This two part program for Amstrad CPC micros adds a further 14 commands to Basic, in the same fashion as Xen and Xen Plus. Each line of data has a checksum, thus making it easier to locate errors. However using this system it is important to type in the listing exactly as printed. The machine code can be saved as a binary file by typing SAVE "code",b, 39000,1600The new commands are:|HELPLists the new commands.|SCRAMBLE,start address,lengthScrambles a block of memory so as to make it unreadable and thus protect it from hackers or would-be pirates.|UNSCRAMBLE, start address, lengthUnscramble a block of memory that has been previously scrambled.a$="text":|TWOTONE, @a$, colour 1, colour2This is a variation of double-height printing that allows text to be shown in two colours, giving a satisfying effect..|FLASHONCreates a spectacular flashing border effect..|FLASHOFFReverts the border to normal..|FILL,start address,length,byteFills a block of memory with the specified byte. This works very rapidly and gives a good effect when used on screen memory eg:|FILL,49152,16384,127..|LINESCROLL, rowScrolls an individual screen row to the left by one screen byte. This can be used to create smooth scrolling text..|CRT, horizontal display, horizontal sync-, vertical display, vertical sync.This sounds very technical and indeed it is. Among other things it allows the user to change the size of the screen border eg:|CRT,40,46,25,33The best effects are gained through experimentation, but if you get into difficulties |CRT,40,46,25,30 reverts the screen to normal..|BANKSWITCH,bank configuration.6128 users only. This provides an easy way of moving banks of RAM around. There are four possible configurations (four to seven). Each one moves one of the four extra 16k banks to address £4000. Typing |BANKSWITCH,0 revert memory to normal. Note, do not experiment with configurations one, two or three.PopularComputingWeekly870522
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