Category: retrocomputing

Matrix Rain for Atari

I haven't seen the new movie yet, but I was in a mood to do something this primitive.

  • Matriculated Rain: matrix.atr: Download, unzip, load in your Atari 8-bit computer or emulator of choice (Atari800MacX: ⌘D, select this as D1), and reboot (Atari800MacX: sh-F5). There's probably some way to ESCAPE.

It'll go into attract mode eventually, which I think is cool, add 11 POKE 77,0 to disable it. Or any key that doesn't exit will clear it.

Not any really interesting coding tricks, except I replaced POSITION:? with POKE for speed. I use PEEK(764)=255 and then re-POKE it to test if there's a waiting key, but then use GET to read it in ATASCII instead of scan code.

(updated almost immediately: I realized on XL machines I can turn on accented characters instead of graphics blocks. Take out the POKE 756,204 line if you don't like that.)

(updated 2021-12-24: I made it pour in from random starts, rather than top of screen, looks somewhat more like the old intro.)

ZX SpecNext Emulation

Half a year late, due to pandemic, "brexit", China, and redesign perfectionism (which I appreciate, but it's delaying), delayed from summer '20 into sometime next spring(?), I'm still eager to get my ZX SpecNext. So in the meantime I do emulation.

I'd played a fair bit with a ZX Spectrum emulator, but SpecNext emulation was harder. After a lot of frustration with "CSpect", which is just a pile of C# crash logs, I tried "ZEsarUX" (hereafter "Zesarux") and with a bit of fiddling, it Just Works at emulating SpecNext.

  • Download from github.com/chernandezba/zesarux, install, run. It's unsigned, so macOS security theatre: right-click, Open (do not trash!), cancel, right-click, Open, Trust.
  • Zesarux FAQ
  • F5 for emulator menu
  • Settings, ZX Vision, disable First aid help (bullshit dialogs on every interaction! You can see most of it with F1 or just waiting 10s on a menu option)
  • Settings, General, disable Window Footer (ugly & useless)
  • Back up to Storage, MMC, select tbblue.mmc, enable MMC Emulation, Paging.
  • Back up to Machine, VTrucco/FB Labs, ZX Spectrum Next, TBBlue.
  • Autoconfigure? Yes. Where? Download. I picked 512M, and tbblue-512M.mmc. Configure? Yes. I picked 60hz, x2 scaling; YMMV.
  • Just wait a few seconds, and TBBlue should transition to "Welcome to NextZXOS" (seen above)
  • Now you're at the standard Speccy menu, right-arrow will increase speed to 28MHz, down a couple to NextBASIC
  • Type in a test program, like 10 print"Hello, Mark!" (have to type ^P for ", ^1 for !, it's a Speccy keyboard, but not the one-key ZX80 keyboard), run
  • save"hello.bas" (again ^P someday that'll be wired into my fingers) and cat to make sure it's there.

Sh-1 brings up the Speccy menu.

You'll need to memorize the keyboard layout in F5, Help, or make a little reference card like I did (for another emulator, on Zesarux Esc is Break, the far right-side keys don't do anything).

The MMC file (which is a disk image that holds your files) and .zesarux config are in home dir, which I dislike but I'm not arguing with it at this point. If I mount a FAT SD card, it should read/write that and it'd be easier to move files on and off, but I don't have one I can spare at the moment. Waiting for mail-order or shopping.

Computer Lib/Dream Machines

Someone has finally uploaded a (possibly legal?) copy of to archive:

Read it from either end, there's two coherent books written back-on-back like an Ace Double, happily you don't have to turn your monitor upside down.

The first personal computer book (before the Altair came out!), though the PCC Newsletters predates it (and he mentions them). Fascinating time capsule, political tract about use of computers to control you (CYBERCRUD as he puts it).

Any nitwit can understand computers, and many do.
Unfortunately, due to ridiculous historical circumstances,
computers have been made a mystery to most of the world. And
this situation does not seem to be improving. You hear more
and more about computers, but to most people it's just one big
blur. The people who know about computers often seem unwilling
to explain things or answer your questions. Stereotyped
notions develop about computers operating in fixed ways--and
so confusion increases. The chasm between laymen and computer
people widens fast and dangerously.

This book is a measure of desperation, so serious and abysmal
is the public sense of confusion and ignorance. Anything with
buttons or lights can be palmed off on the layman as a
computer. There are so many different things, and their
differences are so important; yet to the lay public they are
lumped together as "computer stuff," indistinct and beyond
understanding or criticism. It's as if people couldn't tell
apart camera from exposure meter or tripod, or car from truck
or tollbooth. This book is therefore devoted to the premise
that

EVERYBODY SHOULD UNDERSTAND COMPUTERS.

Computers are simply a necessary and enjoyable part of life,
like food and books. Computers are not everything, they are
just an aspect of everything, and not to know this is computer
illiteracy, a silly and dangerous ignorance.

In many ways as relevant as ever. Just because you have a computer or "smart" phone, doesn't mean you know anything about its operation, purpose, and purposes you can put it to. Most people just use them as glorified TV sets and newspapers, mass media delivering people.

Unredacted 1st ed, includes some very… Ted Nelson is a white male born in the 1930s, his language about race and sex are, uh… not acceptable sometimes. Be aware.

Also, cover price $7 in 1974 is $37.61 in 2021, not $120, as Ted currently charges for a photocopy on his website. But at least he managed to publish this, unlike Xanadu which took 50 years to ship nothing.

I have a much longer draft of notes about it, that I'll probably finish up at some point. Now that I can just point you at the original, that gets easier.

Nanorogue2 in BASIC

I've completed my BASIC 10-Liner contest entry, download on itch.io

Just shove the disk (.atr) in Atari800MacX or any other compatible Atari 800XL emulator, disable BASIC and hit reset, it should boot up into the launcher:

Where you can read docs or source:

And play the game!

So, the source for my first pass was manually-packed down, and I couldn't really fit everything I wanted in there, or switch to text-graphics mode. With some rethinking, and a better source editing tool, I could… So I wrote a filter program "Basic2List.py" that removes comments & blank lines, joins up everything after a numbered line with colons, lets me insert binary codes with \xFF escapes. It still looks a little dense, because I have to manually use abbreviated statement names or remove spaces, I'd like to make it smart enough about BASIC source to do that itself.

But it lets me turn source like:

5   POKE731,1       // noclick
    GR.1            // 20x20 wide chars, 40x4 regular
    SE.1,13,15      // palette 1 to gold
    W=20            // world size
    DIME$(27),M(W,W)    // E$() encounter table, M() map
    //RRRZZZD$$..........#######>
    E$="\xF2\xF2\xF2\xFA\xFA\xFA\xE4\x04\x04\xAE\xAE\xAE\xAE\xAE\xAE\xAE\xAE\xAE\xAE#######\x3E"
    H=10        // Hit Points
    L=1     // Level
    // G=0      // Gold, default value
    ?"NANOROGUE BY MDHUGHES"

into:

5 POKE731,1:GR.1:SE.1,13,15:W=20:DIME$(27),M(W,W):E$="RRRZZZD$$..........#######>":H=10:L=1:?"NANOROGUE BY MDHUGHES"

(except the RRR... are inverse & graphics chars)

See the Atari BASIC Quick Reference Guide to learn the abbreviations and some of Atari's peculiarities. And it's running in Turbo Basic XL which really helped the program size, so I was able to squeeze in stairs!

Last time I was using the compiler, and that worked but it distorted my sounds, and I couldn't make LAUNCHER.CTB run NANOROG2.CTB! So if I just left them all uncompiled (but tokenized) .BAS files it works fine.

The only down side is it's stuck in easy mode. I'd love to have a difficulty which increases the GP to Level Up, and makes monsters hit harder (but not reward more), but that didn't quite make the cut.

Generally I'm pretty pleased by this!

The ZX Spectrum (non-Next) port is turning out to be hard, it lacks a few things and doesn't have ELSE, either, so I don't know if it can be done.

10-Line BASIC Contest

Let's go back to the 1980s!

So I knocked down a tiny subset of my already tiny BASIC demo program, NANOROGUE, and plan to make 10-line versions for Atari 800 and ZX Spectrum. Getting it running on desktop in Chipmunk BASIC was trivial. Just a little ANSI for screen positioning.

Initially I just used standard Atari BASIC, and that worked fine, if very very tightly packed, and not fast… but the lack of an ELSE statement left me with an 11-line program, I wanted to end with 50 ... :GOTO 20:ELSE:GOTO 20:ENDIF but had to move it to a new line. Very frustrating. So I'm using an enhanced BASIC, which is allowed for the PUR-120 tier, for one command.

Being "compiled" (to bytecode, don't expect miracles) and making AUTORUN.SYS easier than my own utility is nice. TBXL is at least a 1985 tool; though at the time I was using the "official" BASIC XE cartridge instead, which had similar features, and mainly moving over to Action!, 6502 ASM, and C. But for retrocomputing it's fair game.

Making a TBXL executable & bootable disk is a little fussy.

  1. Make a blank floppy ATR (emulator disk format), format it, put Atari DOS 2.5 on it or whatever you like (from DOS 2.5, H to write DOS files). This is your program disk. Like TRON, everything you do will be encoded on it, and losing it will subject you to immediate deresolution.
  2. Turbo BASIC XL disk in D1, program disk in D2. Control menu, Disable BASIC, Cold Reset (Sh-F5). You should see a red load screen, then READY. Check you're in TBXL by typing DIR.
  3. Write your program. I recommend writing BASIC as LST files in a desktop editor, then Cmd-E "Edit an atr disk image", click "Atari/Mac Linefeed Translation", "Import Files From Mac". In BASIC, ENTER "D2:FOO.LST". RUN to test it. But if you like living the '80s lifestyle all the way (or using non-ASCII chars, which are annoying to work with), you can work entirely in TBXL.
  4. Save your program tokenized: SAVE "D2:FOO.BAS"
  5. BRUN "D1:COMPILER.COM", now swap D1 and D2 (Cmd-D, click the swap buttons; you want your program disk in D1!), hit 1, pick FOO.BAS, save as AUTORUN.CTB. Swap disks back (you want your program disk in D2!).
  6. Ctrl-D, J for Ja (yes) to go to DOS-XE. COPY D1:RUNTIME.COM D2:AUTORUN.SYS
  7. Now put your program disk in D1, reset, and it should come right up into your program, then prompt for Dos, Run, or Load when it ends. Nice!


So resuming work on NANOROG, I get:

The only down side is this tiny version has a very slow redraw, it renders the entire screen each move, instead of just fixing last/new positions. I'm pondering changing it to graphics 1 (wide text, 4 colors) and poking screen memory which is probably faster than printing. I made some acceptable bleeps and buzzes with SOUND commands; I'm a poor sound designer, but I get there with some trial and error.

Anyway, next week's task is the ZX Spectrum version. Speccy BASIC is pretty good, so I expect I can knock that out quick and without all these shenanigans.

Textfiles

Looking for VT100 documentation, I found a folder of textfiles VT100 animations, including the classic Bambi vs. Godzilla.

Slightly difficult to watch on any modern computer, so save this script: (works on Mac & other Unix-likes, wtf knows what Windows does for clear and reset.)

Use: % slowblade.py ~/Downloads/bambi_godzila.txt 500

slowblade.py: [update 2022-04-18, stdin for "-"]

#!/usr/bin/env python3

import os, sys, time

def slowblade(f, spd):
    try:
        os.system("clear")
        if f == "-":
            text = sys.stdin.read()
        else:
            text = open(f, encoding='Windows-1252').read()
        for c in text:
            sys.stdout.write(c); sys.stdout.flush()
            time.sleep(1.0/spd)
        print("")
    except (IOError, EOFError):
        pass
    finally:
        os.system("sleep 10; reset")

if __name__ == "__main__":
    if len(sys.argv) == 1: raise Exception("Usage: slowblade.py FILENAME [SPEED (default 100)]")
    else: slowblade(sys.argv[1], int(sys.argv[2]) if len(sys.argv) >= 3 else 100)

Computer Archaeology: Public Caves Discovered!

Exploring the archives of the People's Computer Company (a public timesharing computer center in the early '70s, yes before home computers), and many of the programs we're familiar with from David H. Ahl's Creative Computing come from here. 15 different variations on guess the number and guess a coordinate, sure, but also some really important things, many of them long forgotten.

Then I find this artifact:

pcaves

What the. This is basically a MUD†, from 1973!

Source code (uses a very long TREES library on previous pages).

Everyone knows WUMPUS, which is based on CAVES, but this is the rock star of these! How does everyone not have a copy of PCAVES? This is like finding a working Airwolf helicopter in a cave with ochre handprints on the walls. HOW THE FUCK did cavemen do that? Why don't we all have an Airwolf, if it existed 47 years ago?!

So anyway some barely-modernized version of this will be added to the MysticDungeon soon, you'll all be able to graffiti up a cave!

† more like a MUSH ("Multi-User Shared Hallucination") with one user at a time, specifically.

  • Note: You can play a version from the Narrascope conference 2019: PublicCavesNarrascope
  • Renga in Blue typed it in for the above event, and briefly reviews it as an adventure game. Which it's not, this is a social environment, literally a MUSH.

Lost Treasure

In 1979, I learned to program in BASIC on a TRS-80 Model I. Sometime in the next year, I read one of my first programming books:

I played Monster Chase and Lost Treasure, modified them extensively, and combined them, so the cave on the island had a monster chase to reach the exit. I recall having problems getting Starship Alpha and Devil's Dungeon to work, but they joined my software library eventually.

One of my earliest and happiest programming memories was sitting at the dining room table, reading Monster Chase, and writing out a smarter movement system and obstacles in a notebook; at the time the only computers were at school, so I wrote code on paper and typed them in later.

So when I found the book again on archive.org last night, I was very excited, and had to reimplement it. I actually typed this into Pythonista on my phone with the PDF open on an iPad, only moved it to the computer to do some final cleanup and upload it.

The book suggests some modifications, and I did some minor ones: Lowered the movement error to 10%, and risk of shark attack to 10%, rising by 1.5x rather than a flat +50% each time; being anywhere near the island edge killed you too often in the original. I also don't move you out of the water automatically, that should cost a turn.

I realized in converting it that I hate, hate, hate Row,Column coordinates instead of Cartesian X,Y; tons of mainframe-era computing resources used Row,Column, and you can still see it in some APIs like Curses. Note that the original program is 74 lines, mine's 214; BASIC is a terrible language, but it's terse.

I could adapt this into another doorgame for my Mystic Dungeon BBS, but I'm not sure what the multiplayer aspect would be, and it has limited replayability without doing some randomization.