Back in April, my editor at Amazon Kindle Singles commissioned me to write an oral history of Late Night with David Letterman. Since, I spoke with somewhere between 40 to 50 people who worked or appeared on the 12:30 a.m. NBC talk show — the one that transformed comedy forever with its ironic obsessions and enabled a generation of writers to flourish, from Jimmy Kimmel to Judd Apatow to Jon Stewart. But many are likely unaware of Letterman being some kind of comedy god; the master tapes of his years at NBC have been locked in a vault since he changed networks in 1993. “To those people [who haven’t seen the original Late Night], Dave is like this old guy on TV,” Jay Mohr explained on his podcast in 2012. “Dave was Chappelle’s Show. It was that underground and that young and that cool.”

Mohr isn’t the only one who can attest. In AND NOW…An Oral History of “Late Night with David Letterman,” 1982-1993 — available for download to your Kindle app for the low, low price of $2.99 — one of my interview subjects is actor Mark Hamill, a recurring Late Night guest in the early years who is easily in the running as one of its all-time #1 fans. In August, Hamill and I had a hour-long phone call in which he shared his questionably unhealthy Letterman obsession — keeping a journal, recording episodes for decades — and how he became something of a de facto archivist for the show. The majority of Hamill’s interview didn’t make it into the e-book, but I felt it deserved a place somewhere for posterity, i.e. for other fanatics to document in their Letterman journals. They’re out there. Believe me.

Here’s an abbreviated version of that call.

BRIAN ABRAMS: Rolling Stone’s David Browne wrote in 2011 about your keeping a journal [of Late Night] when you lived on the Upper West Side and how in love you were with the “Viewer Mail” segments.

MARK HAMILL: It wasn’t specifically “Viewer Mail,” but that gets into it. First of all, I love comedians. I’m fascinated with the form. It seems to be one of the more bold and brave things to do in show business where you have no one to blame but yourself if you’re not successful. You can always blame an author, a playwright, a director — it’s never your fault. With comedians, they’re just “out there.” When I saw Letterman, I liked him from the beginning. He had a sense of irony and attitude that reminded me of other comedians I liked a lot. He seemed to, like Johnny Carson, have this secret weapon of not being able to bomb because he would make flatter moments funny by commenting on them. Other comedians do that too, but something about Letterman I thought was just gold.

BA: When did you first catch Letterman?

MH: When I saw his [short-lived 1980 NBC] morning show, I said, “This is the next wave of comedy.” It harkened back to Steve Allen, who I loved as a kid, who would go out into the street and do observational humor that was so clever. And I thought, “This is really odd” because this show is so wrong for morning TV, but I can’t get enough of it. And of course it was cancelled. I was really depressed. I have this feeling that things that I love too much are destined to be cancelled. I don’t get over it very easily. I’m still mourning the loss of Square Pegs and Dabney Coleman in Buffalo Bill. Recently I was upset that they cancelled The Neighbors on ABC. Sometimes I have a feeling that, if I love it, it’s the kiss of death. Somehow I’m responsible.

BA: So you definitely caught Letterman’s morning show.

MH: His audience was stay-at-home housewives and so forth — people that would watch game shows or soap operas, which was so wrong [for him]. They did a lot of things that would later carry onto that Late Night show, but I was depressed [when it got cancelled]. I think I read an anecdote at the time, that Letterman himself was sort of in a funk after the show was cancelled and went to see The Empire Strikes Back. And, of course, at the end we all got our butts kicked by the bad guys and it ended on a really down note, and he said that cheered him up. I never asked him about it personally, so I don’t know if it’s true. I don’t know if the exact timeline is right for that story.

BA: He started the morning show in June [1980], and it was cancelled in October.

MH: Oh, well [ESB] was still in theaters in October. So it could have happened. When the announcement was made he was doing his new show called Late Night, I remember it started in February of ’82. I was just absolutely a fan from the get-go. The reason where I got to the point where I was keeping shows and was keeping a journal was that I was going away to make Return of the Jedi. And I had somebody housesit in my house in Malibu. And I bought a huge box with a couple of cases of videotapes.

BA: So this must have been spring/summer of ’82?

MH: Yeah, I had an apartment in Manhattan, and [told my house-sitter], “Look, we’re going to be gone for a few months — three or four months, I don’t know how long it’s gonna take — but there’s a show I want you to tape because the odds are, by the time I get back, it’ll be cancelled. And so tape every show.” When I came back, there was this huge backlog of shows. So I would start watching them at my leisure, and one of the things that struck me was that there were elements of shows that I couldn’t conceive of taping over them. I said, “Oh, I’ve gotta keep this.” So I got that setup where you have two VCRs, and you could transfer from one [VHS recording] to another. And I went through and took out mostly his bits where he went out into the streets — the so-called “found humor,” the misspellings of restaurants or whatever it was. When I got back, I started a compilation tape of all of his best bits, including “Viewer Mail.”

BA: I believe June of ’83 was when you first guested.

MH: You don’t meet Dave until you really go out [on the set]. I think I saw him in the makeup chair, and I asked him “Where in the world did you find Larry ‘Bud’ Melman?” I wasn’t really speaking to Dave. I was sitting next to him, and I was kind of talking to the makeup artist. When I asked that question, he said, “We suspect inbreeding.” Which was funny, but he’s not someone who comes into your dressing room to say, “Welcome to the show.” He’s very much to himself, which is fine with me. I sometimes don’t like meeting people that … I like the people that I watch to be, you know, the people that I watch. Sometimes you meet people, and they’re disappointing or they’re not what you think they are or they give you a dimension that alters your perception of them when you watch them as performers. But be that as it may, I started a little sort of catalog so I wasn’t repeating stuff that I had taped. And it becomes almost like an addiction. You can’t stop. Once I started, I said, “When am I going to stop this? It’s just crazy.” It was kinda fun. I put Letterman on the timer. Sometimes I’d watch it live and mentally note, “Oh, I’m gonna keep that. I’m gonna keep that.” But also, too, if you put it on the timer, you get a backlog and you can watch most of ’em over the weekend. Or you can watch ’em the next morning when you and the wife are making breakfast or whatever.