During a Macworld/iWorld keynote on Thursday, Ashton Kutcher and Josh Gad spoke about their roles as Steve Jobs and Steve Wozniak in the upcoming jOBS movie, and have responded to Wozniak's criticism of the film.

jOBS, a biopic depicting Apple's late co-founder Steve Jobs' life from 1971 to 2000, is scheduled for release in April, and premiered at the Sundance Film Festival on 27 January, where it was greeted by a mixed reception. Apple's other co-founder Steve Wozniak has publicly stated that the film is "totally wrong", after watching a minute-long clip of the movie.

"I adore Woz," said Josh Gad, who plays Wozniak in the film. "I really have a reference for him, having read his book iWoz, so I'll plug it for him; I know if he were here he'd plug it for himself. I really appreciate this man, and I hope that when he sees the movie in its entirety, he'll understand that we went to great lengths to capture the essence of his journey."

"It's hard to judge anything by a 20-second plus clip," Gad continued. "He commented that he would never wear that outfit; I'm sorry, I didn't know what his wardrobe was that particular week."

"It was an intensive journey for me and for Ashton," he added. "There will always be a debate about what we got right and got wrong. If I could sit down with him, I'd say it was done with the utmost love, admiration, and respect."

"We weren't there," added Kutcher. "In film making, you have to make a narrative that plays. If you look at the extent of the journey these two took together, there were a lot of moments where nobody else was there."

Discovering Apple

Gad revealed that he was a latecomer into switching from PC to Apple, but once he did "it completely changed my entire view of what technology could mean."

"As somebody who comes from a creative place, it was the perfect device for my needs, and I've been a hardcore Apple user ever since," he added.

Kutcher said that his first Apple computer was an Apple IIgs, which was released in September 1986 and then discontinued in 1992.

(Above: Left, Steve Jobs, right, Ashton Kutcher)

In preparation for the role of Woz, Gad said that he had to take programming classes, because he was "as computer illiterate as Wozniak was computer literate."

"Acting by its very nature if faking," he explained. "But if you don't really know what you're talking about, you can't sell it."

"Working with Ashton, who I kind of had a perception of prior as being a brilliant comedic actor, and then seeing his technical savvy was mind blowing," said Gad, referring to Kutcher's roles in American sitcom 'Two and a Half Men', as well as comedy movies such as 'Dude, Where's My Car?'.

According to Gad, Kutcher dismissed one of the props in the garage where they were filming (which was the actual garage in which Steve Jobs and Steve Wozniak began Apple), saying that it wouldn't have been out for another year.

Playing Steve Jobs

"For me," said Kutcher, "Steve Jobs as a person – I do a lot of angel investment… work with a lot of developers on building really amazing tools – so for me, he's an iconic hero, and someone who I try to emulate in my work. And someone who I learned an immense amount from."

Kutcher explained that he has never portrayed a character that isn't fictional before, so his role as Steve Jobs presented a new challenge for him as an actor. Kutcher found that playing Jobs was really scary because we have a daily reminder of him in our hands when we use our iPhones, iPads, Macs.

"Stage two was just overcoming the fear of playing someone that people know," Kutcher said. "I probably watched 100 hours of footage" of Jobs for research, he added, explaining that he also strung together audio files of everything Jobs said. "All you gotta do is start repeating Steve [Jobs] and you sound really smart."

Gad says he was equally terrified of playing the role of Steve Wozniak. He said that he first spoke with Kutcher over Skype (note: not Apple's FaceTime) to determine whether he should agree to take the role, because most of the scenes would be together.

"When we were shooting at the house we got to meet his step-mother and his sister, and so that was a pretty incredible experience," said Gad. "It was surreal for them to see this transpire all over again in the place where it happened."

Risks of Steve Jobs Fruitarian Diet

Kutcher also spoke about trying the Fruitarian Diet that Steve Jobs was known for adhering to. He said that it made him feel awful, and has previously revealed that he had to go to hospital afterwards. "That's why you should do what I do and eat everything but fruit," Gad chimed in.

There's a scene in the film during which Steve is working at Atari and gets a project assigned to him that he can't do himself. So he gets Woz to do the work, but lies to him about how much they'll get paid for the work. "I don't think Woz holds a grudge about it, so much as it just confuses him," said Gad. "Here's a guy he touches with his greatest resource, his mind, and it was strange betrayal that he didn't know quite how to deal with."

Kutcher said: "The way I saw it was, I got a job to redesign this game, and for every circuit that we eliminated from the process we actually got a bonus, and I knew a guy who could do it, and so I hired him for X amount of money to actually perform that job. That's how I justified it as a character, which was to my assumption would be, Steve was employed at this place and gets this job and hires Woz and pays him to do it, and keep profit for himself. He was looking for a margin and he found one."

When asked about his knowledge of Apple, Gad said: "I was born in 1981; my knowledge of the first phase of Apple was very limited. What I knew was what my generation kind of grew up with: The iPod/Pixar/iPhone version of the Apple legacy. Here we were telling this story that I didn't really know. The second I delved into the research – I read iWoz, and the Isaacson book – it was sort of like Lennon/McCartney, this one in a lifetime duo."

"This idea that this kind of entrepreneurial mind who had this training and this background in all different things, including spirituality with his time in India, the idea that these two would meet and it would be this perfect storm fascinated me," Gad continued. "Because there are very few stories of that kind of massive success. To me, that was the most interesting part of that."

"I am in awe of what Steve Wozniak created and did," said Gad. "And his legacy. But, I'm also in awe of the other side of him, that isn't really talked about, which is this prankster, fun-loving spirit. This energy, you tend to think of these types of people as very intense people. The fun-loving nature that he brought to his work, is the thing I think in my own business endeavors that I really love."

Kutcher believes that Job's passion to paying attention to the needs of the consumer to "the most microscopic detail" came from a true care about the user experience.

"When I heard him say this in an interview, he was talking to me," said Kutcher, describing Jobs' lesson as "Don't settle for what life gives you. Make it better and build something."

The last question of the keynote for Kutcher was: "If you had your investment firm and Steve Jobs walked in barefoot and a little less than perfect smelling and pitched you on his technology, would you have written him a check?"

To which Gad said "We're at Macworld, say yes!", and after some hesitation, Kutcher replied: "I'll say this, when I look for companies to invest in, I look for people that are hacking a solution to a problem, where there's a great density of people hacking that problem's solution."

"I would hope that I would have invested? And I can say that there are some hardware companies today, like Smart Things building intelligent objects with open software that you can actually develop tools with, and I invest in that company... So I hope I would have been intelligent, wise, and intuitive enough to see the possibility," Kutcher concluded.