SINCLAIR ZX SPECTRUM

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You can type the lines in once, in a form known as a subroutine, and then use, or call, them anywhere else in the program without having to type them in again. You want to get one called something along the lines of "Z80 Machine code [or assembly language] for the absolute beginner", and if it mentions the Spectrum, so much the better. The printer buffer stores the characters destined for the printer. Small integers have a special representation in which the first byte is 0, the second is a sign byte (0 or FFh) and the third and fourth are the integer in twos complement form, the less significant byte first. Other errors possible, as for VAL - number Negation The following are binary operations: + * / = > < <= >= <> Addition (on numbers), or concatenation (on strings) Subtraction Multiplication Division Raising to a power. Everything that an INPUT statement writes goes to the bottom part of the screen, which acts somewhat independently of the top half. PLOT INVERSE 1; OVER 1; - this leaves the pixel exactly as it was before; but note that it also changes the PLOT position, so you might use it simply to do that. The loudspeaker is sounded by using the BEEP statement, BEEP duration, pitch where, as usual, 'duration' and 'pitch' represent any numerical expressions. 0<=|m|<=255, 0<=|n|<=175, else error B POKE m,n Writes the value n to the byte in store with address m. You could make a chart showing the pitch value for each note that you can play on this instrument. When it is at 255, the next increase takes it to 0, and at the same time it nudges PEEK 23673 by up to 1. Now the computer has displayed the result and is waiting for another number. Use Gauss' law of quadratic reciprocity to show that 75 is a primitive root modulo 65537. It also tells you in what circumstances the report can occur, and this refers you to Appendix C. As an example, the elements of the 3*6 array b in Chapter 12 are stored in the order b(1,1) b(1,2) b(1,3) b(1,4) b (1,5) b(1,6) b(2,1) b(2,2) b(2,6) b(3,1) b(3,2) . RANDOMIZE n (with 1n65535) makes b equal to n+1. A PRINT item can also be nothing at all, which is a way of explaining what happens when you use two commas in a row. Other errors possible, depending on the expression VAL$ string Evaluates x (without its bounding quotes) as a string expression. i i The ZX Spectrum uses p=65537 and a=75, and stores some b -l in memory. Now type 30 (and ENTER) This time, the program cursor is hidden after the end of the program: and if you press EDIT, then line 20 will be brought down