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Basic Disk Operating System BDOS handles the work of creating files on disks and of transferring data to and from disk storage. BDOS is a very sophisticated piece of software. Editor ED is used to create and modify a variety of files. The commands used by ED are a little difficult to learn. For example, +5D means delete the next five characters, +5C means move the cursor over five characters without changing anything, and +5K means kill or delete the next five lines. Once the codes for the commands are learned, however, the editor is a very powerful tool that can be used in writing and editing programs and text. Peripheral Interface Program PIP performs several jobs that are often grouped under the term utility. In general the term refers to relatively routine, unglamorous, but necessary, jobs. In CPM the utility work is shared somewhat by PIP and CCP. PIP does some of the input/output management and it also makes it possible to rearrange already existing files. Many programmers use a modular approach which involves breaking a large program into several logically related subroutines. That approach is made easier by PIP which can take several small files containing subroutines and combine them into a large single file. Dynamic Debugging Tool DDT is actually a powerful tool for writing and debugging assembly language programs. Assembly language will be covered in a later chapter. CP/M contains an assembler that can be used to write and run programs written in 8080 assembly language as well as a very good BASIC interpreter. CP/M is quite a package. === Troubleshooting Programs and Operating Aids ===There are ads in any of the computer magazines for many different types of software designed to meet a particular need on the part of the computer user. It is not possible to cover all of them in detail. Instead a few in some of the major categories will