Defender is an arcade classic and one of the most successful titles of the era now known as the golden age of arcades. released in 1980, it was the first video game Eugene Jarvis co-designed, and he was one of a team of four coders who worked with pinball company Williams ( who wanted to enter the arcade market after the success of Space Invaders), and was one of a team of four coders who developed the game for the company.

We know that Defender was created by a pinball designer mainly because it was so fast and so difficult. Jarvis was a genius designer, but he was also accustomed to designing products in which the player's advanced skill and desire for mastery were taken for granted. His games never lost this quality, even if they softened somewhat over time: "Robotron 2084" was still maddeningly difficult, and "Narc" and "Smash TV" ate away at players' lives like nobody's business.

Anyway: the source code for Defender was posted on Github. This is the code for the "Red Label" version, one of four versions distributed to arcades, with interesting notes on assembly by Mr. Jarvis (or "Dr. J") himself.

Assemble defender

rasm phr2,defa2,defb2,amode0;-x (else cref symbol overflow)

rasm phr2,samexpa7

rasm phr2,defa2,. defb2

chain all to get diag. cf

load it all and hope it works

(note: note the order in which you load

note the selected block shit

dr j. 1/21/81

retired coder James Cuff was going through the code and found some interesting remnants of Williams' pinball legacy, including a ball timer and the number of balls played (no balls in Defender, of course).

Cuff also found an interesting annotation in what appears to be code for the game's "Attract" mode (a demo played by arcade machines to entice players). The first line is 'Time to blow up the enemy,' followed one line later by 'Blow up the bastard,' and before that, 'Move on to the man.' One element is 'for Eugene', before the machine 'makes it faster' and 'undoes it'.

I called Eugene Jarvis' current firm to see what he thought about the matter. His name may not be familiar to younger readers, but as he admits in an old interview with Gamasutra, "I'm always trying to replicate the success of 'Defender.' It's like I'm destined never to have that level of success again, and I keep dreaming about it."

He is probably a fan. He said, "I've always thought MAME was great in terms of preserving the legacy of the game. Graphics have advanced, gameplay has advanced, but it's fun to look at [older games] and play them and see the history of the business. It's a great history lesson and great entertainment in itself."