Episode: 681
Title: HPR0681: My first computer
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr0681/hpr0681.mp3
Transcribed: 2025-10-08 00:47:45

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music
This is Mr. Gadgets here in Kansas City, and I've been wanting to contribute to Hacker
Public Radio and when I found or heard on a promotion that you had a phone in line, this
seemed perfect to me because, hey, that's what I do, I sewed it in. You may have heard
me calling in to various podcasts. I never have really started my own podcast, at least
not on a regular basis, hoping to do that in the future. So I thought I would contribute
my first computer. Now, I'm a bit older than you, average, I think, because I'm on the
north side of half century, and I have been doing things with microcomputer since really
pretty much the very beginning. So my first computer I actually owned and was able to
program, even pre-dated microcomputers, I suppose, because I believe it was in eighth grade
advanced math class. We spent some time learning about the, you know, at least the principles
of program. And I had a cardboard kind of a mechanism that had little sliders up and down,
and you could actually write a program, and then you would run through and do things with the
accumulator, and the memory slots, and all this kind of stuff, and you could run your program,
and see if your program logically worked the way you thought, and you got the result that you
thought you would get. So that, I guess, technically, was my first computer, but as far as my actual
first microcomputer that I ever owned, I didn't have the money. It was during college that the,
the initial MITF, you know, computer, may start at the revolution by being on the cover of
an electronics magazine, and all that kind of stuff. The legendary, you know, Paul Allen comes to
fill gates over at Harvard, and says they're starting revolution without us, and they decide to go
down and, you know, write a basic compiler, and all those kinds of things, and Microsoft get started.
And the first single board computer that I could afford to purchase and build was a Cosmac
Elf, which was an 1802 processor. It was from RCA, and you've had some advantages over some of
the other processors of the day. This is back in the days of the, you know, we aren't talking about
the 8088. We were still talking about the 2004 and the 2008, you know, processors here, and the
Cosmac Elf 1802 had an advantage in that it was CMOS, so it was low power, and it multiplexed some of
its processor lines, because it was still a 40-pin DIP back then, and there were only so many things
you could do with the 40 pins, and most of the other microprocessor chips, even the 2004, and especially
the 8th of all kinds of other extra chips that were involved in the boards were more complex.
And because of the ways that the 1802 multiplexed its lines, it was able to do more within the chip,
and it actually used the chips for memory, the lines for memory addressing, and the lines for
input output were common lines, and it multiplexed those lines, and depending upon what another pin was,
you could gate that to be used for the memory as well as for the input output lines.
So it was a simpler chip, as far as board design and thusly cheaper, as far as board design.
Built that board myself, and at least I think that the 1802 chip, well, there was a,
there was already a 40-pin connector on the board, and there were a few parts that were
pre-mounted on the board, and then you had to add the rest of the parts yourself, as I remember.
And so I built that myself. Ironically, that was also my first multi-media computer,
because there was a strange program that I found, and you find these programs every month,
the electronics magazines, and this is even before byte of the computer magazines themselves,
or right about the time, maybe that byte was first starting up. And so you would find these
programs, though, for these things, and in magazines that you could get, in articles you would see in
the magazines, and I found a program that there was an input output line on the board, a single bit line,
and you would connect a piece of wire to that single line, and what this program would do,
and you had to hand-enter these on a hex keyboard that was on there. Now, when I say a hex keyboard,
there was a little keyboard to the only input output that was display or keyboard for this,
was a small, you know, hex keyboard that was four by four, if I remember correctly,
so it wasn't quite like a T9 keyboard, but it was something like that, right? To enter in hex values,
everything was in machine language. There was no assembler, at least additionally, for the 1802,
that was available, right? Little would a assembler do you any good, because there was also no
after keyboard or way to hook up a video, you know, terminal to this, even if you had one.
You could, at this point in time, this was back when Don Lancaster was selling his book,
Like Hotcakes, which was the TV, what was it? The TV typewriter book, I believe it was called,
which was a teletype that you could build yourself, essentially, a keyboard and driver for the
Vennio, you could hook up a monitor, regular monitor, black and white, or green screened to this,
and you could use that to do entry of programs into things with higher order languages at the time,
but otherwise you had to have a teletype machine, a Model 42, I believe it was,
Western electric teletype machine, which was a big gigantic mechanical device,
think of it as an electric typewriter on steroids, right? It was literally what they would use
at Western Union to send and receive telegrams, and the teletype machine used RS-232,
it used a current loop address, I forget what the standard was for that, but you could get that
hooked up to your computer at the time, and it had a big printer that would out results,
and you could type in your program there, there wasn't even tape drives at this particular point,
you would type things in, and the advantage of the teletype also was it would have a paper punch
machine to punch paper tape, so you could have your program on paper tape, and then you could keep
those paper tapes and read them through with the reader to load your programs. The 1802 was
an advantage because it had next keyboard, you know, on the original MITF computer, it was switches
in the front, you'd flip switches, you're eight bits below you wanted it, and then you'd flip a
switch to, you know, store that in your memory, and then you go on to the next byte, you'd flip your
switches for your bytes. I mean, we're talking way back here guys, machine language programming,
if you've never done real machine language programming on an 8-bit computer, the way you would jump
back, talk about spaghetti code, the way you would actually jump back is you would jump forward
far enough that you looped around for the 8-bit address space and came to the address space that's
behind you, but you were actually like going into the future and it took you into the past,
like a Star Trek episode or something. So I laboriously typed in on the hex keyboard this
program, and it would turn on and off the single bit that had the connector that the wire was
hanging off of it, right? And you'd set an AM radio next to the computer, and you'd, of course,
have to, as part of your Hex, you'd have to put in some values in the very limited, I think there's
maybe 4K of memory on this machine, which was advanced for the time, and the 4K of memory would not
only hold your program, but it also would hold your values for whatever it is you were going to play,
and it would turn on and off the single bit fast enough to provide an AM signal that would then
kind of like, it was like tuned static, hey, guess, it would turn on and off the single bit to
provide an AM signal that would play whatever tune you had programmed in on your AM radio.
So it was my first multimedia computer, it was capable of playing music.
I think that's probably long enough for this first episode. My first computer, the Cosmic L-1802,
I eventually got an expansion memory board for that, but by the time they came out with any kind
of video output and all those kinds of things I had moved on to another computer that actually had
a keyboard and video out and things like that that was affordable enough for a college student
to be able to work with at the time, but we'll leave that for another episode.
So this is Mr. Gadget signing off, and you can come out and see things about me at Mr. Gadget.com.
I am Mr. Gadget on Identica, I'm Mr. Gadget on Twitter, and you can send me
email at hacker-public-radio or hpr, either one at Mr. Gadget.com.
I welcome interacting with you and look forward to leaving some other phone messages with other
things about my historical past. And with that, this is Mr. Gadget signing off from
Camp City, Missouri. You'll be careful here, you're out on the Technological Frontier,
and I'll be trailblazing very ahead of you. Bye now.
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