Sharp MZ-800 User Manual

3.1 Introduction
Your MZ-800 has been encoded with a set of instructions that allow it to perform a variety of opera-
tions, such as accepting a command entered by you from the keyboard. This set of instructions is called
the monitor program or simply the ‘‘monitor’’, and is stored in ROM (*). Any computer needs input
from a human being to know what operation to perform next. After you power on the MZ-800 the
monitor program makes the MZ-800 wait for you to input a command. Depending on the key you
press, the monitor allows you to perform one of the monitor commands, or reads a larger set of in-
structions from an external memory device, such as the data recorder, and places it in RAM (*).
*: ROM and RAM are memory devices which store information for the computer. The ROMs (Read
Only Memory) contain memory which can be read but cannot be changed or removed, even if the
power is turned off. The RAMs (Random Access Memory) however, contain memory which can
be both read and written. The MZ-800 uses ROM for storing the monitor program, and RAM for
temporarily storing the BASIC interpreter, BASIC programs and data, and other information. The
BASIC interpreter is explained in this chapter, while the monitor will be explained in detail in Chapter
8.
All the commands you input to your computer must be translated into the computer’s own language,
called machine language. Machine language consists of a collection of binary digits, which makes it
extremely difficult for most people to understand. Luckily however, you need not worry about learn-
ing to understand machine language, since the BASIC interpreter does this for you. BASIC is a “‘high-
level’’ language system which is similar to English and much easier for us as human beings to under-
stand than machine language. The BASIC interpreter reads instructions written by you in BASIC and
interprets them into the MZ-800’s machine language.
If you press the [ce] key when the initial frame is displayed, the monitor loads the BASIC interpreter
into RAM from the cassette, the BASIC interpreter then begins operating. (‘‘Load’’ means that infor-
mation is read from one memory device, e.g., the cassette, and is placed in another memory device,
e.g., the RAM.) Instructions written in BASIC are called commands or statements. The BASIC inter-
preter displays the following frame after the BASIC interpreter has been loaded.
BASIC interpreter 12-016 VX.XX
Copyright(C) 1984 by SHARP CORP.
XXXXXbytes free
Ready
.
(blinking)
This display indicates that you can use the computer interactively, i.e., when you type in a command,
the computer responds. If you type an incorrect command, the computer will answer with an error
message.
Each command evokes only one response from the computer, and multiple commands are difficult
to connect in a sequence. Because of this, you cannot get the computer to perform complicated opera-
tions in the interactive mode. The solution to enable the computer to perform complicated task, is
to write a program and store it in RAM. A program is a series of statements which are automatically
interpreted by the BASIC interpreter. A program which can be interpreted by the BASIC interpreter
is called a BASIC program.
3-2

Sharp MZ-800 Specifications

General

Brand	Sharp
Model	MZ-800
Category	Desktop
Language	English