The Coolest Thing In The World Is CP/M For 6502

Is that hyperbolic? It probably is. But the heart wants what it wants, and what mine wants is CP/M for the MOS 6502 processor. Set Side B is a blog about computer entertainment, in all its many forms, and this qualifies in my mind, because it’s not like anyone’s going to be using it do real work. Right?

I found out about it through the (mostly) wonderful blog The Oasis BBS. It’s called CP/M 65, and it was made possible when CP/M’s source was opened in 2022. Wait, maybe I should explain what CP/M is. Sure, it has a Wikipedia page, but I like explaining it.

Output of the DIR command on the C64 with the system disk in the drive.

Gary Kildall created CP/M, “Control Program for Microcomputers,” for the Z80 microprocessor, and it became the first widely-used standard OS for home computing. Its importance and influence cannot possibly be overstated: PC-DOS (later known as MS-DOS) was created as a clone of CP/M for the 8086 processor, meaning, the reason .COM files are still technically considered executables, and why we still have drive letters in Windows 11, are both directly because of CP/M.

A case could be made that, if IBM hadn’t made the IBM PC out of standard parts, making possible the huge market for clone machines, it’d still be a CP/M world today, in some way. It was the first standard OS, one where it ran on machines made by more than one manufacturer. Many of the CP/M machines companies, the Kaypros and Osbournes, are gone now, but they had quite a large niche at one time.

Conway’s Game of Life, for CP/M 65. Because it’s not really a computer until someone’s run Life on it.

Commodore released a CP/M cartridge for the Commdore 64, an amazingly ridiculous and rare package because the C64 used a 6502 processor. The cartridge worked only because it contained a Z80 processor inside itself, and put the 6502 in the system to sleep to do work. It ran much more slowly than other CP/M systems, and on top of that it still had to use Commodore’s 1541 disk drive, a fatal flaw, because it meant that while it could run CP/M software, it couldn’t read the disks that had them, because CP/M’s native disk format couldn’t be read by the 1541’s read heads. (The C128 had a built-in Z80, and the 1571 disk drive that was made for it could read CP/M disks natively, but by that time CP/M was already dying, pushed out by the PC standard and all those clones I mentioned.)

This thing I’m posting about, CP/M 65, has no relationship to that woeful product. It’s a port of CP/M to the 6502 processor. It can’t run Z80 CP/M software. But in all other senses, it is CP/M. What that means is that it has its own BIOS.

CP/M’s BIOS is what allowed its software to run machines made by different manufacturers. The BIOS acted as a translation layer between the hardware and the software. Programs wouldn’t interact with the hardware directly, but instead make calls through the BIOS whenever they needed to use some part of the hardware, like when it needed to access the disk or output characters to the screen. The result was that unless the software was written specifically to take advantage of a computer’s specialized hardware anything extra it had would go unused, but it also meant that a software developer could write one program and, so long as it restricted itself to interacting with the system through that BIOS, it could run on any CP/M machine that could read the disk.

DIR is the built-in CP/M command to report disk contents, but this release contains LS for those with that muscle memory.

CP/M 65 provides such a BIOS for all of its supported platforms, and as a result, while using it will give you a plane-jane, character-mode program, it’ll let you write a program that will run on any of them. Indeed, since this version of CP/M supports relocating executables, its programs can run on a much wider variety of hardware than original CP/M could. You can write a single program that can run on a Commodore 64, VIC-20, BBC Micro, Atari 8-bit, Apple II, KIM-1(!) and, if you can find the incredibly obscure keyboard and disk drive hardware for it or else emulate them, the Super Nintendo Entertainment System(!!).

But on a C64 it shines slightly more than the others, because it has integrated fastload routines, meaning that it gets around the C64’s greatest flaw, its horribly slow disk drive.

So this basically means now 6502s have their own cross-platform version of DOS, or something a lot like it. It has little software, but it does have an assembler, and a version of BASIC, and if you don’t mind writing it on a (pah!) modern computer, you can also write programs for it in other languages.

Behold the PETSCII Mandelbrot set!

If you want to try this wonderfully misbegotten thing, something like Frankenstein’s Monster wearing a ribbon, its GitHub is here, and you can find binary release disk images here. The one with the extension .d64 is the C64 version, and it loads right up in the Commodore computer emulator VICE, although I found out it’ll fail to boot unless you turn on “True Disk Emulation” for Drive 8. But it works! It comes with an assembler and BASIC, and a vi-like text editor, an implementation of Conway’s Life, and even a Mandelbrot set plotter. I kind of want to write software for it!

CORRECTION: Silly me, here I was assuming that CP/M 65 itself was a fairly recent thing, but as it turns out it’s been around for around 30 years!

CORRECTION FOR THE CORRECTION: Well the guy working in this very long Youtube playlist (maybe 31 hours?) created it in 2022, which isn’t 30 years ago. Ah well!

Indie Showcase For 6/20/25

Each week, the indie showcases highlight the many games we play on the stream here (at Game Wisdom). All games shown are either demos, press keys, or from my (Josh Bycer’s) own collection.

00:00 Intro
00:14 Tunnet
02:07 Schim
03:19 Astor Blade of the Monolith
05:03 Flathead
6:25 Tower of Mask
8:01 Devilated

Where Do Mario Kart World NPCs Go?

Mario Kart World upends the series in several ways (not the least of which in price), but the biggest change is that the game now takes place in an open world, one that you can roam around freely, and even the main tracks in the Grand Prix are supplemented by races that travel between them.

One consequence of the game world is that the NPCs that inhabit it have a bit more of a life than in past games. In N64 Toad’s Turnpike, they’re just boxes that travel around the loop getting in the racers’ way. But now, when you’re exploring in Free Roam, you can pick out a specific driver and follow them around.

And what do you know, there actually seems to be a bit of an inner life going on there! They don’t seem to pathfind between locations, sadly, but they can get the mad yen to drive off the road and tear across the desert. And, surprisingly, a drive can get out of their car, which is more than the player racers in the game can do!

OnADock, on Youtube, made a 14 minute video where he followed a Toad around on their travels through the Mario Kart World, um, world. Maybe it’ll inspire you to do some investigation of your own?

Loadstar Finds: Zorphon

Loadstar was a disk magazine for the Commodore 64 that lasted for 22 years! I’ve been put in charge of organizing its archives. From time to time I’ll present something interesting from its thousands of published items.

Even though I’ve been spending a lot of time working on the Loadstar project, I’m trying not to overwhelm this blog with items related to this Commodore 64 disk magazine. So for the time being I’m restricting myself to weekly Loadstar posts at most. Maybe on Wednesday? How would “Loadstar Lendsday” be as a name? Hm, not great. I’ll work on it.

This week I bring you one of the most polished games Loadstar published, Zorphon by Nick Peck, from issue 39. Here’s some demonstration video I recorded and posted to Youtube (13 minutes):

While he did have a few miscellaneous other items published on its disks, Nick Peck only ever made two games for Loadstar. Both are great, technically impressive, programmed entirely in machine code, and challenging. (The other is Paragon, from Issue 50.)

Zorphon is a space shooter in the vein of Gorf, where each stage offers different gameplay. Zorphon has three stages that loop, although there is an extra one, “Genesis,” that plays before the first loop, that’s only encountered at the beginning of the game.

You have your standard-issue spaceship that’s locked to the bottom of the screen, that can only move left and right, like the ships in Space Invaders, Galaxian and Galaga. This poses special problems in the stage that plays like Centipede: if one of the purple space bugs makes it down to your ship’s level it’s done for, because it’s not possible then to shoot or dodge it at that point, so it’s essential to ensure that doesn’t happen.

I played this game long ago, when it had just appeared in the magazine’s September 1987 issue, and even though it’s a fairly simple game, its quality has stayed with me all these years. There are different ways to represent moving objects on the Commodore 64. The most obvious, and smoothest, way is using its hardware sprites, but there are only eight of them. You could use sprite multiplexing to reuse them as the raster beam traces down the screen, but that poses certain limitations on the graphics and gameplay.

Zorphon instead chooses a different means of representing enemies, it draws them on the character map. That means that the attacking aliens can only be displayed on character grid boundaries, which is a drawback, but it takes the cap off of the number of foes the C64’s VIC-II chip can display. You also get free collision detection: just check the register at memory location $D01E (53278) to see if the sprite that represents the player’s ship comes in contact with any background graphics data. This method means the collision detection is pixel perfect, the flag isn’t set if the sprite overlaps empty portions of a character cell. This isn’t always desirable, but the ship in Zorphon is large and chunky, so mis-detected collisions are unlikely.

Zorphon is, of course, in the archive of Loadstar Compleat that I maintain, although admittedly it is $15 there. You could also play it on the Internet Archive’s emulation of it. That is a “cracked” version though, which I find funny because Loadstar is for the most part not copy-protected. It will offer you unlimited lives, which is also funny since it’s a score attack game, and running out of lives is the only way for it to end. I think Loadstar #39 is also available there somewhere, but I can’t seem to find it easily.

If you decide to try it, by however means, here’s some tips.

All the stages of Zorphon are made more challenging by your ship’s limited firepower, having only one shot onscreen at a time. If you miss your shot you’ll have to wait until the other one exits the screen to try again, and that can take two or three whole seconds. Getting into a rhythm of shooting at monsters helps a lot, especially in the first stage, which is all about finding that rhythm.

The bouncing enemies phase of the first level, Genesis. Until you figure out how to clear all of them, you’ll be stuck cycling between Genesis’ two phases.

The first stage, Genesis, has two phases. The first end when you shoot enough of the red TIE-Fighter enemies, but to finish the second you must destroy all of the blue bouncing aliens within a limited number of passes. If you don’t get all of them in time, they’ll completely replenish, and if you fail at it again you’ll be sent back to the TIE-fighter phase!

The blue bouncing enemies are really hard to hit. I find it’s best to hang out at the left side of the screen and shoot the ones there. Every time they pass by, they distribute themselves again, and there will always be an enemy on the left side unless there’s only one left (which will move to the center of the screen).

Since Genesis cycles until you pass it, one way to get a good score is to purposely repeat it, letting the blue enemies reset and then fighting the TIE-fighter phase again. Once you know the patterns Genesis isn’t very hard, and can be easily farmed for points. It’s not a very exciting way to play though.

The Challenge stage, which is pretty hard!

The second stage, Challenge, will be the end for many players. It’s the Centipede-like stage, but your shots do nothing to the mushrooms! Many of the enemies wipe out mushrooms when they pass over them, which will help you out a lot.

To finish Challenge, you must wipe out two complete waves of centipede aliens, and a few pairs of segments that come in between them. After the second wave spawns, clear the stage of centipede segments and you’ll progress.

The third stage, Attack, is even harder!

The third stage, Attack, is really tough, and made harder by the fact that it’s so hard to get to it that you can’t practice it easily! Maybe getting better at it is a use for that infinite lives cheat on the Internet Archive version? Maybe! To finish it, I think you have to shoot enough of the bouncing asterisk enemies to pass it. Look out for the exploding bombs dropped by the flying saucers that come in from the side!

I don’t know remember if I’ve ever finished Attack and gotten to the last stage, but I seem to remember seeing a full loop at some point so I think I have. See if you can do it.

Indie Showcase for 6/16/25

The weekly indie showcases highlight the many games we play here on the channel (Game Wisdom). Games shown are either press keys, demo builds, or from my (Josh Bycer’s) collection.

00:00 Intro
00:14 Path of Achra
01:32 When the Light Dies
3:34 Moonglow Bay
4:49 Hemlock
6:04 Baladins
7:54 The Tower on the Borderland

Sundry Sunday: There’s Something About Pokemon Mystery Dungeon

Sundry Sunday is our weekly feature of fun gaming culture finds and videos, from across the years and even decades.

From TerminalMontage, who’s shown up here multiple times before. I thought maybe I might have already posted this, but a quick search seems to indicate that I haven’t, and it’s a useful intersection between Nintendo things, roguelike things, and silly things.

Specifically, this Something (5½ minutes) is About the original releases of Pokemon Mystery Dungeon Rescue Team, Red and Blue. And you’ll probably best see what all the About is about if you’ve played the original.

I’ll throw in some notes about the references in this video:

  • The rescue mechanic, which involves teleporting rescued Pokemon. How the hell does it work?
  • Kecleons, the shopkeepers in PMD, are as scary as depicted here. To think that this would be a lasting legacy of the Nethack Devteam’s Izchak Miller.
  • The music in the volcano segment is from the game, and it does the thing that the kids these days call “slaps.”
  • Make sure to fast forward through the credits for a final closing gag, where we find out who Cyndaquil really is.

The 8 Bit Guy’s Histories of Commodore

I’m still deep in the 8-bit computing weeds right now, and I always look to connect what I’m personally researching with what I put up on Set Side B. So lucky you, what I’ve been looking at today is The 8-Bit Guy’s videos about the history of Commodore!

It’s a series of videos (yes, on Youtube) exploring the history of that company, both lauded and hated. They released one of the best-selling computers of all time in the Commodore 64, but founder Jack Tramiel wasn’t all that great a guy. Word is the C64 was priced so low because he held a grudge against Texas Instruments, a calculator company Commodore competed against, so he moved to undercut and destroy their sales of the TI-99/4A, turning it into just another computing history footnote. He also bought rising star MOS Technologies, which had a terrific things going with the ultra low-cost 6502 processor, but then basically only used the company as Commodore’s bespoke chip fab.

But say what you will about Tramiel and other strong personality company Presidents and CEOs, when they’re successful, their ups and downs make for interesting times, to read about and hear. So “hear” you go!

The series is collected into a 13 video playlist, 8 parts of the series itself averaging about 25 minutes each, plus some extras. It’s a tale that begins with one of the first (if not the first) pre-assembled mass market personal computers, and ends with the Amiga. If the dice had only rolled differently (and maybe if Tramiel hadn’t bee forced out of the company), then instead of Apple rising to become the leading computing device maker in the world, we might be using Commodore C-Phones today.

An Overview of Type-In Computer Magazines

In the old old old old old old old OLD* days, people wrote computer programs by either filling boxes on paper cards or punching out squares, like they did (maybe still do?) for standardized tests. The cards would be fed into card reading devices, some of them called Hollerith machines, to be read into the computer’s memory. (Asides: Hollerith machines were invented in the 1800s. IBM’s start was in making them. IBM’s website though won’t be keen to publicize that they were used by the Nazis.)

(Another aside: What do the olds mean? Old #1: before social media. Old #2: before smartphones. Old #3: before Google. Old #4: before before the World Wide Web. Old #5: before the internet. Old #6: before online services. Old #7: before home computers. Old #8, the all-caps one: before timeshares. There is an awful lot history in the early years of personal computing that gets overlooked.)

The ultimate point after all this discursion is that paper, while little used today, is a time-honored way of entering computer programs. A while after that neolithic era, when home computers first hit it big, there grew a market for programs that weren’t as big and expensive as boxed copies on store shelves. That was the age of the type-in program magazine.

It’s the same age that that Loadstar thing I keep bringing up belongs to, but truthfully it lies only on its edges, as it was a disk magazine, created specifically to bypass the trial by fire that type-in magazines subjected its users to: sitting at a keyboard for hours, laboriously entering lines of code, or even plain numbers, in order to run some simple game, novelty, or other software. Loadstar itself served as the disk supplement, that is, media that carries all the programs from a print magazine’s issue, for both Commodore Magazine and Power/Play. (That age of Loadstar stretches from issue 9 to 61.)

I don’t know when the first magazine that published software in print form was, that’s a solid fact kind of question, there definitely was a first at some point, but there’s been tens of thousands of magazines, some of them really short-lived and obscure, and there’s a great many edge cases to look out for. Mad Magazine, to offer just one example, published a type-in in one issue.

To state that solid fact definitively requires more time and resource access than I have. But a strong claim could be made for The PET Gazette.

Computer magazines used to look like this! That’s what they’ve stolen from you!

The PET Gazette’s first issue was near the end of 1979. It was more of a fanzine, with a few aspects of a science journal, than a general magazine. It served a highly motivated and focused audience, the kind who would drop $800 in 1970s money on a machine that had 4 or 8K of RAM. The kind who thought making a machine perform automated calculation or data manipulation, all by itself, seemed really really neat. (I kind of feel that way, even now.) The kind like that, or that else bought one of the even earlier kit computers, like the KIM-1, which users had to assemble from parts, soldiering iron in hand, and for which a video monitor was a hopeless extravagance.

I would say at this point that you might know PET Gazette by its rebranding in the early 80s, to COMPUTE!, title in all caps, with exclamation point. But then I would be expecting you to say “Wow, I had no idea!” But who these days even remembers Compute? (I’m not going to persist in replicating 45-year-old marketing stylization, I have difficulty making myself type Xbox.)

As its title indicates, PET Gazette focused primarily on the PETs, along with the KIM-1 which is like a sibling. Compute served a community of users of many different platforms, of like half a dozen: Commodore microcomputers of course, but also Atari 8-bits, the Apple line, the TRS-80s, the early days of the IBM PC, and at times even some more esoteric models.

Compute’s first issue. At the start, it used a period in its title instead of a bang.
Compute’s last issue. It had dropped type-ins a few years before. By this time it had dropped the exclamation point and was owned by the publishers of Omni (hence the font of its title). It got sold to the murderers of many a tech magazine, Ziff-Davis, in order to get ahold of its subscriber list.

Compute soon spun off two or three subscriptions for specific platforms, for users who wanted more than what was limited, by space reasons, to one or two programs an issue. By far the most significant of these was Compute’s Gazette, its title a tribute, to those who knows, to the Compute empire’s origins.

I’ve mentioned here before, certainly, that Loadstar lasted for a surprising and amazing length of time, 22 years. Compute’s Gazette (Internet Archive) wasn’t nearly so long-lived, but it still made it pretty far. Wikipedia claims that it survived to 1995, but really its last issue as its own magazine was in 1990; then it persisted for a bit as an insert in Compute, then as a disk-only periodical.

Look at that cover! Distinctive! Informative! Interesting!
…and the last cover. I don’t think it’s nearly as interesting, but by that point it was lucky to be a magazine at all.

Fender Tucker tells me that when Compute’s Gazette closed up, they paid Loadstar to fulfill their remaining subscription obligations, so at least they did right by their remaining customers. It was a dark day when CG perished, though, the former heavyweight of the type-in scene.

Some other type-in magazines of the time were Ahoy! (again, with an exclamation point):

Ahoy also had a distinctive design!

…and Run:

The word has arrived via the Floppy Days podcast that the Compute’s Gazette may soon return. What really happened is that James Nagle saw that the trademark had lapsed and registered it himself. There’s no continuity of editor, writer or IP with the original. Yet I still hope that Nagle’s effort, which rebrands the Gazette as supporting all retro computing platforms, succeeds. His heart is in the right place at least. Here’s their website. I hope that they at least have the sense to offer a way to enter programs other than typing them in by hand; that was always the worst thing about these magazines.

Oddities with Smash Melee’s Home Run Contest

Smash Melee has had a huge amount of attention payed to it over the years, and one source of player obsession has been the Home Run Contest.

In brief: Smash Bros. games are about racking up damage to a target, measured in percent. The higher the percent, the further an attack target flies when struck. The idea of the Home Run Contest is to do as much damage to a special Sandbag character, which doesn’t move on its own, in 10 seconds, then to hit it as hard as you can, usually with a baseball bat item, to make it fly as far as possible.

The Home Run Contest has been in every Smash Bros. game since Melee, and its first implementation has lots of weird things about it. Like, if you set the game language to Japanese, you get a slightly smaller platform, which makes your distances count slightly longer.

Lots of oddities are pointed out by Youtuber “Practical TAS”, in their 26-minutes video, here. Warning: serious geekery ahead!