In 2022, I published Nosh Kosh — a Jewish spin on Pac-Man for the Apple II — as part of the Kirschen software collection that I rescued from cartoonist Yaakov Kirschen’s floppy disks.

Since then, I have played “Nosh Kosh” on and off, but inexplicably I have never been able to get past the first level.

Last week, I decided it was way past time to beat it.

I wanted to know if the later levels had different designs. I also wondered if the game might have an ending like “Borders” — one of the other Gesher games in the collection — or if the level designs would just keep cycling forever, similar to Pac-Man, Donkey Kong, and other classic arcade games of the time.

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A kosher Pac-Man

First, let’s recap how to play. Like Pac-Man, “Nosh Kosh” is all about eating. But this is an educational action game, meant to teach kids about kashrut — Jewish dietary law.

The skullcap-wearing main character, Chunky, must race across the screen gobbling up carrots, hamburgers (meat), and ice cream cones (dairy). Carrots are safe to eat any time, but you have to be careful with the meat and dairy. If you eat a hamburger, then six “hours” will be added to your timer. If you eat an ice cream before the timer has run out, Chunky will shout “oy” and die. And, just as Pac-Man is chased by ghosts, Chunky must dodge three non-kosher enemies: Freddy Frogslegs, Peter Pig, and Larry Lobster. If any of them touches Chunky, he’ll die.

Beating Level 1

So, last week, I sat down and started playing. Slowly I developed some strategies. I kept playing and kept improving, until finally I managed to eat all the food on the screen. I had done it — I finished Level 1!

I watched as the skullcap-wearing main character, Chunky, raced across and down the now-empty screen, presumably on his way to Level 2 … then, suddenly, the game crashed with an error.

The text of the error appeared to say “illegal quantity error,” but many of the letters were replaced by sprites.

I tried again, but every time I beat Level 1, the game would error out.

Two versions

The bug was so frustrating! But I also worried — I had received three floppy disks from Kirschen with copies of Nosh Kosh years ago. Did they all share this bug?

In 2022, I had determined that among those three disks, there were two versions of the game. Version “A” was on two of them, and “B” was on one.

Then, last year, at the Breman Museum in Atlanta, I imaged a floppy disk with demos of both Nosh Kosh and Borders. Gesher had sent these demos to the Atlanta Jewish Federation, which had contracted with them to produce Jewish games with Georgia-related content.

This week, I decided to calculate checksums for all four disk images and compare them again.

It turned out that Version “A” was the one with the bug. Two of the Kirschen disks as well as the Breman disk are Version “A”.

The other Kirschen disk is Version “B.” I played it several times, and it seemed not to have the bug. Using this apparently cleaner version, I was finally able to get to Level 2!

Level design

As the food sprites began to populate across the screen, I could tell that layout was slightly different. But because the game screen is so noisy with wall-to-wall sprites, it was hard to perceive visually what exactly had changed.

I kept playing, and as of this writing, I’ve been able to reach as far as Level 7. I learned there are only five level designs, each one harder than the one before.

By taking screenshots and diffing them, I figured out what precisely was changing from level to level. Basically the Gesher programmers increase the difficulty by replacing some of the “safe” carrots with the tricker ice cream or hamburgers.

I feel pretty certain now that “Nosh Kosh” does not have an ending. If you reach Level 6, then the game just cycles back to the first (and easiest) level design.

Want to play? You can find Version “A” of “Nosh Kosh” on the Internet Archive.

Want to learn about the history of this game and several others like it? Check out my talk “Saving the software curiosities of Ya’akov Kirschen”, presented to the Atlanta Historical Computing Society last August.

Postscript

Finally, a weird postscript:

One full week after I started this odyssey, I decided to write up this blog post. In preparation, I wanted to capture a video of the bug in action, so I began playing Version “A” again. But this time, the bug never recurred. I was able to beat Level 1 on Version “A” several times and advance to higher levels.

So what’s going on? I’m not sure yet. Was it just weirdness in the emulator? Or is the bug only triggered by a weirdly specific condition that I never repeated tonight?

I don’t know.

I guess I’ll have to keep playing.