SB BBC @ GBR Oldie hints/tips #196-198 Hints and tips from the archives of Wakefield BBC Micro User Group... 196. Making the most of VIEW (4) ~~~~~~~~~~~~~~~~~~~~~~~~~~~ View has 26 number registers which are labelled A to Z. All of them can be set from within the document but two are used by View to hold the page number (P) and number of lines (L). To set a register press and enter SR followed by and then the register and the number you wish to set it to. For example SR A 20 which would set register A to a value of 20 Printing out number register values is achieved by placing their symbols (A to Z) after either the DH DF CE RJ or LJ commands although they must be preceded by the symbol. For example LJ L would print out the number of lines in the current page DF //Page P// would print the page number each time a footer is printed Instead of a number you can use an expression such as A=A+2, which must be entered as SR A A+2 Not the most exciting of the View facilities although the value L (number of lines) is useful when placed at the bottom of the document and in conjunction with SCREEN, used to show how many lines of the page are left. ie SR A 66- L LJ A where 66 is the page length Finally if you have a Master then D and T are not available as they are used for printing the date and time respectively. de Andrew G8YHI 197. Disc hint ~~~~~~~~~ If you are using discs that have previously been formatted on a 40-Track drive, you can sometimes have problems using them on an 80-track drive. Theoretically, this shouldn't happen, but apparently it does. The cure is to 'wipe' the disc using a bulk eraser electromagnet, or a powerful permanent magnet, and then reformat it. This same technique is also useful when saving files onto 40T discs using a 40/80 switchable drive set to 40. If the disc has previously been formatted and used on a true 40T drive, wipe the disc with a magnet first and reformat it as 40T on the switchable drive. The files should be copied off this disc as soon as possible, and then the discs reformatted on a true 40T drive. 198. High-density floppy discs ~~~~~~~~~~~~~~~~~~~~~~~~~ From time to time, you may come across 5.25" discs referred to as "High Density". After "Single", "Double" and "Quad" density, you may be fooled into thinking that "High" density must be a good thing. Think again! Single, and double density discs, whether single or double-sided, single or double-density, 40 or 80-Track, tend to be made on much the same production lines. After testing, the best discs can be certified as 80T (96 tpi) double-sided double-density, and lesser ones as perhaps single-sided, or single-density, and so on. Obviously, manufacturers cannot conveniently arrange exactly the right failure rates to achieve the exact mix of quality of discs required to satisfy the demand, so quite often discs are of better quality than officially certified. Quad density discs tend to be made on separate production lines, and are of higher quality. Nonetheless, they are basically made of the same materials, and it would do no harm to use them if they were cheaply available. High-density discs, on the other hand, are a very different thing altogether. They are intended for systems which pack 1.2 Mbytes onto one disc, (usually superior IBM compatibles), and the magnetic material is different. A crude comparison might be that between ordinary ferric audio cassettes and chrome cassettes. A much stronger magnetic field is required to magnetise the material properly, and only drives intended to do this are suitable. They sense whether the disc is 'ordinary' or high-density, via an extra notch, and alter the head current accordingly. What this boils down to in practice, is that High Density discs can be very unreliable and unpredictable when used with 'ordinary' drives such as one has connected to a BBC Micro. Frequently, they do not even format properly, or if they do, funny things happen later. In other words, DO NOT USE THEM!! The situation with 3.5" discs is similar, though apparently many modern drives normally used in a double-density mode will happily cope with high-density discs. This applies to later Arcs, though I am not sure about the earlier 440s amd 300 series. However since High Density discs are VERY expensive, there seems little point in finding out! 73 Rick G4BLT @ GB7WRG