Xtal BASIC Course Disc

This is the disc image the site's Xtal BASIC course is written against. Mount it in MAME, type XBAS at the DOS prompt, and a few seconds later BASIC says Ready. It is equally useful on its own if you want to try the Einstein's own BASIC and be able to keep what you write.

What Is on It

• XBAS.COM, TATUNG/Xtal BASIC 4.2, exactly as it came on the Einstein's System Master disc.
• The nine BASIC programs Tatung shipped in 1984, with the menu that runs them: Introduction, Einstein, Clock, Othello, Mastermind, Hangman, Keyboard, Picture Pen and Snakes, and the two word lists Hangman chooses from. LOAD "DEMO" and RUN for the menu, or load any of them and LIST it.
• GAME, the game the course builds, finished: Mouse In A Hole. See below.
• XC.COM and XR.COM, the Xtal BASIC Compiler 5.10 and its run-time system, from Xtal's own X-Master disc, and GAME.XBI, the finished game compiled with them. XR GAME at the 0: prompt runs it, twice as fast as in BASIC.
• 64K of free space, which is where your own programs go.

Why It Is an .mfi and Not a .dsk

This matters more than it sounds, and it is the reason this disc exists.

MAME will not write to a .dsk image. It will read one perfectly well, so BASIC starts and runs and everything looks fine, until you save a program: on a .dsk, SAVE answers Bad Data Error, which says nothing about the real cause. The course has you save your work at every stage, so a disc you cannot write to is no use for it. The .mfi format is MAME's own flux-level format, and MAME does write to it, so anything you save is still there next time.

If you want the disc as Tatung sold it, that is here too, as the TC01 System Master Disc. It is fine for looking. It is no good for working. The Einstein Disc Tools will convert between the two formats in either direction.

Using It

Put the file somewhere you can find again and point MAME at it:

mame -rompath ~/roms einstein -flop1 ~/einstein/xtalbasic.mfi -window

The Einstein boots to TATUNG/XtalDOS 1.31. Type XBAS and BASIC signs on with TATUNG/Xtal BASIC 4.2 and Ready. SAVE "NAME" keeps your program on the disc, LOAD "NAME" brings it back, and DIR lists what is there. DOS takes you back out.

Three things worth knowing before you start, all of which stop people dead:

• In MAME no key stops a running program. Put IF KBD<>0 THEN STOP inside any loop so that a key press stops it, and save before you run anything new.
• Minus is SHIFT and =. The key marked with a minus types an underscore, and PRINT 7_2 is a Syntax Error. " is SHIFT and 2, : is the ' key, and + is SHIFT and ;.
• Some ordinary words cannot be variable names. BASIC finds its own keywords inside them, so SCORE is read as SC OR E, and TOTAL, LIFE and POINTS fail the same way.

Mouse In A Hole

LOAD "GAME" and RUN. You are a mouse on a single screen of platforms: eat all five pieces of cheese, then get home down the hole on the top platform, while two cats patrol below. Z and X walk, SPACE jumps - hold Z or X as you press it to jump that way, and once the mouse leaves the ground it goes where the jump takes it - and Q gives up. Three lives, a score, sound effects and a tune, and your best time kept in a file on the disc, so it is still there tomorrow.

It is the program the course builds a section at a time, and it is about 175 lines of BASIC. Once you have played it you can LIST it and see how it was done.

Real Hardware

If you have a real Einstein, its System Master already has this BASIC and the nine programs on it, and you do not need this download except for GAME and the compiler, which is on Xtal's X-Master disc. Tatung's own reference manual for this BASIC is archived as the Tatung Einstein Basic Manual. This image exists for emulation and for the free space. Nothing on this page has been tried on a real machine.

How It Was Made

It is the System Master with the programs the course does not use taken off: Dr Logo and its two files, the BACKUP and COPY utilities, and a stray BASIC file. Nothing that remains was altered, and XtalDOS 1.31 is still on the system tracks underneath.

GAME was typed in and saved by the machine itself, on the emulated Einstein, from the course's final listing, and locked like the rest; GAME.XBI was compiled from it on the same machine by XC. Nothing was tokenised or patched off the machine.

The disc was then tested in MAME end to end: it boots, BASIC starts, GAME loads and runs, and a program saved to the disc lists, loads and runs again after a restart. The file on this page was checked byte for byte against the tested one.