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H: Third Party Products    

The following information concerning 512 specific products or services is provided in alphabetical order. Unless stated to the contrary all products or services listed are believed or known to be of good quality and reliable. However, you must judge for yourself the suitability of any given product for specific tasks or applications.

Beebug Ltd.

Beebug deserve mention not only as a supplier of hardware and firmware products for the BBC micro, but because they are now the only publisher of a magazine which is exclusively dedicated to the 8 bit BBC micro family, including its various co-processors. While other magazines have effectively transferred their allegiance to the Archimedes, Beebug instead choose to produce a cornpletely separate Archimedes magazine while continuing to publish the BBC micro magazine in its original form rnaintaining its original objectives.

A regular feature of Beebug magazine is 512 Forurn written by Robin Burton. This column, which is exclusively devoted to the 512 and related matters has been a feature of the magazine every month since mid 1988. From time to time additional contributions of 512 material are also included, such as reviews of 512 books and products. Sorne 512 software has also been included on the monthly readers disc.

Since other Acorn magazines have now substantially or entirely transferred their interest to the Archimedes, including only a page or two of relevance to the 8-bit BBC micro and extremely rarely even mentioning the 512, you might do well to consider taking out membership of Beebug. The magazine is published in ten issues per year and is available only by subscription, delivered direct to your home or office. A sample copy can be obtained on request and back issues are available for most items you may have missed.

Beebug Ltd., *******

Dabs Press

Dabs Press, publishers of this book, publish three other Master-512-specific items, which are two volumes of Master-512-compatible shareware, and the companion book to this one, Master 512 User Guide by Chris Snee. Full details of these are given in Appendix L.

Essential Software

Essential Software is a recent addition to the extremely limited list of suppliers of 512 products. Started in late 1989, Essential Software is run by Robin Burton and Mike Ginns (better known until now for Archimedes books and software). Essential Software's stated objective is to provide novel and useful 512 software at reasonable prices. The list of currently-available packages is extensive and is still growing.

All of the current software packages consist of several programs, including support utilities to load, configure, enable, disable or query the various modules from DOS, even for programs that actually run in the BBC host. For programs actioned by 'hot-keys' the support utilities allow user defined hot-key selection, saving and re-loading of key definitions, module suspension or deletion and the interrogation of module status and current hot-key definitions.

Many of the packages, like the command line mouse driver or the screen print, use BBC RAM and thus do not reduce 512 memory even though they're permanently resident and instantly available. All products are compatible with all versions of host and all versions of 512 DOS Plus. Where configuration may be required (eg to suit differing sideways RAM boards) the necessary programs are also included as required. All programs are loaded and controlled entirely from DOS with the exception of GoBBC/512 (See below).

In an effort to contain costs no printed documentation is supplied with these programs. Instead, all discs contain copious notes instructions, hints, tips and examples in text files which are interactively driven from a menu by simple numeric selection. The current product range is outlined below.

Ramdisc utilities

This package includes a highly memory-efficient ramdisc which uses 89K less memory than the standard MEMDISK supplied with DOS+ 2.1. Also, when a rarndisc of less than 64K is required the program reconfigures DOS's ramdrive to use 1K blocks and the directory size is reduced to 32 entries. This halves the average 'per file' losses and directory wastage compared with MEMDISK. The ramdisc may be user-configured to any size from 10K to 64K in 1K steps, and from 64K to the total memory size less 64K in 2K steps. It also can be configured as any available drive ID (ie except L:) on initial load.

Two other programs accompany the ramdisc. The first of these, AMNESIA, deletes the ramdisc without the need to re-boot the system provided that the ramdisc contains no files. If files do exist in the ramdisc the program reports an error and leaves the ramdisc intact, preventing accidental loss of files. When deleted the ramdisc may be loaded again as a new drive, or with a new size, or both as many times as required.

The second additional prograrn, DISCID, permits any drive including the ramdisc, both floppies and the winchester to be changed to any other drive ID. This program can also report on the current drive identities and has the ability to suspend any drive so that even DOS Plus can't access it. (It can, of course also re-instate the drive.) Rarndisc Utilities is supplied on disc, is available now and costs £14.95 complete.


SUPRSTAR is a replacement for the standard STAR utility. It maintains a separate virtual screen for * operations and can be called at any time, on hot-keys. When you enter the routine you see a true BBC mode 7 screen which still shows any * commands you'd issued previously and DFS is automatically selected too. On exit, achieved by pressing ESCAPE, the contents of the DOS screen from which you called SUPRSTAR are preserved as though you had never left it.

Within the * screen the machine behaves almost like a normal BBC micro, providing native facilities like standard BBC cursor editing, ESCAPE processing and normal MOS error handling.

The two greatest advantages of SUPRSTAR are that, first, commands can't destroy your DOS screen (even four colour graphics). Conversely, subsequent DOS operations don't overwrite previous * commands either, both being major annoyances with the standard program in spite of the fact that it can be called only from the command line. Secondly, as SUPRSTAR operates on hot-keys (default SHIFT-CTRL-*), SUPRSTAR can be called at any time from any package, even in the middle of loading a file if you like.

SUPRSTAR is available now on disc and costs £14.95.


GOBBC is a complementary program to SUPRSTAR, which you must have to use GOBBC. Please note this facility is impossible to implement within the extreme limitations of the standard STAR utility.

Having entered SUPRSTAR (from within a live DOS application if you wish) simply type GOBBC and you can immediately 'drop into' a completely normal BBC environment. If you wish you can directly enter any resident language, for example you might be editing in your DOS wordprocessor when you need to edit a BBC document in View prior to importing it. Just enter SUPRSTAR and type GOBBC *WORD and you're in View. Equally you can enter GOBBC on its own which will select BBC BASIC as the default language. After this you might run a BASIC program in native mode.

On conclusion of BBC operations simply enter *512 from any command line or menu to return to precisely what you were doing in DOS, exactly where you left it and as if you hadn't. Just as for SUPRSTAR, the DOS display is maintained in its existing state, nothing is lost. If you were using your DOS wordprocessor, you're still using it when you return. If you entered SUPRSTAR while a file was loading, it will automatically continue to load when you return to DOS.

GOBBC/512 is supplied on disc in BBC DFS format and is available now. The price is £14.95 when purchased with SUPRSTAR (ie £29.90 the pair) or £19.95 when purchased separately.

Printscreen Utilities

Printscreen Utilities is a package that fills a glaring gap in the 512's capabilities, one that is probably a worse omission than the absence of a mouse driver. All real PCs have a PRTSCRN key which allows a print of the screen display to be produced on demand. This is now possible in the 512, but in a much more sophisticated form than in any PC. Two screen print programs are included in the package, GRDUMP and PRTSCRN, both provide two functions, all of which actioned by hot keys and so can be used at any time from any package.

GRDUMP will print anything on your screen in any mode, though it is expected to be used mainly in pure graphics modes to give shaded printer dumps of two or four colour screen displays. The screen print is produced sideways on the printer so as to permit a large size irnage (approx 11" x 5") with no detail lost. Obvious applications for GRDUMP are immediate hard copy recording of images in art or graphics design applications.

INVERT is a second graphics option, permitting the screen colours to be inverted as they are sent to the printer so that a display which would ordinarily produce large quantities of a black or a very dark background (like GEM or Wordperfect) appears on paper as a negative of the normal image, with a white or pale background, saving both time and printer ribbons.

PRTSCRN is designed for use or in 40 or 80 column text screens to give a 'full speed' print of the screen when text or mainly text is displayed. If graphics characters are encountered in text displays, for example IBM characters, the program automatically drops into graphics mode to print the non-alphanumeric characters, ensuring that 'non-IBM' printers can handle all displays. This prograrn is invaluable for instant recording of transient screen information such as disc catalogues or hard copy recording of the help display from command line programs

The second text print facility in PRTSCRN is FAXPRINT. This is similar to PRTSCRN except that the printer's line spacing is adjusted to close up the gaps between lines which normally spoil the appearance of mixed prints of text and graphics. It is therefore just a press of the hot-keys to produce a rapid, precise hard-copy facsimile (hence the name) of mixed text and graphics displays, with box characters in particular appearing properly 'joined up'. FAXPRINT is ideal in applications for rapid recording of pull down menus which include text, virtually standard in most applications nowadays, or for printing menus or displays containing IBM box characters. FAXPRINT is also very useful for producing a compact (approx 8" x 3.5") and rapid image of full-screen graphics when the need for large scale and fine detail is less important.

Both programs, GRDUMP and PRTSCRN, are configurable for both 9 and 24 pin printers, either on loading or after installation. They are supplied on disc, cost £14.95 complete, and are available now.

Command Line Mouse

Essential Software's mouse driver, unlike a standard PC mouse driver, works on the command line (or in fact anywhere that the keyboard can be used) hence its name. It therefore provides cursor control by mouse movement in programs which normally do not or cannot work with a mouse, as well as many that do.

Command Line Mouse is not an MS mouse driver, since it takes no 512 memory and doesn't require packages to be configured to use a mouse, or even to be able to be so configured. This approach has the advantage that any program, including strictly keyboard only types, can be used with a mouse. Also the SHIFT/CTRL keys work with the mouse in a similar manner to the way they usually work with cursor keys, giving instant and super-fast scrolling. The two mouse buttons can be user-assigned to any key function (RETURN and ESCAPE by default) and the sensitivity of mouse movement in both the X and Y planes can be independently adjusted. Your chosen settings can also be saved to disc by the SAVEKEYS utilitity. The Command Line Mouse driver is supplied on disc, costs £12.95, and is available now.

Screen Save

SCRNSAVE permits any DOS Plus text or graphics screen display to be saved directly from DOS, within an application or from the command line, to either DFS or ADFS formatted discs. Defaults are provided, but the filing system, drive and filename are all user definable. A sequence identifier antomatically increments after each save to permit multiple related images to be saved without the need to change filenames.

Screen saving is triggered by hot-keys, so that any diagram or text in any package can be saved without disturbing the screen image and without access to the command line. The filename, the drive or the filing system can be changed independently as often as required.

SCRNSAVE is supplied on disc at £9.95 and is available now.

Key Translation

TRNSLATE is a key translator which allows extra keys to be defined on the Master, B or B+, or any existing key function(s) to be assigned to other nominated key(s). Definitions can include the missing numeric pad keys for model B/B+ users (or Master users if they don't like the current locations) as well as other normally unavailable IBM keys.

The keys used and the actions to which they translate are entirely user definable to the extent that you can re-map the entire keyboard if you wish. If you don't like the current key assignments in any package you can now easily change them at will. TRNSLATE costs £14.95 and is available now.

Popup Notepad

512 memopad is a 'pop-up' notepad. Access to the pad is by hot-keys, and one bank of BBC sideways RAM is required for storage, as the pad uses no 512 rnernory. whatever you're doing, press the hot-keys, make a note or two for use later, then return to the main application.

Utilities included allow the contents of the pad to be saved to (DOS) disc and subsequently reloaded. Built in commands allow the pad's contents to be cleared or printed, both requiring confirmation before execution. A simple wordprocessor-like environment is provided for the entry of data in BBC screen mode 7. Facilities include character or line insertion and deletion, plus line or page scrolling in any direction. Approximately 12K bytes of storage is provided for text (approx 4 to 6 A4 pages).

The 512 mernopad is supplied on disc at £9.35. Available now.

Miscellaneous Utilities

This is a disc containing various utilities, including:–

SELECT – a batch file menu driver which provides an interactive link between the user and batch files, giving on-line selection and operation of the options presented in batch file menus. A cut-down version of this is used on all Essential Software discs to drive our own 'readme' batch files.

COLORDEF – a screen colour changer which replaces COLOUR, allowing the screen colours to be changed on hot-keys instantly and at any time. Ideal if you use GEM, WordPerfect or any package with a glaring background. With COLORDEF change colours whenever and as often as you like.

SUSPEND – stops the 512 in its tracks. Both the suspend and resume actions are on hot-keys, so you can stop the machine while you answer the phone, get a coffee, etc, and be sure that no-one has destroyed hours of work or your files when you return (unless you tell them your hot-keys!).

LOCK – Similar in purpose to SUSPEND, but this is a command line program and is absolutely secure. You supply LOCK with a password when requested, anything you can enter through the keyboard, including control keys. The password therefore can be different every time you use it. On entry the first password is deleted from screen and after this, until the correct, and only the correct password is re-entered the machine won't react to any further keyboard instructions, including CTRL-C. When the correct password is re-submitted the program reports if illegal entry has been attempted and if so, how many attempts were made.

SOUND – a program which allows full access to the BBC micro's sound facilities from DOS – just enter the parameters exactly as you would in the BBC micro.

ENVELOPE – a complimentary program to SOUND, allowing sound envelopes to be defined from DOS. Both SOUND and ENVELOPE operate exactly as they do in BBC BASIC in native BBC rnode.

(Enhance your batch files with these two by adding varying sound effects to menu choices made through SELECT.) This disc contains 26 files including documentation and support utilities, so you'll have to buy it to find out about everything on it. The miscellaneous disc costs £11.95 complete and is available now.

Any of the last five programs, COLORDEF, SUSPEND, SOUND, ENVELOPE or LOCK may be added to any other order at a cost of £2.50 for each program. SELECT may be added to any other order for £5.95.


HISTORY is a DOS command archiver which gives options of both manual and automatic command recall. Manual recall is performed by cursor keys (or the command line mouse), allowing bidirectional scrolling through the command history. Automatic recall is based on partial command matching, when entry of part of a command instructs the program to find the nearest previous command matching the information given. A recalled command can then be edited and a further search initiated, or it can be used as the start point for further manual history examination. Recalled commands can be edited and executed as new commands, or simply repeated without amendment. By scrolling backwards or forwards through the history this program also provides an audit trail of operations performed, as well as the ability to rapidly repeat any sequence of commands with the minimum of keyboard re~entry. Used in conjunction with PRTSCRN, HISTORY can be used to provide a printed log of operations performed.

HISTORY costs £12.95 and is available now.

Additional Products

Other Essential Software products are currently planned or in development. Some are complete or nearly so, but were not packaged at the time of going to press. The list includes the following.

512 Memory Expansion

A 512K byte memory expansion board for the 512 is available. The board uses the latest chips to allow an extremely compact, low-power board with high inherent reliability. The price of upgrades supplied from the initial production batch, fitted and complete with modified EPROMS is £99.00,

It is intended that this price will be maintained for as long as possible. However, owing to the currently unstable prices for RAM (caused by the EEC's impending 'anti-dumping' duty on chip imports) and the uncertainty of the total number of boards to be manufactured, long term prices cannot be guaranteed.

A further batch of boards may be manufactured if overall demand justifies it, but if a subsequent batch is of a smaller number the price may unavoidably increase to reflect this, as the cost of chips and of boards varies inversely with the number purchased.

If you have any doubts about your ability to construct the project in the previous chapter, you might like to contact Essential first about their ready-built solution.

Other Software

A function key definer which allows user-defined commands to be assigned to the function keys. These can then be executed in DOS on a single key-press, just as they are in native BEC mode.

A file 'unerase' utility which will help you to recover accidentally deleted files (provided the file's data hasn't already been overwritten).

A file find utility which can optionally search from one to four drives for a specified file, identifying either the first or any number of occurrences of the file. A further option is to switch to the appropriate disc/directory when a file is found, or to simply display its path, leaving the current path unchanged.

A 'Fast Boot' to permit the 512 to be started up much more quickly than from the normal 640K ADFS format boot disc. Part of the speed gain is because some of the code is loaded from ROM or sideways RAM, while DOS Plus itself is loaded directly from the much faster 800K DOS Plus format 512 disc.

A hard disc partitioner, allowing any size in 1Mb units to be allocated to the two partitions.

Essential Software, *******

Interactive Software Services

Interacter from ISS is a FORTRAN development system. Users of FORTRAN in PCs or the 512 will be aware that its standard input/output capabilities are extremely limited and are very much a DIY task in many implementations. Even in more sophisticated versions of FORTRAN, such as those found on larger systems, any ready to use I/O routines are likely to be unique to the compiler in use.

The result of this is that the machine specific areas of programs, particularly screen/hard copy input/output, are not readily transportable to other systems or perhaps even between different peripherals (eg a plotter instead of a printer) since they must be re-coded by the user.

Interacter is designed specifically to overcome the difficulties of writing presentable user interfaces in FORTRAN by providing numerous ready written routines which can be called from user code to do the job for you. The technique is that, after writing your program to carry out the main processing, the results are passed to Interacter in a pre-defined consistent format simply by calling the approprate supplied library routine.

This greatly simplifies the task of producing new programs, since all that is left to the user are the main functions of the program. Peripheral interfacing such as console, printer or plotter output can be handled in a consistent manner by Interacter's ready written routines.

However, the benefits of divorcing these functions from both the hardware and the compiler are more significant than simply easing the production of new programs, though this in itself is a welcome feature.

Interacter is available for a wide range of machines. These include quite large systems such as Hewlett Packard, DEC, VAX and SUN, as well as IBM PCs using a variety of screen graphics display adaptors such as MDA, CCA, ECA, MCGA and VGA. Of interest to Acorn users, it is also produced in versions for both the 512 (using Microsoft v.4.1 or Prospero compilers) and the Archimedes (either Arthur or RISCOS using Acornsoft's release 2 compiler).

The consequence of such a development package being available for a wide range of hardware is that source programs can be much more easily transported between different systems since the I/O interfaces remain fixed. While the core functions and syntax of the language should already be either common or very similiar between different compilers, by employing Interacter the same compatibility is extended to input/output facilities.

Pricing of the package varies with the size of the system and the number of users, but 512 users will probably find the 'personal' version at £99.00 plus VAT provides all that is needed. A demonstration disc can be obtained from ISS which gives a good overview of the package's capabilities for prospective purchasers. The impression conveyed is that this is a professional and comprehensive package which should be of considerable benefit to FORTRAN users.

For a demonstration disc, details and prices of the package for the various implementations, contact Lawson Wakefield at:


Margolis & Co.

COMM+ by Margolis & Co. is a communications processor which allows the Master 512 to be used as an intelligent terminal. Both Viewdata and ANSI standards are provided, allowing full asynchronous communication with other computers. COMM+ can also be used as a comms control package with most modems, giving access to email and bulletin boards such as Prestel and Telecom Gold.

COMM+ allows the use of most modem features. It caters for split baud rates, auto dial, auto answer, and various other facilities. It also offers file transfer with full error checking to and from other computers which are runrung either COMM+ or a compatible comms package, providing a very flexible extension to the 512's capabilities. As it is the only commercial communications package which is known to work in the 512 it is particularly good news that virtually all the required functions are provided.

COMM+ also provides a built in programming language, allowing screens to be customised and foreign characters to be used. This language also offers simple database facilities and full access to the operating system for file management. The programming language is simple to use, allowing most communication links to be set up automatically and also catering for subsequent monitoring.

The documentation is supplied in an A5 ring binder that lies flat on the desk and allows pages to be removed and used separately. There is a good index to the various sections, split into the "off line tutorial" and the "cookbook". The tutorial is very good, catering for both the regular hacker using the 512 and the beginner who is new to comms. The "COMM+ cookbook" delves into the intricacies of COMM+ from starting to troubleshooting. The "reference guide" documents such goodies as the editor. This gives the ability to edit and format text before transmission. You can also save text and load documents prepared into a word processor. The editor automatically removes control codes from the text ready for transmission.

14 different terminal emulation modes are also documented in the reference guide, covering alternatives such as VT52 and ANSI standards. Kermit support is one of the many additional facilities provided by COMM+ and is also documented in this section.

The "Language Manual" documents the built in language. This is the bit for the hacker to experiment with. It offers the ability to automate and monitor communications using a logical structure. Most should benefit in some way from this facility. The software is easy to use and flexible. The manual is comprehensive and the tutorial is very good

Overall this package should prove to be flexible and capable of almost anything required. It is well worth the normal asking price, but 512 users can obtain special terms. The 512 package consists of both the 512 specific version and the normal PC version for about 20% less than the normal price of the PC version alone.

For the current price and further details conbct:

Margolis & Co., *******

Permanent Memory Systems

Permanent Memory Systems are well known for their BBC micro products, notably 'Genie' and 'Genie Junior'. However, one item in the Genie family, the 'Genie Watch' is of particular interest to 512 users who employ a model B or B+ host.

The PMS Genie Watch is an EPROM mounted on a carrier which contains an additional chip and some rather clever circuitry such that it is of a size that it plugs in to any ordinary EPROM socket. When so fitted the Genie Watch provides a permanent, battery backed real time clock of the day, date and time to B and B+ micros, giving similar facilities to those of a Master 128's real tine clock (RTC). PMS estimate the battery life of the Genie Watch is ten years, a vast improvement over the batteries provided in the Master 128.

In addition to providing additional date and time related functions in BBC native mode such as the *TIME command or 'PRINT TIME$' in BASIC, automatic date insertion in wordprocessor documents and so on, the clock also supports OSWORDS 14 (&E) and 15 (&F). The first of these is the call by which DOS reads the current system date and time during 512 start-up.

Owners of model B or B+ hosts normally either have suitable 'DATE' and 'TIME' commands in their AUTOEXEC.BAT file requesting tedious and error prone manual entry of these, or forgo entirely the very real advantages of DOS file date/time stamping. While file date/time stamps are not strictly necessary for the general operation of the system, considerably helpful, sometimes vital file information is lost if accurate dates and times are not available to reflect the most recent updates or backups of important files.

A very simple, quick modification to DOSPLUS.SYS using EDBIN is all that is required to allow automatic reading of the date and time variables from the Genie Watch during system-boot in non-Master hosts. This allows completely automatic and error free booting of the 512 without the need for manual intervention. Before starting the modification you can check full details of how to use EDBIN in chapter 11 if you are not familiar with this utility.

The modification steps for DOS Plus 2.1 are as follow:–

1.       Create a new floppy boot disc using the DISK command.
2.   At the end of formatting, when prompted confirm that the disc should be made bootable. This copies the system files to the new disc.
3.   On completion, exit the DISK program back to DOS Plus.

Set the file DOSPLUS.SYS on the new disc to read/write by the command


(These examples all assume that your system drive is A: and that the new boot disc is in dnve B:).

Load the new copy of the operating system into EDBIN by the command


This should produce a display similar to this

     size ot file = 014780 bytes
     Number of bytes read = 014780


At the '-' prompt, after EDBIN has confirmed the number of bytes in the file, enter E 795F. The display should now appear as:

-E 795F 1893:795F 75 03 E8 03 00 E9 90 F6 C6 O6 D2 1A FF B0 0E BB ................


Enter the number 90, followed by cursor right and another entry of 90. The display should now be amended to:

1893:795F 90 90 E8 03 00 E9 90 F6 C6 O6 D2 1A FF B0 0E BB ................

8.   Press CTRL-C to leave edit mode. Enter 'W' to write the file back to disc.
9.   Enter 'Q' to leave EDBIN

Note that the segment value shown in these examples may be different in your own system. This is irrelevant, as the segment number is defaulted in these commands. The amendment changes a 'JNZ 03' command to two 'NOP's. The jump is normally taken at this point in the startup procedure if the host machine is not a Master. Removing this jump therefore permits reading of the RTC date and time in all host models.

If all has been done correctly you should now be able to use the new disc to boot the 512, when you will find that the date and time are automatically set by the OSWORD &E call to the Genie Watch. If the boot fails you have made a mistake. Restart the 512 from your original boot disc and repeat the operation. You need not restart from the beginning by re-formatting the disc. Instead you can set the new DOSPLUS.SYS copy to read-write, copy your original unchanged version to it and repeat the changes from step 4 above.

On successful testing the last task is make the changes permanent. On your new boot disc reset the amended file to read-only, then set your 'real' boot disc's copy of DOSPLUS.SYS to read/write. Copy the new DOSPLUS.SYS file to the original one and the job is almost complete. (Copying the read-only file to the read-write version also changes the attributes without further use of FSET). The only item remaining is to delete the now redundant 'date' and 'time' commands from your 'AUTOEXEC.BAT' file.

The Genie Watch runs in any Model B or B+ micro which has a free ROM socket on the mother board, or on most ROM expansion boards. It will not work plugged directly into an STL 32K or 256K board, though if a mother board socket is, or can be made available this can be used successfully.

The Genie Watch normally costs £29.90 plus £1.00 P&P, but as a special offer to readers, VMS will supply the Genie Watch at a price of £24.90 plus P&P. You should mention the Technical Guide when you order to obtain this discount of over 15%.

Permanent Memory Systems are at *******

Shibumi Soft

Shibumi Soft's sole 512 product to date is a disc package called Problem Solver, the purpose of which is to remedy or reduce some of the incompatibility problems inherent in the 512 and its versions of DOS Plus.

In early versions of Problem Solver, that is up to the third quarter of 1989, although the program worked in a Master 128 it had proved extremely or entirely unreliable in other hosts, especially using version 2.1 of DOS Plus. As a result of a visit to the UK from Portugal by the proprietor these difficulties were ironed out and since September 1989 the program has exhibited a much higher and acceptable level of reliability in all machines.

It can now be said that, within the range of its capabilites, Problem Solver is a remarkable product. Since it operates effectively by patching DOS Plus, it convincingly demonstrates that with very little more effort and a little more imagination Acorn could have produced a much more 'PC compatible' implementation of DOS Plus.

Problem Solver operates by filtering program code as it loads from disc (or optionally by filtering after loading but before problems are encountered) in such a way that many of the instructions that would hang or crash the 512 are amended to a different 'special' invalid operation code.

An 'invalid opcode' error occurs when these amended instructions are executed, but Problem Solver intercepts the invalid opcode vector and so takes control when such an interrupt occurs. The invalid instruction, if known to Problem Solver, is then executed by means of legal calls. Following this the results are passed back to the calling application in such a way that it behaves as if its original (invalid) call had been successful.

The major areas in which this type of fix can assist are limited to screen display and certain types of keyboard access. That said, there is a substantial number of software titles which will not run in the 512 normally, but which will run with Problem Solver's assistance. It is fair to say that, because of the nature of the problems this package addresses and can compensate for, the majority of the listed software is games. However, it should be noted that some 'serious' packages are also included in the list, particularly those where a program's original problem concerns reading key presses rather than reading input ASCII characters.

A few additional facilities are included in the program, such as the ability to slow down the 512, presumably as an aid to playing games which run too quickly in the 512. Also there is the ability to change screen mode on hot-keys, permitting manual assistance for some packages that don't change (512) mode correctly.

For Model B/B+ owners there is also emulation of the Master's numeric keypad keys, but these are mapped onto the function keys at fixed locations which cannot be changed. This facility can be toggled on or off, but of course normal function key operations are lost when re-mapping is switched on.

A list of problem packages which this program can assist is not included here, frankly because it would occupy two or three pages. That fact in itself demonstrates the effectiveness of this product within the confines of the type of incompatibility that it tackles. Problem Solver is supplied on disc, accompanied by a limited implementation of a DOS mouse driver and a program called VISI which assists with some displays. A DOS screen saver is also included.

The price is £29.95 and Problem Solver is supplied by:

Shiburni Soft, *******

Solidisk Technology Ltd.

The PC+ is a 512K byte memory expansion board which was manufactured and sold by STL who were for some years active in the Acorn marketplace. They have however, since early 1989, entirely moved their operations into the PC market and no longer produce or sell Acorn add-ons. The PC+ was the first commercial 512 memory expansion board and during its life was produced in two versions. Note that the information here relates only to the later and more reliable version 2 and is included for those who may wish to consider the purchase of a second hand PC+.

The PC+ attaches to the 512 by means of fly leads and by plugging into the 512's EPROM sockets; the EPROMS then plug into the sockets provided on the PC+.

The issue 2 PC+ is well built and does not consume excess power (which it takes from the 512 board) hence it generates little extra heat. A Master with adequate ventilation or a fan is unlikely to have problems of overheating. If fitted to an external co-processor adaptor this should present no difficulties either. The specimen board which was tested ran in a Master 128 for two months without problems, indicating that this expansion should be reliable.

The PC+ sits neatly on top of the 512 board, adding about 2 cm to its height. The board fits easily into a Master case when the internal tube is used, or into an external co-processor box. The 'U' shaped board is supported by the EPROM sockets into which it plugs, and extends across the 512 board to the base of the 'U' where the fly leads run off to their soldered connections on the main 512 board. The cutout portion in the centre of the 'U' is to allow the 80186 to dissipate heat.

The board is sturdy and well made but it could be fitted more elegantly. Solidisk chose to cut two of the pins of a chip on the 512 board and solder to the stubs, rather than lifting the pins from the main board. This makes subsequent removal of the PC+ much more difficult, for example for repair, as the modified chip on the 512 board must be removed and replaced to return the board to normal operation for testing.

When using the PC+ a modified version of DOS Plus 1.2 can be used which takes into account all of the extra memory. This version was supplied by STL with the PC+, but was never issued by Acorn. (An unmodified version of DOS Plus 1.2 ignores the extra memory.) DOS Plus 2.1 has a modified memory map which recognises the extra memory giving 704K of user RAM with the PC+, but 2.1 will not recognise the top 256K of the expansion. This is only significant if you have a package that requires 700K pIus and DOS Plus 2.1. Since PCs and clones are limited to 640K of main RAM (ie excluding EMS) this is unlikely to present a problem. Most packages will not use anything more than 640K even if it's available. In fact Lotus 1-2-3 is the only package known to use the memory beyond 640K as standard.

The original disadvantage of the PC+ was that, since it required modification of the Master 512 board any Acorn warranty was void. However, as all purchases will now be of second-hand units it is likely the PC+ will already be fitted to the 512, which will be out of warranty anyway. So long as you see the board working reliably this point should not unduly deter you. However, prospective purchasers should note that the issue two PC+ is much preferred over the issue one version, which was neither so well made nor so reliable.

In summary, if you are able to find one the PC+ offers increased memory at reasonable cost and is a worthwhile 'add-on' if you (want to) use larger memory packages. However, bear in mind that you will almost certainly have to buy it attached to a 512, therefore the cost will effectively be doubled. (User installation is not recommended.) The final point to consider is that STL no longer supply or support Acorn add-ons, therefore the servicing of a faulty 512 fitted with a PC+ might prove difficult.

Tull Computer Services

Tull Computer Services is another recent and welcome addition to the all too limited number of suppliers of 512 products. At the time of writing Tull have just released a second 512 product which has not been evaluated, therefore only brief details are included. Their first product has however, and it is one which has been long awaited by some 512 users, an 'MS-type' mouse driver.

As mentioned in the hardware introduction in this book, for reasons best known to themselves Acorn and Digital Research jointly or severally chose not to produce a generic mouse driver for the 512, instead supplying a version which only works with the bundled GEM collection.

Cliff Bowman, the proprietor of TCS was one of the many users who felt the need for a 512 mouse driver for those DOS packages which cannot be used without one (generally art, CAD and graphics design packages) and therefore he set about producing it. The resulting program has been commercially available to 512 users since the latter part of 1989.

The Tull Mouse Driver is supplied on disc with a comprehensive manual. Although the use of a mouse driver is limited to loading the mouse program, loading an application configured for a mouse and using it, the manual supplied with the mouse driver includes extra detail which should be of interest to 512 users.

The manual begins with a short but interesting overview of the development of the mouse as a standard user interface. This is followed by details of the files on the issue disc, notes on program compatibility and a few minor limitations of the 512 implementation as compared with a mouse driver running in a true PC. One of the disc files is a README file containing the latest information on compatibility and enhancements to the program.

The bulk of the manual, the programmers guide follows. This section provides function by function details of the various calls to INT 33h, the mouse interrupt. INT 33h is not supported by the 512's version of DOS Plus as standard, hence it is not detailed in the appendices of this book, but the TulI manual provides all the necessary information for those who wish to write their own applications code to interface with the mouse driver.

The remaining sections of the manual list known compatible and incompatible programs plus 'Plug corner', containing brief details of other sources for 512 products or information.

The Tull Mouse Driver requires 5K of memory in the version tested. Although Tull actively encourage user suggestions and are keen to improve the program where possible, it is extremely unlikely it will grow beyond 6K, so even in unexpanded 512s memory usage is minimal.

At the time of writing the mouse driver does not itself provide a mouse pointer in four colour modes, partially because this would increase the program's size substantially, and partially because many graphics packages implement their own mouse pointer. However, this might limit the use of the program with some applications. The current compatibility list as supplied by Tull is shown below.





  Autoroute   Nextbase Ltd.
  Autosketch   Autodesk
  DeLuxePaint II   Electronic Arts
  Dr. Halo III   Unknown
  Elite   Firebird Software
  Flight Simulator 3   Microsoft
  GEM 3.0 and 3.11   Digital Research
  Interacter   ISS (See above)
  Mouse Cursor Designer   Shareware
  Norton Editor 1.3C   Peter Norton
  Optiks   Shareware
  PC Paintbrush   Z-Soft
  PIX   Shareware
  Reflex   Borland
  Turbocad 1.5 and 1.52   Borland
  Ventura Publisher   Xerox
  Word 4.0   Microsoft

Tull's Mouse Driver has been tested with DOS Plus versions 1.2 and 2.1 using XIOS 1.01 and 1.03. It is also happy to run with Problem Solver which, it should be noted, may be required to run some of the above programs successfully in the 512. Also, some of the packages shown will not run in an unexpanded 512.

Tull hope for feedback from users to expand the list of known compatible software, therefore readers are advised to contact Tull directly for latest information if there are doubts about any particular package. It is requested that telephone enquiries are restricted to evenings only at present, though this may change in due course.

The Tull Mouse Driver is a thoroughly competent product which, given the limitations imposed by the peculiarities of the 512 (compared with true PCs) provides an excellent implementation of a standard DOS mouse driver. At the time of going to press the price is £30.00 but readers should again check with Tull before ordering.Tull Computer Services, *******.

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