About – Displays a NextZXOS About screen with several credits to contributors of bug reports and suggested features.

The NMI menu, uses the familiar Browser interface dialogs for loading and saving of files as needed as can be seen in the next figure.

The NextZXOS folder structure

To achieve a complete and properly booting NextZXOS the following folders and files need to be present on an SD Card:

At the root level there's the Firmware file (TBBLUE.FW) and the folders c:/nextzxos/ carrying all the drivers (RTC, Mouse etc), support programs and overlay files as well as the base CP/M image file together with the startup command file autoexec.bas.

Then there is c:/machines/next/ which contains two versions of the NextZXOS ROM (they differ in the type of 48K ROM they contain; Sinclair or Looking Glass), the NextZXOS divMMC ROM, the NMI ROM as well as the configuration file config.ini which tells the Firmware the particular settings you require for your machine.

Finally, there is c:/dot/ which contains, apart from the third party dot commands, the ones that constitute part of NextZXOS, namely: .$, .bas2txt, .browse, .browseprefs, .cpm, .defrag, .editprefs, .guide, .install, .lfn, .mem, .mkdata, .mkswap, .nextver, .txt2bas, .uninstall and .unzip.

To obtain just a booting NextZXOS you do not need the dot commands, CP/M base image, mouse driver, RTC driver or even autoexec.bas and NMI rom. Your functionality however will be limited.

NextZXOS dot commands

We have talked about dot commands, covering each one as the case dictated, but we haven't talked about what they actually are! Well, dot commands are basically an easy way to add functionality to NextBASIC (and ZX BASIC) originally invented for use by esxDOS by its author, Miguel Guerreiro. Copying from the z88dk¹⁹ documentation by Allen Albright: A dot command is loaded into an 8 K ram page located at address 0x2000, overlapping the rom, and can run without disturbing the basic system. They are launched from basic by typing their names with a leading dot, hence the name "dot command". Any string following the dot command's name is passed as a command line. On return the dot command can generate esxdos errors in the basic system, either canned ones or custom ones.

NextZXOS has extended the scheme while remaining compatible with the original specification, thus a separate set of dot commands is included with System/Next™, than what comes with esxDOS. See the esxDOS section below for more details on the differences.

The scope of this manual is a bit limited to cover dot commands in their entirety but you can visit: https://github.com/z88dk/z88dk/tree/master/libsrc/_DEVELOPMENT/EXAMPLES/zxn/dot-command to find out more about how they work and how you can write your own.

NextZXOS, apart from the third party ones included in the System/Next™ distribution, has several dot commands that perform special functions not covered elsewhere. These are:

.$ Dot commands cannot accept string arguments from NextBASIC, so .$ allows execution of a dot command accepting any parameter passed as a string thus enabling full integration of dot commands in NextBASIC

.bas2txt and .txt2bas NextBASIC is stored in a tokenised form. That means that each keyword occupies one token (see Appendix A for these values).

¹⁹ z88dk is a C-based cross-development system for a variety of Z80 compatible CPUs and systems.