Retro Recreations Hack Chat

For when "buy vs. build" is no longer an option

Wednesday, March 17, 2021 12:00 pm PDT Local time zone:
Hack Chat
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Tube Time will host the Hack Chat on Wednesday, March 17 at noon Pacific.

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Nostalgia seems to be an inevitable consequence of progress. Advance any field far enough into the future, and eventually someone will look back with misty eyes and fond memories of the good old days and start the process of turning what would qualify as junk under normal conditions into highly desirable collectibles.

In some ways, those who have been bitten by the computer nostalgia bug are lucky, since the sheer number of artifacts produced during their period of interest is likely to be pretty high, making getting gear to lovingly restore relatively easy. But even products produced in their millions can eventually get difficult to find, especially once they get snapped up by eager collectors, leaving the rest to make do or do without.

Of course, if you're as resourceful as Tube Time is, there's another alternative: build your own retro recreations. He has embarked on some pretty intense builds to recapture a little of what early computer enthusiasts went through trying to build useful machines. He has built replicas of early PC sound cards, like an ISA-bus AdLib card, its MCA equivalent, and the "Snark Barker"-- or is it the "Snood Bloober"? -- which bears an uncanny resemblance to the classic Sound Blaster card from the 1980s.

Tube Time will join us for the Hack Chat this week to answer questions about all his retro recreations, including his newest work on a retro video card. Be sure to bring your questions on retro rebuilds, reverse engineering, and general computer nostalgia to the chat.

  • Hack Chat Transcript, Part 2

    Dan Maloney03/17/2021 at 20:19 0 comments

    tubetime1:04 PM

    and even (get this) a sound card, using the CGA composite video output as a sound output :)

    tubetime1:04 PM
    but i gotta get it working first, lol.

    tubetime1:04 PM
    any more questions about any of this stuff?

    niksgarage1:05 PM
    what are you going to use for the analog end ? palette /dac

    Kevin1:06 PM
    Sounds like some fun projects. I was thinking at first this was going to be more vintage hardware rather than this more "modern" stuff. ;)

    tubetime1:06 PM
    @niksgarage right now it is just a resistor ladder DAC. it's not great but it's better than i thought it would be

    tubetime1:07 PM
    the palette will be done using block RAM in the FPGA

    Kevin1:07 PM
    @tubetime What FPGA device(s) are you using?

    charliex1:07 PM
    it's super interesting project , though i'm getting ptsd remembering all the various modes to support

    tubetime1:07 PM
    there are some tricks to it, like the palette DAC is also a dual port memory

    tubetime1:07 PM
    @Kevin it's an ICE-40

    tubetime1:07 PM
    @charliex i'm not really looking forward to the complex beast that is EGA

    Thanks all, transcript coming up. And don't forget to tune in next week for Mitxela and MIDI:

    tubetime1:08 PM
    thanks for hosting @Dan Maloney and @Dusan Petrovic

    charliex1:08 PM
    @tubetime i feel you

    Kevin1:08 PM
    @tubetime Are you publishing information on your projects somewhere other than Twitter?

    tubetime1:09 PM
    @Kevin yes, i also have a blog that i sometimes update:

    tubetime1:09 PM
    right now the lead article is my Twitter best-of threads lol

    Kevin1:09 PM
    ok, ty. I don't use Twitter or Facebook

    tubetime1:10 PM
    for me, i use twitter because it's a very low friction way of posting project updates

    tubetime1:10 PM
    i can bust out the phone, snap a photo, tweet it with some text, maybe tack it onto an existing thread, and it just works and it doesn't slow me down

    tubetime1:10 PM
    for the blog i have to download the images, process them to shrink them down, then upload them to the wordpress, edit the article, blah blah

    tubetime1:11 PM
    takes like an hour that i'd rather spend on the project itself :)

    Kevin1:11 PM
    I wouldn't have thought it takes that long but there is a difference in doing real time posting of work in progress vs. documenting work done over a longer period of time.

    Kevin1:12 PM
    I mostly put up information about projects after major milestones.

    charliex1:12 PM
    yeah wordpress needs a twitter like thing so i can record and add to a post quickly for notes, especially when you go back to later after a long session and dont always remember the procedures you did, sometimes i've done a thing twice just to document it

    charliex1:12 PM
    the struggle is real

    tubetime1:13 PM
    or really, any site dedicated to hosting projects could use something like that. maybe a phone app

    tubetime1:13 PM
    trying to think if i know any sites that would be good for hosting projects...

    charliex1:13 PM

    charliex1:13 PM
    not til they add export/backups, perhaps?

    tubetime1:14 PM
    @Dan Maloney oh see there you go!

    charliex1:14 PM
    ^ see my comment heh

  • Hack Chat Transcript, Part 1

    Dan Maloney03/17/2021 at 20:18 0 comments

    OK, I guess we can kick it off now. Welcome to Hack Chat everyone, I'm Dan and I'll be moderating today along with Dusan for Tube Time, who joins us to look at the ins and outs of building your own retro sound cards and such.

    Good afternoon, Tube Time -- have you joined the chat yet?

    tubetime12:01 PM
    yup, right here!

    AH, cool. Welcome aboard!

    tubetime12:01 PM
    thank you.

    Dusan Petrovic12:01 PM
    Hi and welcome all.

    I was just looking at the electron gun cross-sections on Twitter. Cool stuff, I used to pull electron guns out of old tubes when I worked in a TV repair shop.

    tubetime12:02 PM
    yeah they're tricky little beasts to design, there's a fascinating story about that.

    tubetime12:03 PM
    you can use geometric methods using drafting tools, which is often what they did with optics back in the day as well

    tubetime12:03 PM
    but one trick they did was to build the lens out of conductive pieces of metal and mount them on top of conductive carbon paper

    tubetime12:03 PM
    then you could apply a voltage across the pieces of metal and measure the field strength at various points on the paper

    tubetime12:04 PM
    a similar method involved a 3D mockup of the tube elements that were placed in a bath of conductive fluid (salt water, for example). then you could put a probe electrode at various points inside to measure the field

    tubetime12:05 PM
    i was going to say that's a bit tangential to today's topic but it's also where i got my handle from!

    It's amazing to realize that every livingroom in the world once had a small particle accelerator in it, strictly for entertainment purposes.

    tubetime12:06 PM
    people often think it's because of audio tubes or amplifiers or whatever but i really like CRTs and nixie tubes. and a few other weird obscure vacuum tubes. audio tubes are...ok, but not my major focus.

    Nah, all this stuff is too cool not to dive into. That live stream you did with the old Ikegami camera was great, BTW

    tubetime12:06 PM
    that's sort of the tie in with my retrocomputing hobby. i like the CRTs and i grew up using the computers, so this is a way for me to extend that

    tubetime12:07 PM
    ahh thank you, that was fun. i need to calibrate it again because i have another project in mind for it involving my Amiga Toaster Flyer hard disk video recorder from 1995

    tubetime12:07 PM
    anyway i grew up with old Amiga and PC hardware in 80s and 90s, so i have a nostalgic attachment

    tubetime12:08 PM
    but some of the hardware has gotten harder and harder to find, and in many cases, collectible and therefore quite expensive!

    Bharbour12:09 PM
    Any interest in old VME stuff?

    tubetime12:09 PM
    at some point a few years ago i wanted to get my hands on an Ad Lib sound card for an old XT computer, and i had trouble finding one that wasn't $$$

    And thus we come to today's main topic!

    tubetime12:09 PM
    nope, never did VME.

    tubetime12:09 PM
    anyway i was doing some research and i realized that the board itself was just a simple 2-layer design, and i could see nearly all of the traces

    tubetime12:10 PM
    i also found Sergey's ad lib clone design that he had done

    tubetime12:10 PM
    but it was really small and didn't look at all like the original. that's what kicked off the reverse engineering project

    tubetime12:11 PM
    it took a bit of trial and error but i figured out that the original images didn't have too much distortion--meaning that if i knew the dots per inch, i could calculate precise distances between components, trace lengths, and that sort of thing

    tubetime12:12 PM
    the basic idea is to take a chip footprint with a known pitch (0.1") and then measure the number of pixels from end to end, and divide by the spacing

    tubetime12:12 PM
    that factor gets entered into GIMP (which i use for image editing) and so it displays coordinates in inches which is quite convenient

    So you didn't so much as build a working version of the card, but a detailed replica

    tubetime12:13 PM
    yes, my goal was to match it as closely as possible so that i could fab one up...

    Read more »

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