8-Bit Software Online Conversion

      by Steven Flintham (15A) Introduction Accompanying this article are two programs which produce 'silly sentences'. I was reading through an old VIC-20 guide (An introduction to BASIC - part 1, for any VIC-20!) and came across a description of such a program. I decided to see if I could write such a program and this is the result. To get an idea of what the programs can do, just run either of them. Both versions work in the same way, but one should be a bit faster than the other for complex sentences. Any bias towards 8-bit machines in the example sentences is deliberate! The example sentence data supplied is deliberately fairly short and simple - just enough to demonstrate how the program works. I think the programs are fairly flexible and you could almost certainly do better. Changing the data I would advise using SentSlw for any initial experiments, since it is as fast as (or faster than) Sentenc for small quantities of data and you don't have to wait before it starts. The data is at the end of the program in DATA statments and is in two parts, the templates and the components. The templates These are the basic 'patterns' for the sentences and are just single strings. If there is more than one (as there usually will be), a template will be chosen at random. Any text in the chosen template will be copied into the final sentence, unless it is enclosed in angle brackets <>. Text between angle brackets is the name of a component and will be replaced with text according to the list of components. The last 'template' should be ZZZ to show that there are no more. The components These are the building blocks of sentences. Every component consists of three items of DATA, all of them strings. The first is its name and is the text which appears between angle brackets. Ignoring the second for the moment, the third is a list of possible bits of text. For example, a component line such as: DATA "hello","","hello~hi~greetings" will result in <hello> being replaced with hello, hi or greetings (the actual replacement is chosen at random). The tilde ~ is used to separate items i the list. If you have too many items in a list to fit on one line, you can split a component over two lines by repeating the first two items, for example: DATA "hello","","hello~hi~greetings~lots more" DATA "hello","","hi there~still more~good to see you" and this will work in the same way as if all of the items were on one line. You can use component names in angle brackets with the list of possible replacements. This sounds rather complicated, but it is quite simple in practice. For example, the following component lines: DATA "He/she saw something","","<He/She> saw <something>" DATA "He/She",,"He$She" DATA "something",,"a fox~a cat~a dog~a cow" would cause <He/she saw something> in a template to be replaced by <He/She> saw <something>, and <He/She> would then be replaced by either "He" or "She" and <something> would be replaced by either "a fox", "a cat", "a dog" or "a cow". You can have 'null' items in a list - items which are empty. For instance, the following component line: DATA "(old )","","~old " would cause <(old )> to be replaced by either nothing or "old ". Don't worry about the round brackets - they are just part of the name. I use them to remind myself that the component may be replaced with nothing. The extra space is used here so that a sentence template such as DATA "The <(old )>man sat down." can be used. If <(old )> is replaced with nothing, the space before it will separate "The" and "man", while if <(old )> is replaced with "old " the space outside the angle brackets will separate "The" and "old", while the extra space will then separate "old" and "man". This is just a technique - it is not a feature of the program, so don't worry if you don't understand it. It will become clear if you want to use it. Finally, the second item which has been ignored so far. If this is of the form S=2, it means that as well as the usual replacement, the variable S will be set to 2. Only single capital letters are allowed for variable names. For instance, the component lines DATA "man or woman",,"<man>~<woman>" DATA "man","S=1","man" DATA "woman","S=2","woman" will set S to 1 if <man or woman> is replaced by "man" and 2 if <man or woman> is replaced by "woman". Note that two extra components have to be used - this was done because usually several possible repacements for <man> and <woman> would be provided. By itself, this is useless, but if the second item in a component is a single letter (once again, it must be a capital), it is the name of a variable (as in BASIC) which will contains the item to be chosen from the list. For instance, the following component line DATA "he/she","S","he~she" will replace <he/she> with "he" if S is 1 or "she" if S is 2. If this is used without a previous component having set S, the result will be unpredictable and the program may 'crash'. A limited degree of error trapping is provided, but this is not exhaustive. If S had been three in the previous he/she example, the program would crash but it should be fairly obvious why. It would not be too difficult to provide full error trapping, but this would probably slow the program down still further. I hope that these instructions are sufficient and that you obtain at least a few minutes pleasure out of fiddling with the sentence data. If you are stuck, have a look at the example data - it contains examples of everything mentioned above. If you come up with any good sets of data, why not send your version in to 8BS? Using 80-column text If you have a Master or BBC with shadow ram, you may want to change the line reading MODE 7:width%=39 to MODE 128:width%=79 (or whatever commands are required to activate your shadow RAM). The two different versions SentSlw simply looks through the entire list of components when one is referred to. It is therefore quite slow, particularly when there are a lot of components to search through. However, the code is simpler and if you want to examine the program to see how it works, you should look at this one first. Sentenc sorts the list of components and then uses a binary search to find a component. This gives about the same speed as SentSlw for small numbers of components, but as the number grows Sentenc does not slow down too much. Both programs are a little on the slow side, but bearably so and it seems silly to spend ages speeding up trivial programs like these.    