Powerbase Shareware Database

First of all something which has nothing to do with Powerbase! A new section devoted to interactive fiction (text-based adventure games) has been added to the website. So far it contains just one item: the completed RISC OS version of The Mirror of Khoronz, a game written originally for the BBC micro and offered by a number of PD sources. This is a vastly expanded and enhanced version of the game taking advantage of the facilities available in RISC OS.

The main development in v.9.42 was a radical overhaul of the resources for customising a database. The demonstration in custom/zip (see Download area, Miscellaneous downloads, Customising Powerbase) was completely rewritten to add non-trivial features to the !Elements database and gives a much better idea than formerly of what can be achieved. Efforts have been made to provide facilities making it much easier for users to incorporate such fundamental features as menu-creation, text output to a window, scanning a database subfile and providing interactive help. The HTML documentation for Ch 15 of the Reference Manual has been greatly expanded to describe these improvements. Please note that there has been an important change in the method used to report events such as database opening, record loading etc. from Powerbase to a customisation library and the array special%() is no longer used for this purpose. !Sudoku and the customised version of !Elements make use of these events and need at least Powerbase v.9.44 (see below) to run.

The latest version of Powerbase is v.9.45 which has two new features:

• The minor feature is the addition of a menu button to the label-printing dialogue to enable selection of the standard Avery label sizes. Appropriate settings of sizes and margins are then implemented automatically.
• Of more importance is the additon of a new item to the menu displayed over a windowed report. This new item is Print and enables users to create reports in a window for inspection, then print them (using the current printer setup settings) by simply clicking MENU over the window and choosing Print. It also works with all types of ancillary information which can be displayed in a window, such as keystroke equivalents and details of fieldtypes.

Only the DA variant of 9.45 is yet available. 9.44SH will follow in due course. v.9.45DA is suitable for RISC OS 3.5 or later. v.9.44SH is suitable for all versions of RISC OS from 3.1 onward. Version 9.44 is a "tidied up" version of 9.41 with several minor bug-fixes, changes to text in windows and menus and a new way of informing customisation libraries of certain events. Most of these have been made alongside the preparation of the new user manual which is described below.

The difference between the DA and SH versions lies only in the way in which they manage their memory requirements. 9.44DA makes extensive use of dynamic areas, a practice now deprecated in some quarters. Nevertheless, this is the version I recommend to all users of RiscPC, A7000, Iyonix etc.
9.44SH uses instead the sliding-heap module (as have all versions of Powerbase prior to 9.00) but this module has now been made 32-bit compatible.

• type in a Sudoku puzzle then "fix" it so that only the blank squares are editable thereafter. (The puzzle can be "unfixed" if you made a mistake when entering it!)
• set about solving the puzzle by filling in the blanks. "Illegal" entries will be disallowed.
• click a Help button to tell you what numbers are allowed in the current square.
• reset the puzzle to its initial state if you make a mistake.
• solve the whole thing automatically (but you don't really want to do that, do you?)
• generate new puzzles automatically.
• merge puzzle into an Ovation Pro document at the click of a button. Print the puzzle on paper, with or without the addition of numbers which could go in each blank square.

Get !Distrib from the Download area. Requires Powerbase v.9.44.

• a list of chapters
• individual contents lists at the start of each chapter
• an alphabetical index

PbaseDoc can be run from the new Help button on Powerbase's iconbar Info window, provided that PbaseDoc and your web browser have both been "seen" by the filer. The very limited Helpreader text incorporated in previous versions of Powerbase has now been removed along with the menu entries which invoked it.

The PDF documents were prepared from the Ovation Pro versions.There are no plans to produce Impression versions of the new documents.

The sliding-heap module was written by Steven Haslam in 1992. It creates and manages any required number of memory blocks at the top of a program's Wimpslot and allows them to be resized, scrapped and re-created at will. Because increasing the size of a block is achieved by moving up blocks at higher addresses, and shrinking or destroying a block results in the "hole" being closed by other blocks sliding down, memory fragmentation is avoided.

The module has now been upgraded to make it 32-bit compatible. Visit the Download area to obtain a copy of this module for use in your own programs, along with extensive documentation, a library of BASIC routines for accessing the module's SWIs and a demonstration of the module in action. Thanks are due to Christopher and Harriet Bazley for undertaking this work.

Powerbase is shareware. Registration costs 10 GBP, payable by cheque to Derek Haslam.
You may register by credit card through APDL.

The printed Manual, with Supplement and Tutorials booklet, (costs 5ukp, not downloadable!) covers versions through 8.33 (updated May 2001). These items are printed from the Ovation Pro documents described below.

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