Finally load the first program again by giving:

LOAD "part-a.bas"

and doing LIST. What you're going to see is the first program as you expected. You should now type:

MERGE "part-b.bas"

and then type LIST. Both programs have mixed (merged) together with line 30 being the newer one. If you had done the procedure somewhat inverted, that is part-a.bas was merged into part-b.bas then line 30 of part-a.bas would be the newest one and it would have overwritten line 30 of part-b.bas saying PRINT "Part 3a" instead of PRINT "Part 3".

Like LOAD when used on tape (drive t:), MERGE does not need a defined filespec accepting instead just an empty string ("") and will just merge the next available program. Another good use of MERGE is instead of LOAD for programs that have been saved with the LINE modifier. MERGE will just load the program without executing it thus allowing you to edit instead of trying to use BREAK to stop execution. MERGE will not work with CODE, SCREEN, LAYER or BANK modifiers. To partly simulate that functionality, there's a dot command called .extract which we will visit later on. Finally, MERGE does not work with arrays (DATA).

Using NextZXOS

Thus far, we have examined the major commands we can use to get files into the computer's memory, as well as store the contents of the computer's memory into files but with the exception of a slight glimpse into rudimentary cataloguing of files on a drive, we do not actually know how to manage the files. The following sections will cover all the facilities provided for file and folder management by NextZXOS, together with their dot command equivalents (the latter work on both NextZXOS proper as well as 48K mode and some even work on esxDOS which we'll cover at the end of this chapter). We will also examine the remaining features of NextZXOS as the system itself does much more than simple file and folder management. Let's start by examining a few concepts that are necessary in order to get a better grasp of the commands that will follow and what these do.

Wildcards

Earlier, we touched briefly on the subject of wildcards. We mentioned two characters * and ?. Their meaning is as follows:

* Any number of characters up to the end of the Name part of the filename if used prior to a dot within the filespec –and– any number of characters remaining up to the end of the Type part within the filespec if used after a dot in the filespec

? Any single character

As a note to the above, it important to remember that the type part of a filename is recognised by NextZXOS as a valid one, only if it consists of up to 3 characters. If there are more than 3 characters it is considered to be a part of the name field and the type is therefore considered blank.

You cannot use more than two * within a filespec and each * must always be the last character in its respective field (Name or Type) in the filespec, otherwise a Bad Filename 0:1 error will be returned. Below are some examples of proper and improper usage of wildcards:

These will work:

*.* Any filename with any type
* Any filename without a type
*.? Any filename with any SINGLE LETTER type