NMH BASIC

Summary

NMH BASIC Download: nmhbas23c.zip (version 1.2, 74KB) | nmhbas25c.zip (version 2.1, 90KB) | man page This is a small BASIC interpreter that I wrote in the early 1990s. For some reason I think it is one of the coolest programs I have ever written. Maybe because it is just a bit under 5K bytes large and still does something useful. Maybe it is just nostalgia. Programs Implementation Hacks and Quirks Arrays | Input/Output | Conditional Statements | Listings NMH BASIC II NMH BASIC III Programs One of the more interesting programs I have written in NMH BASIC is a variant of the well-known mine sweeper game that runs in text mode. Not just text mode, actually, but (tele)typewriter mode, as it reprints the playing field after every move. The screenshots use Viacheslav Slavinsky's excellent GlassTTY font, a TrueType font that perfectly resembles the one used in the DEC VT-220 terminal. The same font, at bigger magnification, is used in the NMH BASIC logo. What is maybe interesting about the mine sweeper clone is that it uses a stackless floodfill algorithm that stores its state in the playing field itself and needs no dynamic memory at all. I have recently described it in the paper A Stackless Floodfill Automaton (PDF, 34KB). A demo showing an animation of the algorithm is included in the NMH BASIC package. There are other programs in the package, most of them rather simple, like an implementation of the Hangman game, the (rather pointless) Nim game, a banner printer, a random number generator, etc. NMH BASIC does not have a RNG, so a 15-bit linear feedback shift register is implemented in BASIC to generate pseudo-random numbers. The first program I have ever written in NMH BASIC was the inevitable prime number sieve. I have no idea how often I have loaded and run it in the past decades - until the Floodfill demo became my new favorite. Here is the code of my first NMH BASIC program (the backslash is the division remainder operator): 10 REM 'PRINT PRIME NUMBERS' 20 REM 'M =...