Skip to navigation


Maths (Geometry): SCALEX

[BBC Master version]

Name: SCALEX [Show more] Type: Subroutine Category: Maths (Geometry) Summary: Scale the x-coordinate in A (leave it unchanged)
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * TT103 calls SCALEX * TT14 calls SCALEX * TT22 calls SCALEX

This routine (and the related SCALEY and SCALEY2 routines) are called from various places in the code to scale the value in A. This code is different in the Apple II and BBC Master versions, and allows coordinates to be scaled correctly on different platforms. In the Master version, the only scaling routine that does anything is SCALEY, which halves the y-coordinates in the Long-range Chart (as the galaxy is half as tall as it is wide). The other routines are left over from the Apple II version, which uses them to scale the system charts to fit into its smaller screen size.
.SCALEX RTS \ Return from the subroutine