Dr Logo Course Disc

This is the disc image the site's Dr Logo course is written against. Mount it in MAME, type LOGO at the DOS prompt, and you have everything the course needs. It is equally useful on its own if you simply want to try Dr Logo without hunting through a full System Master.

What Is on It

• LOGO.COM, Dr Logo 1.20, the interpreter itself.
• SKETCH.LOG and QUIZ.LOG, the two Dr Logo programs Tatung shipped on the Einstein's System Master. Both carry the same byline: written by David Wess, dated 15 October 1984, copyright Tatung (UK) Ltd.
• About 128K of free space, which is where your own programs go.

Nothing else. The System Master's Xtal BASIC and its ten BASIC demonstration programs have been removed, which is what makes room for your work.

Why It Is an .mfi and Not a .dsk

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

MAME will not write to a .dsk image. It will read one perfectly well, so Dr Logo loads and runs, and everything looks fine until the first time you type save. Then you get a disc error that says nothing about the real cause, and your work is gone. The .mfi format is MAME's own flux-level format, and MAME does write to it, so anything you save is still there the next time you start the machine.

Dr Logo is an interpreter. You type your procedures in at the ? prompt and keep them with save — there is no separate editor and no file on your PC to fall back on. A disc you cannot write to makes the language close to unusable, which is why the course ships an .mfi.

If you would rather have a .dsk for some other purpose, the Einstein Disc Tools will convert this file in either direction.

Using It

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

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

The Einstein boots to TATUNG/XtalDOS 1.31. Type LOGO and wait — Dr Logo takes the best part of a minute to load — and you get a ? prompt. From there, dir lists what is on the disc, save "name keeps your work and load "name brings it back.

One thing worth knowing before you start: there is no square bracket key on the Einstein. Dr Logo puts them on the arrow keys, left for [ and right for ]. Pressing an ordinary bracket key does nothing at all and gives no error, which stops people dead on their first repeat.

The Two 1984 Programs

They are worth your time. load "sketch then sketch runs a five minute guided tour: a pattern of nested triangles, a face that smiles, a histogram with a pie chart, a steam locomotive, spiral patterns and two sine waves. It asks your name partway through and uses it to say goodbye at the end.

load "quiz then quiz gives you a menu and two ten question general knowledge quizzes, with scoring, retries and a jingle.

Both are plain text, so once loaded you can read them with pots and po and see how somebody at Tatung solved these problems in 1984.

Real Hardware

If you have a real Einstein and a System Master, you do not need this download — Dr Logo and both programs are already on that disc, along with everything else. This image exists for emulation, and for the free space.

How It Was Made

Built from a Tatung System Master image by removing every file except the three above, then converted to .mfi with the site's own Einstein Disc Tools. It was made by stripping a working System Master rather than by creating a blank disc, because Dr Logo is an ordinary CP/M program and needs XtalDOS underneath it to do anything with a disc at all.

It was then tested in MAME end to end: the disc boots, Dr Logo loads, dir lists the two programs, a procedure saved with save reappears in the directory, and load "sketch brings in all nineteen of SKETCH's procedures.