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ComputerAnswers Column 11


COMPUTER ANSWERS NOVEMBER 1985



Copyright 1984-1989 Simon N Goodwin

PERFECT PITCH

I would be grateful for your help with a query which is driving me to distraction. I wish to be able to change the pitch on the OKI Microline 80 printer when I use it with Easyscript and a Commodore 64. I have tried GS RS US in conjuction with an escape code, but with no success. If I switch the printer on and off during print, it changes pitch from 5 to 10.

There is no problem with the printer in BASIC, when PRINT CHR$ changes pitch.
J McForland, Wendover, Bucks.

It has been three years since I last used the Microline 80, so I've forgotten the exact codes required, but you should be able to use the same codes in Easyscript as you do in Basic. The printer will always revert to its 'default' pitch - 10 characters per inch - when you turn it off and on, since it has no permanent memory for the last pitch used. You can re-select a given pitch by printing the control codes in your printer manual. This should work perfectly from within Easyscript, if you use the correct technique.

The trick is explained on page 8-10 of the Reference Section of the Easyscript User Guide. There are two different techniques, depending upon whether the signal you wish to send is a control code (a single character with an arbitrary ASCII value) or an escape sequence - CHR$(27) followed by one or more ASCII values.

From memory, you only need send one control code to change the pitch of the Microline 80. If we suppose that the effect you want is given by CHR$(15) in Basic, you get the same effect by defining a special character (section 8.2.11.2 of the manual) with that code. To make special character 2 correspond to CHR$(15), you put this unlikely- looking sum into a format statement:

2=15

From that point onwards you can insert a CHR$(15) into your text by pressing F1 and 2. A reverse-video '2' will appear at the point where the CHR$(15) will be sent. Bear in mind that the word-processor does not take control codes into account when formatting (it doesn't know enough about printers), so you will probably need to adjust the margins to keep text in a mixture of styles neatly formatted.

You can set up ten different control codes, by substituting digits from 0 to 9 in place of '2' in the above example, and entering appropriate ASCII values on the other side of the equals sign. This should be enough to bring all the features of the Microline 80 under control, without bothing with the more complicated 'Escape Sequence' instructions in the next section of the (rather confusing) manual.



BEEFING UP THE BEEB

I have been told that it is possible to add more RAM to the BBC Model B by way of a paged RAM system. Are there such ways to increase the user RAM in a BBC model B computer, and what will be the proper specification for such auxiliary RAM boards or paged RAM boards? Where can they be bought and how are they fitted? What is the name and address of the BBC Computer User's Club and their magazine?
Finn Olsen, Drammen, Norway.

You can expand the memory of the BBC Model B by fitting 'sideways' memory - the memory appears at the addresses normally used by add-on ROMs, and the mechanism used to alternate between ROMs is persuaded to switch between 16K 'pages' of RAM instead. Access to the extra RAM is slightly slower than to the normal 32K, due to the need for switching.

The memory is commonly used to hold the display information (which can require up to 20K on the BBC Micro) so that all of the standard 32K can be used for programs and data. In practice a few kilobytes are used by the Beeb's operating system, but you do gain all the space previously used for the screen picture. This is especially useful if you use the Beeb's memory-hungry 80 column display. Software supplied with the memory makes the computer use sideways RAM in this way automatically.

A popular make of Sideways RAM is the 20K Aries B20, from Aries Computers of Milton Road, Cambridge, CB4 4BH. Twillstar Computers, of 17 Regina Road, Southall, Middlesex UB2 5PL, market a similar product called the Raven 20.

Watford Electronics, of 33 Cardiff Road, Watford, offer a 32K expansion which works in much the same way - the extra 12K can be used as a printer buffer, so that you can carry on using the computer while documents are being printed. Solidisk Technology, of 17 Sweyne Avenue, Southend on Sea, Essex, produce a range of expansion cards offering up to 256K of sideways RAM.

All of these boards plug into ROM or processor sockets on the BBC Micro circuit board - they are supplied with fitting instructions. If you wish to use the memory with specific software or add-on hardware, you should contact the suppliers to make sure that their memory is compatible - some programs and devices are not compatible with sideways RAM.

In general these expansions are only useful if you have software to suit them. You can't run Basic programs in sideways RAM, for example, so if your code needs more than about 28K you'll probably have to buy a second processor - these come with 64K of memory, of which about 46K is available to Basic.

There are dozens of BBC Micro user clubs, catering for all sorts of specialised interests - the largest is Beebug, which can be contacted via PO Box 109, High Wycombe, Bucks. The club magazine, also called Beebug, is published ten times a year.



THE RIGHT CONNECTION - 1

Is there any way I can download data recorded on a Psion Organiser into a Commodore 64? The data I have in mind will need to be loaded into Superbase for processing and subsequent printing out. Could you tell me how I go about it?
S.G Norsted, Woburn Sands, Milton Keynes.

Your best bet is probably to connect the machines via RS-232 interfaces. This can be a tricky process, so you should consider re-typing the data unless you really need to transfer information between the computers on a regular basis. The RS-232 interface is likely to be your best bet. Psion can supply an interface for the Organiser.

The Commodore 64 has a built-in serial interface but this does not use RS-232 protocol, so you need a converter to get the machines talking to one another. Be wary when purchasing an adaptor for the 64, since the 'reception' side of RS-232 is generally the trickiest to get right; some cheap adaptors are really only designed to transmit information to printers. Any RS-232 interface capable of driving a modem should work with the Organiser.

You may need to fiddle around a little to get the machines talking. Make sure that both devices are using the same speed - it is probably best to start with a slow speed, like 300 baud, and try to increase this once communication is underway.

Both machines should use the same 'protocol' - this is the number of bits per character, parity, and the number of 'start' and 'stop' bits used to delimit each character. So long as you use at least seven data bits and the same delimiters and parity at both ends of the line, all should be well. A good initial setting is eight bits, no parity, one start bit and two stop bits.

If things don't work at first, this may be because both computers are 'talking' at once. Serial interfaces generally use a four-wire 'handshaking' system. Two wires convey data in each direction, and the other two indicate that each machine is ready to receive data. The term 'handshaking' originates from the way that the devices alternately signal their readiness to communicate.

The RS-232 system is bi-directional, but the naming convention assumes that one device is 'in charge' of the conversation. When you connect a computer to a peripheral such as a printer this is not generally a problem, since most peripherals let the computer take charge. But when you connect two computers you run the risk that both will try to talk at once - in effect, they will both send data on the 'data out' line, when the 'slave' machine should transmit on the 'data in' wire, so that the names make sense at the 'master' end.

If this is your problem you will need to reverse the connections at one end of the cable. You may have to consult the people who supply your equipment to find out how to do this - some interfaces (such as the one on the BBC micro) use a 'reversable' connector, so that you can swap the wires by turning the plug over.

Tyepro Ltd supply adaptors called 'gender changers', which save you the hassle of re-wiring cables; they sell a suitable RS-232 interface for the Commodore 64, and are willing to make 'custom cables' to order. Contact them on 0223 322394. If you get stuck, you should find Psion helpful - their number is 01 723 6919.



THE RIGHT CONNECTION - 2

I have a Sharp MZ80K and an Amstrad CPC464. I would like to get them to 'talk' to each other without affecting any other Amstrad expansions - printer, disk drive, speech synthesiser etc. I am not planning to expand the Sharp any further.
G Vine, Stockport, Cheshire.

In theory it would be possible to interface the computers via their cassette ports, but machine code software would also be needed on one or other machine so that the 'alien' protocol could be decoded. Unless a reader who has cracked the problem writes in, I would suggest that you avoid this alternative and opt, once again, for a so-called 'standard' RS-232 link.

You will need an RS-232 interface for both computers. An interface for the Sharp is available from Peterson Electronics (0307 62591). A number of firms produce RS-232 interfaces for the Amstrad, but some of these interfere with future expansion of the system, as you suggest. By the time you read this Amstrad should have produced their 'official' RS-232 unit. I'd recommend this in preference to the others, since it should be fully compatible and widely available - it also adds an extra 32 commands to Amstrad BASIC.



COMPUTER TUTORS

I have an 18 year old daughter who is educationally handicapped and a very slow learner. I have heard that computer teaching programs are commercially available. Where can I find a list of these?

I have am eight month old Dragon micro but do not know of any suitable programs and thus realise that it may be necessary to purchase another micro. What is the best way of buying a second-hand computer - avoiding the pitfalls and bearing in mind that I am not technically minded?
S Grattage, Wednesbury, West Midlands.

It is impossible to give specific advice about educational software without knowing the details of your daughter's disability. You will find advertisments for educational software for the Dragon in specialist magazines such as Dragon User, but - as you say - there is not much about. Touchmaster used to offer some excellent educational programs for the Dragon, in conjunction with their graphics tablet, but they seem to have ceased trading.

If you decide to change machines you should bear in mind that your Dragon will not fetch much on the second-hand market - you'll be lucky to get £50 for it. The Acorn Electron and the Sinclair Spectrum are probably the best machines to replace it with, since there is a good deal of educational software available for both.

The main advantage of the Spectrum is the sheer size of its software catalogue, which includes excellent programs for almost every conceivable purpose, along with a vast amount of utter rubbish - caveat emptor! The Electron scores on the quality of its keyboard and built-in programming facilities, but it was never a best-seller.

If you shop around you can buy these machines, new, for under #100. At that price it is probably not worth buying a second hand machine - unless you can find reliable technical advice the element of risk involved will probably outweigh the price-saving.

Educational software for the Spectrum is plentiful and cheap. Electron software is a little harder to obtain, but many packages for the BBC Micro, a recent favourite with schools, will also run on the Electron. Prices are a little higher but there is less rubbish. In both cases you should be able to obtain software from large stores - W H Smiths, just off Corporation Street in Birmingham, carry a good range for both machines.

Many 'entertainment' programs have a great deal of educational potential. You may find that simple 'adventure' games and simulations offer have more educative value than 'drill and practice' routines which are still, regretably, as common on cassette as they are in the classroom.



THE END OF THE LINE

My system consists of a Sinclair ZX Spectrum with Interface 1 and microdrives, connected to a Juki 6100 printer with a serial interface card.

Word-processing with Tasword 2 works well, but I am unable to obtain satisfactory program listings. The Juki has a maximum printing width of 11 inches, or 110 characters using my daisywheel. If a program line consists of more than 110 characters the printer does not generate a line feed until the end of the program line. This means that every character after number 110 is printed at the same print position. Have you any suggestions?
George Jessen, Sunderland, Tyne and Wear.

You're not the only one with this problem - I ran into the same snag when using the Juki with a Dragon computer, although in that case I was able to solve it by telling the computer to insert a line feed after a certain number of characters. POKE 155,N sets the line width to N, but this trick only works on the Dragon and Tandy Colour Computer.

I don't think the Juki is clever enough to wrap lines for you, so you will need to take some action at the Spectrum end of the link. If you were using a Kempston Centronics printer interface you could impose a fixed line-length with a POKE, as on the Dragon, but this only works with interfacing software loaded from cassette. It would be quite expensive to put Centronics interfaces at both ends of your printer cable.

Another option is to alter your programs so that they don't contain such long lines. This can be done largely automatically. A program called Supercode 3 (from CP Software, 0532 694504) contains a simple utility which break Basic programs down so that each line contains only one statement. This may leave a few long PRINT statements to be edited manually. Supercode contains more than 100 other 'utility' routines, and runs happily from microdrive.

If you are prepared to do some programming yourself, you could get around the problem by LISTing your Basic to a microdrive file. Read the lines back one by one into a string variable, and print them to the RS-232 piecemeal. Your program can insert line feeds after each section of a line. This process will not be very fast, but you wouldn't have bought a Juki if you were a speed freak!



AMSTRAD LITERATURE

A few months ago I purchased an Amstrad CPC-464. I would like to know about a book that explains the machine's capabilities better than the manual.
Ali Imran, Lahore, Pakistan.

I don't know of any 'easy' guide to the Amstrad which is worth buying - this is probably because the manual supplied with the machine is quite good from this point of view - at least by the standards of other micro manuals. I suspect that you are after more technical information.

The 'Concise Basic Specification' is heavy going, but a good source of information about the inner workings of the machine's 'Locomotive Basic'. The 'CPC-464 Firmware Manual' is rather better reading. It contains general details of the system which would be of use to a machine-code programmer. Both are available from Amstrad, at a rather hefty price of £20 each. If you want to delve into the intricacies of the disk system the 'DDI-1 Firmware Manual' should be your guide - it costs £10, again from Amstrad at 169 King's Road, Brentwood, Essex CM14 4EF.



HIDDEN PROBLEMS

I am using an IBM-PC compatible with a 10 Megabyte hard disk, running MS-DOS version 2.11 Is there any way to delete a hidden file from the hard disk without re-formatting it? The hidden files are from Microsoft's WORD program.
Paul Michaelidis, Athens, Greece.

You will not be surprised to hear that the information you need is hidden in the DOS manual. Hidden files are distinguished by a bit set in the 'attribute' byte of the file control block. You can change this from machine code with a call to CHMOD - MS-DOS function-call number 46.

If your software experience does not extend to systems programming, have no fear! A program to do the job (and many others besides) is included on the 'Norton Utilities' disk, which was produced to accompany Peter Norton's excellent book, 'Inside the IBM PC'. The program you want is called 'file hide' - it is equally proficient at making hidden files visible.

The book and the disk should be available from large bookshops. Unless you have a good local supplier you may find it easier to order it from the author, phoning a credit-card order direct to California - the number is (213) 399 3948.



HAS TANSOFT FOLDED?

Does anybody know what has happened to Tansoft Ltd? This sister company of Oric was reported to still be trading after Oric went to the wall. Tansoft was known to be moving as both companies shared offices. However, nothing has been heard from Tansoft since February, and Oric Owner magazine has not appeared since Christmas. British Telecom has no record of their new number and the printers of Oric Owner can't find them either! Where is Tansoft? Do they still exist?
Ian Harvey, East Barnet, Herts.

This is just one of a stack of letters that have come in since Oric went bust early this year. So far as I have been able to discover, Tansoft still exist - at any rate, they have not been liquidated. There again, they seem to be lying extremely low at the moment, which does not augur well for those who are owed money by the firm. I suspect that all is not well at Tansoft; 'Sherlock' Kewney is now investigating the situation.


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