THE BEGINNING:<br >This book is designed to be an<br >assewbly language programming for<br >introduction the field of machine and<br >the Sinclair ZXBO and LXSI.<br >So let us look at the way a computer operates<br >PROGRAMMER<br > T<br >TV SCREEN<br >KEYI~JARD<br >OPERATING SYSTEM<br > CENTRAL<br > PROCESSING<br > UNIT<br >What this diagram shows is that there is a barrier between the programmer<br >and the central proccessing unit of the computer. It is not possible<br >under normal programming for the progra~ner to tell the central processing<br >unit - usually referred to as the CPU - what to do.<br >In the Sinclair machines the CPU is a Z~A chip， and [ am sure it comes as<br >no surprise to learn that the ZSOA does not understand a word of "BASIC I<br >Indeed no CPU is able to be programmed in a way that is directly readable<br >by humns.<br >