Nascom News­let­ter

The Winchester Disc

Winchester discs differ from the more familiar floppy disc drives in that their mode of operation is quite different, and the storage medium is sealed in the drive unit rather than being removable. Because the disc operates is a sealed environment, with no variation in the storage medium, the speed of access can be far faster than with a floppy disc, and the capacity is also much greater. At the present time we are offering three versions of the Winchester disc – 5M byte, 10M byte and 20M byte versions. These contrast with the 375K bytes of a single sided floppy disc and 750K of a dual sided disc. The disc is controlled by the computer in a different way to the floppy disc, and therefore a different controller card is fitted in the computer. This replaces the normal floppy disc controller but also provides a floppy disc controller on the same board. There is also a high speed communications facility on this board for use in networking or other applications.

The Winchester disc with its large storage capacity and fast access will be of particular interest to the business user with large data files, and to users of networks. Support for the Winchester disc is available through both the NAS-DOS and CP/M disc operating systems. In the case of CP/M the Winchester is incorporated in the system by running a special program (automatically if you wish), while in the case of NAS-DOS the Winchester version of the operating system should be specified when ordering.

The NAS-DOS Disc Operating System

NAS-DOS is the disc operating system used by Nascom computers which provides compatibility with the simple tape operating system. A range of applications software and system software is availble, generally best described as cheap and cheerfull. None costs more than £70, and while lacking the sophistication of some of the more expensive programs for the CP/M operating system they have the considerable advantage of being easy to use and fast in operation. NAS-DOS was the first disc operating system released by us for the Nascom computers, and has always been the most popular. A new release of this operating system, Rev 2.1, is under test at the time of writing, and will be available by the time this article appears in print.

As in previous updates to NAS-DOS the latest release is fully compatible with previous versions, and represents refinements to the existing product rather than a major new development. While a special offer will be made to existing registered owners of NAS-DOS to allow them to upgrade to the latest release, we would suggest that for most people there will be little advantage in doing so. Details of the special upgrade offer will be released in the next issue of the magazine.

The changes incorporated in Rev 2.1 of NAS-DOS are as follows:

1. Standard version supports 6mS track to track disc drives – the half-height units now being used by Nascom. Special versions of the operating system to suit older, lower speed, drives can be supplied to order.