![]() Program text, variables, disk buffers and the CP/M operating system itself all had to share the 64 kilobyte address space of the 8080 processor. It was often beneficial to save a program as plain text and edit it with a full featured editor. Only line editing commands were provided. ![]() Every source line was identified with a number, which could be used as the target of a GOTO or GOSUB transfer. Programs could be listed on the screen for editing, or saved to disk in either a compressed binary format or as plain ASCII text. ![]() Any line prefixed with a line number was stored as program text BASIC statements not prefixed with a line number were executed immediately as commands. Program source text was stored in memory in tokenized form, with BASIC keywords replaced by one-byte tokens which saved memory space and speeded execution. Apart from these limitations, MBASIC was considered at the time to be a powerful and useful implementation of BASIC. Since CP/M systems were typically single-user and stand alone, there was no provision for file or record locking, or any form of multitasking. MBASIC did not fully support the features of the host CP/M operating system, for example, it did not support CP/M's user areas for organizing files on a diskette. MBASIC in the uncustomized form had no functions for graphics, color, joysticks, mice, serial communications, networking, sound, or even a real-time clock function. Only the CP/M console (screen and keyboard), line printer, and disk devices were available. Unlike versions of Microsoft BASIC-80 that were customized by home computer manufacturers to use the particular hardware features of the computer, MBASIC relied only on the CP/M operating system calls for all input and output. MBASIC version 5 required a CP/M system with at least 28 kB of random access memory (RAM) and at least one diskette drive. MBasic 5.21 running on a Z80 CP/M system displayed on a monochrome monitor typical for that time.
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