The BBC and Master Computer Public Domain Library

ALPS (ADVENTURE LANGUAGE

PROGRAMMING SYSTEM)

Professional, ROM Chip Expansion

Instructions

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Review (Electron User) - "Climbing Icy Mountains"

The Electron version of ALPS - Alpine's Adventure Language Programming System - has recently been converted from the original BBC Micro program. Alpine says, "Necessity being the mother of invention, we have actually squeezed in more features than the BBC Micro version has".

This adventure creator package includes a 16K ROM, User Guide, keystrip and either disc or cassette of utilities and sample adventures. As ALPS is a ROM-based utility, you will need either a Plus 1 and blank ROM cartridge or a ROMBOX. To evaluate the system, I converted my QUILLed adventure RELUCTANT HERO into ALPS.

An adventure program created by ALPS in made up of a list of rooms and objects, along with the program logic to handle them. The object and room descriptions and properties are stored in easy-to-use tables.

Up to 150 objects, and 255 verbs and synonyms can be defined. Each room and object has eight flags and a state value. Memory is set aside for them at the start, unlike THE QUILL, where the more objects or verbs you use the less memory there is available for the game.

Any object can be a light source and all or just some of the objects can be breakable, magnetic, heavy or sharp. The object's flags can be changed in the logic part of the program so that a blunt knife can be sharpened.

The object's state can be linked to messages so that a knife could be described as "A long jewelled knife with a sharp edge", "A long jewelled knife with a blunt edge" or "A long jewelled knife with a broken blade".

To save memory, the "A long jewelled knife with a" is the same in each instance, with the alternatives tagged on depending which switch is active in the object description.

Another memory-saving device is the hash symbol. Whenever it appears a predefined message is placed at that point. Any number of hashes can be used to reduce the text.

The technique can be used for the 150 possible locations, and any room can be designated as airless, flooded, poisonous and so on. The room state can be used to alter the description.

Automatic text formatting ensures that words are not split over lines so there aren't any worries about how messages appear.

Text compression must be done manually and I found this difficult to do effectively. Efficient automatic text compression is available on the extras disc or tape. It took about one minute to compress all the text in RELUCTANT HERO.

The optional extension disc allows you to produce large adventures by holding all the text on disc. Games can then have up to 255 locations. With the extras disc you can compress the text by up to 60 per cent.

Also, more predefined verbs such as GET ALL and DROP ALL are added, and a container is provided in which objects can be placed or removed. These verbs can be programmed using ALPS, but the Extras disc does it more efficiently.

A special starter program provides verbs like TAKE, DROP INVENTORY and the directions.

Standard movement is N, S, E, W, UP and DOWN, though you can program the game to accept any other direction, but at a cost - the more non-standard directions used the more memory will be needed to program them.

A useful feature is that each room has an exit routine for each standard direction, allowing you to have a conditional exit like a locked door or secret passage.

Before the player is moved the exit is checked to see if there is a special routine for it, and if so whether it allows movement at that time. If it doesn't then the player isn't allowed to proceed and a message can be given explaining why.

Automatic exit reporting is enhanced compared to the BBC Micro version. Every time a room is described ALPS looks at every connecting room and reports that "There are exits north to MSG and south to MSG" where MSG is the text in the room data table.

There are one 50 integer variables, compared to 64 in THE QUILL, but there are also eight On/Off flags and one state with a value of up to 255 for each object and room.

This leads to one of the problems of ALPS - trying to debug the logic. With THE QUILL the game can be run with all of the flag values displayed, but ALPS would have to display 2,700, which is not feasible.

Most of the familiar adventure keywords are present, but sometimes different words are used. Some common keywords are missing, among them are CLS, DROP, GET and PAUSE. However, DROP and GET are defined in the special Starter file, which means you can redefine how they react to a particular situation. Instead of printing OK you could have different messages for each object - memory permitting of course.

PAUSE can be programmed by using procedures. The delay is easily set by making the program loop a number of times. I found the loss of CLS to be irksome, but as I became more used to ALPS I found I didn't miss it as much.

All the flags can be set to zero or one wherever you are, so an action in one room or on one object can change the flag in another room or object. The state of an object or room can be incremented or decremented so allowing progressive changes.

Whole sentences can be typed by the player and either the first recognised verb and object can be acted on, or by extra programming, the whole sentence can be analysed and acted upon.

The on screen editor used in entering the logic part of the program is only a simple line editor rather than a full screen version. The function keys are used to enter the object, room and text editor as well as for inserting/deleting lines and text compression.

The utilities allow you to create standalone games that can be run without the ALPS ROM, print the room and object data lists and the text.

You can also examine two sample adventures, one small one with seven rooms and six objects, and a larger one with 50 rooms and 90 objects. You can play both of the games and access the data files so that you can see how they have been constructed.

The User Guide is a 38 page booklet which is, for the most part, easy to understand, though I felt the section dealing with writing the logic part of the adventure was not basic enough. The rest of the sections were well explained, particularly the one on sentence analysis.

ALPS is superb value for money and well supported by Alpine whom I found very helpful whenever I stumbled.

Paul Waterman, ELECTRON USER 6.11