The Buscard adaptor is a sophisticated device. Set-up is different from usual: you must open up the Commodore 64, and hook two sprung hooks over the end of a couple of transistors. This is easier than it sounds, but the cautious may want to ask the assistance of their dealer. The design approach is interesting, because dip-switches are available on the top of the box, which permit the IEEE device number of the disk drive or printer to be changed from hardware. Printers are also controlled through the Buscard: either use any interface which you already have, to connect your parallel printer to the IEEE port, or use the special cable available from the importers of the Buscard, Kobra. If you are using the 1541 Disk Drive and an earlier drive, e.g. 4040 or 8050, you have two choices. Either leave them both as device 8, and reset the computer while switching the disk drives on and off. Alternatively, the manual outlines the well-known bit of Basic code needed to change the disk device number of the earlier Commodore drives, from software, which is more satisfactory.

The Buscard offers major enhancements to the C64. Firstly, it puts a machine language monitor into RAM, which is an advantage. Secondly, it also puts disk handling commands into RAM. The latest version of Buscard puts a complete version of Basic 4 into the RAM of the C64, with all the convenient disk commands in that version of Basic. An earlier Buscard, which was arguably more attractive was tested. It puts a cut-down version of the well-known Dos Support program into RAM. This gives the ability to view a disk directory without disturbing the program in memroy, including the use of pattern matching to obtain a selective directory. In addition, all the usual COPY, NEW and RENAME commands can be used. Disk error messages can be retrieved without the tedious programming which is otherwise necessary. Disk directories can be paused by hitting the space bar, which is particularly pleasant. Unfortunately, loading, and loading and running of programs are not available.

The monitor is not the latest Micromon, but has most of the more useful commands needed by the machine language programmer. The manual is quite adequate, and gives details of the memory locations used by the Buscard, and useful information on programming considerations.

The manual for the newer version was examined, and it offers additional features in the monitor: a printing disassembly, and a transfer of memory too.

The JCL IEEE-488 Bus Adaptor Cartridge is also highly innovatory. It is neat and offers one IEEE connection only, an edge connector, rather than the 'D' type favouredby the Buscard. The features provided are extensive and imaginative. A 'Mini Dos Support' is provided. The adaptor offers simultaneous use of the Serial and IEEE-488 buses, and multiuser access to floppy disk for SAVE, LOAD and VERIFY.

The left arrow key, conveniently sited on the top left corner of the keyboard, becomes a useful Soft key. It is easily programmed with even a lengthy routine in Basic which can be invoked simply. Its advantages are further extended by the fact that you can save the command to disk, and reload it merely by pressing CTRL and the Space bar together.

There is also a cunning Batch File system. For this you save the eight programs of your choice, and these are then loaded from disk and run when you press one of the function keys. The Batch System can be turned on and off by means of a simple POKE.

It is possible to boot any program of your choice on power up automatically. Merely give that program a special name. If you do not want the computer to look for this program, you hold down the stop key during power up.

A screen dump to a Commodore printer is provided. Because of possible memory conflict problems, arrangements have been made to enable you to switch off nearly all of the facilities, although the interface itself naturally must use some memory. A peculiarity of the device is a delay on power up of several seconds, while the cartridge does its thing, and there is no screen warning about why the computer seems to be hanging. However, often you will hold down the shift key during power up, which results in greater speed. You will have the basic IEEE-488 facilities, but no batch-file, DOS support, soft key, or screen dump.

All in all these are sophisticated devices, and the product of considerable thought. Both deserve to succeed.