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Appendix A

Running programs on the Model A

The programs in this book and on the cassette are supplied as versions that take advantage of the high-resolution graphics capabilities of the BBC Microcomputer Model B. Although on the Model A there will be lower resolution and fewer colours, Model A users will lose very little in terms of overall effect. The following instructions show how to alter the programs so they will run on the Model A.

All but two of the programs in this book will run on the Model A if the MODE statement at the beginning of the program we, changed to MODE 5. The procedure is as follows:

  1. To load programs from cassette use the LOAD command instead of CHAIN. So to load the program MOUNTS, for example, type

    LOAD "MOUNTS"
  2. When the program has loaded, type

    LIST 10,40

    which wall list lines l0 to 40 inclusive when you press RETURN.
  3. Find the MODE statement at line 20, or line 30 of the program. It will probably read

    20 MODE 1

    All you have to do change it is enter (next to the prompt)

    20 MODE and press RETURN.

    Now when you LIST the program you will see that line 20 reads 'MODES'.
  4. To run the program, type RUN.

Modifications for FIELD and ISLAND

FIELD and ISLAND require further modification as listed below.

FIELD

Change line 20 to read MODE 5
Change line 150 to read VDU 28,0,9,19,0
Change line 190 to read VDU 28,0,9,19,0
Change line 350 to read VDU 28,0,31,19,10

ISLAND

Change line 20 to read MODE 5.

Delete lines go and 150 from the program. The way to do this is to type at the end of the listing:

90 (RETURN)
150 (RETURN)

When you LIST the program you will see that lines 90 and 150 have been removed.

PROCSURF, the procedure giving the effect of white surf on the waves, will not operate on the Model A.


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