When John Carmack talks publicly these days, he's usually focused on intricate technical matters, the blue-sky potential of virtual reality, or occasionally business-focused lawsuits. So when the Doom co-creator and Oculus CTO used a lengthy Facebook post to open up about his memories of Apple's late CEO Steve Jobs, it provided an interesting and rare look into two enigmatic tech luminaries.

Carmack leads off by recalling his fondness for Jobs' expensive NeXT workstations, mentioning a failed marketing deal to feature "Developed on NeXT" branding on the original Doom, well before it was a cultural phenomenon. That failed marketing deal put Jobs and Carmack in each others' orbit, a proximity which Carmack says he used to convince Jobs to adopt OpenGL 3D graphics standards on Macintosh, rather than using Apple's own proprietary API.

Despite the problems with Apple's OpenGL support (many of which the newer Vulkan standard seeks to fix), Carmack says getting Apple to adopt the open graphics standard ended up being key to getting mobile phone companies to adopt it years later, preventing a situation where "half a dozen SoC vendors [roll] their own API back at the dawn of the mobile age." He considers that knock-on effect "one of the biggest indirect impacts on the industry that I have had."

Carmack also recalls his disappointment with Apple's initial focus on "Web Apps" for the original iPhone and how he argued hard for the "real native access" that would eventually be embodied by the iOS App Store and its developer SDK. He says he pushed back against Jobs' security-based excuses for initially limiting developers' direct access to the iPhone, leading to a "vigorous conversation" that made other Apple employees back away from an angered Jobs.

Later, in a 2008 interview, Carmack infamously said that "Steve Jobs doesn't care about games," a statement he predicted would "get fed back to [Jobs] and I'm on his shithead list for a while on that, until he needs me to do something else there." On Facebook, Carmack confirmed that public comments like those put him on Jobs' "down side," leading to secondhand reports that Jobs "explicitly instructed them to not give me access to the early iPhone SDK when it finally was ready."

"It was often frustrating, because he could talk, with complete confidence, about things he was just plain wrong about," Carmack said. "But when I knew what I was talking about, I would stand my ground against anyone."

Carmack's full post includes plenty more personal reminiscence about Jobs requesting Carmack to delay his own wedding to attend an Apple keynote, Carmack's difficulty showing a blood-soaked Doom 3 at a subsequent Apple event, and much more. "The Steve Jobs 'hero/shithead' rollercoaster was real," he recalls. "I corroborate many of the negative character traits that he was infamous for, but elements of the path that led to where I am today were contingent on the dents he left in the universe. I showed up for him."