ROL (line 20) - shifts the bits left, but in rotation with the carry flag, C, removing the bit in the carry flag and placing this in the space at the rightmost bit and removing the leftmost bit and placing it in the carry flag.
LDA IM 2 load value 2 into accumulator.
Whilst such criticisms have a certain validity, this 'weakness' was in many ways the strength of the C64.Pokes as cheats In the context of games for many eight-bit computers, it was a common practice to load games into memory and, before launching them, modify specific memory addresses in order to cheat, getting an unlimited number of lives, immunity, invisibility, etc.The hexadecimal and its decimal equivalent are shown below: These decimal values can then be loaded into memory using basic, as shown below: 5 CLR 10 print CHR(147) 20 FOR D0 to 73 30 read Q: poke 8192D,Q 40 next D 100 data 169,255,141,132,3,169,200,141 110.Although one 8-bit byte can only hold a number as large as 255 (2e8 - 1 two bytes can hold a number as large as (256 x 255) (or alternatively 2e16 -1, the minus one allowing us to represent zero as ).A computer 'brain' consists in its simplest terms as the microprocessor or CPU (central processor unit, the 6510 processor in the C64, 6502 processor in the earlier Vic-20) and one or more memory banks, the two being connected by wires called buses.Each switch is thus a single binary digit or bit.Several legacy computer systems used the 6510 processor, and machine-code written on one will run on others given certain modifications,.g.
Usually we deal only with the C, Z, O and N flags.
Java, for example, compiles into byte code (virtual machine casino en ligne courses interdit code) which is an interpreted language.
If the given address is outside these limits, the C64 will report an?illegal quantity error.C64 encouraged the programmer to obtain an intimate knowledge of the computer's memory and also of its operating system kernal (i.e.Basic was often the only language available on those machines (on home computers, usually present in ROM and therefore the obvious, and simplest, way to program in machine language was to use basic to poke the opcode values into memory.904: 11000000, C.Dave and Laura Yearke, "Turbo basic Command Set", Western New York Atari Users Group.This is harder than it sounds in assembly language, since the result has to be stored in two bytes, since the largest value that can be stored in one byte is 255.Such modifications were performed using poke statements.