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.

Programming the Atari 8-bit

My programming started in 1979 with the TRS-80 Model I, but in late 1981? early 1982?, I got my Atari 800, and later a 1200XL, then Atari ST. Those are what I consider "my computers".

Last few weeks for hobby time, I've taken up playing with an Atari 8-bit emulator, and may soon buy an old machine (130XE? I guess?) and a modern SD-card reader, and HDMI adapter unless I want to set up my old CRT… Yes, this is "pointless", but it's the most emotionally rewarding programming I've done in some time.

Had to do a lot of setup to get to this point, though. Follows are my excessive notes, which will hopefully be useful to others.

The keyboard mapping in AtariMacX is weird, I finally figured out:

Mac Key Atari Key
` Break
F2 Option
F3 Select
F4 Start
F5 Reset
Sh-F5 Cold Boot
Opt-F5 Insert Char (be REAL DAMN CAREFUL not to miss the Opt key!)
Sh-Opt-F5 Insert Line (same, DANGER WILL ROBINSON DANGER)
Home / Opt-F7 Clear
End Atari/Inverse
PgDn / Opt-F10 Help (XL/XE)
Opt-F1 F1 (1200XL)
Opt-F2 F2 (1200XL)
Opt-F3 F3 (1200XL)
Opt-F4 F4 (1200XL)
Capslock Cycle caps, may take several tries of caps A backspace repeat until you get lowercase, not graphics or uppercase.
Sh-Capslock Uppercase, almost always works

Typing on a real Atari keyboard is probably the #1 reason to get real hardware instead of emulation.

Immediately it comes rushing back, how much I didn't like the default environment of blue screen, clicky keyboard, inset margins. Easy to fix with a few pokes, but I don't want to do that every time I reboot, so I need a startup program.

  • First, configure Atari800MacX with the subdirectories next to it. It comes with all these folders in user space, but it's actually mapped to somewhere in /var, which is awful.
  • Make a boot disk. Media -> Disk Image Conversions -> XFD to ATR, pick the DOS25.XFD image in OSRoms, and call that boot.atr, store it in Disks, Load it in D1 Cmd-1 and pick boot.atr.
  • Reboot into DOS, by Control -> Disable BASIC. Bask in the glory of Atari DOS 2.5.
  • Make a data disk, Media -> New Floppy Image, I went with Medium Density (130K) since almost everything can read that, assign to Drive 2, and call that disk2.atr or whatever.
    • From Atari DOS, Format: I <return> D2: <return> Y <return>
    • Preferences -> Boot Media -> Set to Current Media, Save Configuration
  • My Atari BASIC project on Gitlab
    • Based on what I remember of my old main menu, I had a ton more stuff but I'm slowly adding routines as I need them. This can also be a shell for new programs, delete 11-9998 and use the subroutines. I wrote Draw to test joystick & function key scanning, not to be a good paint program, typed in a Music demo to make sure I had sound working.
      • Digression: This is not an efficient structure, because high line numbers take longer to find; an optimizing Poindexter would put the subroutines tightly packed at 1-999 and the program at 1000+, but it's massively easier to read & work with this way. I won't be in BASIC that much anyway, it's just for utility work.
    • Download AUTO.LST, convert Unix newlines (char 10) to the ATASCII newline (char 155 õ), and drop it in the HardDrive1 folder.
    • % LANG=C tr '\233' '\n' <AUTO.LST.TXT >AUTO.LST
    • Or you can just Media -> Edit an .ATR disk image, import file, and that has a newline conversion.
    • From BASIC, E."H1:AUTO.LST" <return> RUN <return>, pick Y. (Script AUTORUN.SYS), and enter:
      • ?"MAINMENU"
      • E."H1:AUTO.LST"
      • RUN
      • .
    • Change H1 to D1 if you saved it in your boot.atr.
    • Now it'll do that on every bootup from that floppy. Reboot to be sure it works.
    • If you make changes to your main menu, remember to LIST "H1:AUTO.LST". I use LIST/ENTER (text LST format) instead of SAVE/LOAD (tokenized BAS format) so I can read it from the Mac; BAS is slightly smaller and much faster to load/save, but it doesn't matter with emulation or an SD-card.

    • Atari-autorunsys

  • BASIC set up and tested, and it's a convenient place for little utilities, but now for real programming.

  • Atari Macro Assembler and Program Text Editor

    • Download this, read the fine manuals; more for MEDIT than the assembler unless you're really hardcore. I will probably do little or no assembly, even tho back in the '80s I could hand-assemble short programs directly into ATASCII codes to run from BASIC; bug-eating freak that I was.
    • Read the MEDIT manual. It's quite a respectable full-screen editor with command mode for search/replace, block editing, etc.
    • Open the Atari Macro Assembler and Program Text Editor.atx (ATX is write-protected or encrypted or something; you can't use them directly, and have to disable the SIO speedup hack in emulator) disk in drive 2 of your Atari (Cmd-2), Control -> Disable BASIC (which will reboot to DOS). So you want the program files off that:
      • DOS: C <return> D2:MEDIT,D1:MEDIT <return>
      • DOS: C <return> D2:MEDITCM.BAS,D1:MEDITCM.BAS <return>
      • DOS: C <return> D2:AMAC,D1:AMAC <return> (skip if you'll never write ASM)
      • DOS: C <return> D2:SYSTEXT,D1:SYSTEXT <return> (I think only needed for AMAC?)
      • Eject: Ctrl-Cmd-2
      • Reload your data disk, Cmd-1, disk2.atr.
    • Control -> Enable BASIC, LOAD "D1:MEDITCM.BAS" <return> RUN <return> and configure MEDIT however you like.
      • Language: PAS
      • Tabstops: Set at 5 and +4 after the existing ones, because 8-wide tabs are crazy in a 40-column screen. Yes, I'm a tabs not spaces guy, OBVIOUSLY.
      • Margins: 1,40
      • Colors: 12,4,14 (sadly can't be 0 or 2 background luminance, because the cursor is black)
      • Flags: Tabs: Expand, Shift-Lock: No (starts in lowercase).
      • Save & Return to DOS.
      • You can just copy the MEDITPAS.ECF to MEDITTXT.ECF, etc., you don't need to run the tool for each language, but it doesn't have a default mode. Note you also have to copy these to each disk you're editing on, or it switches back to the stupid defaults:
      • DOS: C <return> D1:*.ECF,D2: <return>
      • DOS: L <return> MEDIT <return>, filename D2:HELLO.PAS, and enter: 
        program hello;
var c: char;
begin
  writeln('Hello, Atari!');
  read(c);
end.
      • <option> exit <start> to save & exit. Note return doesn't execute commands in MEDIT, start does. Kids Today™ have some meme about how hard it is to exit vi? Ha ha, they have no idea. RTFM.

  • Finally ready to program in Action! or Pascal, which is what I mainly did back in the day.

    • Deep Blue C: Tragically underpowered version of Small-C. I loved it as an intro to C, but didn't use C for real until the Atari ST. It did produce standalone binaries and the compiler was easy to use, IIRC. 
      UNSUPPORTED FEATURES
  Features in C not supported in DEEP BLUE C are:
  1) structures, unions
  2) multidimension arrays
  3) Floating point numbers
  4) Functions returning anything but int
  5) Unary operators: sizeof
  6) Binary operators: typecasting
DIFFERENCES FROM STANDARD C
  THE DEEP BLUE C language has the  following nonstandard features:
  1. The last clause of a "switch" statement, either "case" or "default", must
be terminated with a "break", a "continue" or a "return" statement.
  2. The ancient =<op> construct has been removed. Use <op>= instead.
  3. Characters are unsigned. Chars range in value from 0 to 255.
  4. Strings can not be continued on the next logical line.
  5. C source code lines can be a maximum of 79 characters long.
  6. Functions can have a maximum of 126 arguments.
SPECIAL SYNTAX
  C uses several ASCII characters not available on the ATARI computer's
keyboard. In particular the braces have been replaced by to two-letter
combinations $( and $), and the tilde has been replaced by $-.  The $ character
is not used in C, so your editor's find and replace command can be used to
convert standard c programs into a format acceptable to DEEP BLUE C.
    • Action!: Custom language on cart for Atari, fantastic built-in editor (later the basis for the Paperclip word processor!), had a disk runtime system so you could distribute programs (also on AtariMania). But it came out a little later than my Pascal adventures, and it's a weird super-low-level language, and I think I'm in no mood to relearn it right now. Super goddamned fast, tho. May get into this if I'm frustrated later.

    • APX Pascal: Excessively complex process with a disk swap for every compile, compiles & links into PCode, no explanation of how to boot it. This is a very user-hostile compiler.
    • Kyan Pascal: Maze of command line tools. Doesn't work, at least for me, on emulation. It cycles through the tools, but never actually builds anything, eventually crashes and corrupts video. Makes a big deal of being usable from RAMDisk, but that doesn't matter on modern hardware.
    • Draper Pascal: Which I used in the '80s. Hilariously bad editor (but I can use MEDIT, so fuck that), compiler just fucking works, but only produces PCode (.PCD), so has to start from bootdisk or run Draper's menu then your program, ick. But this was no trouble to get running, so it wins.
      • Insert drpascal.atr in drive 1, reboot, boots into a menu.
      • 3 Compile program: D2:HELLO.PAS
      • 1 Run program: D2:HELLO
      • Total success! \o/ Hit any key to exit the program.
      • Drive 1, boot.atr, Drive 2, drpascal.atr, reboot
      • DOS: C <return> D2:AUTORUN.SYS,D1:PASCAL.COM <return>
      • DOS: C <return> D2:INIT.PCD,D1:INIT.PCD <return>
      • Cmd-2, disk2.atr
      • So now I can: DOS: L <return> PASCAL.COM <return>
      • And run Pascal programs. I could make a more focused runtime menu for it, maybe dir & list all the PCD files, the INIT.PAS source is included. If I ask it to compile, it prompts to insert drpascal.atr, and then I can switch back, which is reasonable.
      • Standard library is small but effective, seems like it has all the BASIC equivalent commands, and enough POKE/PEEK/ADDR stuff to let me do everything, including Player-Missile Graphics.
      • I can presumably now move all my source and disk2.atr contents to H1, so they can be managed & edited on the Mac, but I just wanted to get things running first.
      • Probably make another gitlab project (and actually sync it from git) when I get somewhere with that.

This took quite a lot of my hobby time doing something harder than actual work, to be honest. But I'm in a good place with it now.

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.