Powerbase Shareware Database

The latest version of Powerbase is v.9.72 which incorporates a few minor changes and bug-fixes from v.9.70 whose description follows.

It's been a long time since a new version of Powerbase appeared and some people might have concluded that the program is no longer being developed. This is far from true; many changes have been implemented in the last couple of years and here at last is v. 9.70. The three major changes from previous versions are as follows:

• The separate versions suffixed DA and SH no longer exist; there is now just one Powerbase suitable for all versions of RISC OS from 3.1 onward. It detects which RISC OS version is being used and loads an appropriate library to support either the sliding heap (for RISC OS 3.1) or dynamic area handling (for RISC OS 3.5 or later).
• The user no longer needs to invoke index balancing or shun data entry in key-order. A new, self-balancing, type of index has been introduced which keeps the indexes reasonably balanced at all times.
• The number of usable subfiles has been increased from 6 to 16. I know many users never need anything but subfile 0, but cataloguing something like a photo collection or a collection of newspaper cuttings is greatly eased by being able to split the data into a number of separate categories.

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.

• 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 or later; v.9.52 recommended.

• 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 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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