• EEVblog #32 – Tandy 1000 Retro Computer time!

    Dave goes Back to the Future and powers up his old Tandy 1000 computer.
    Will it work?, will it choke?
    And how to channel your inner Woz to design your own Turbo Board.
    (Check out the ROM BIOS version 1.00.00 !!)

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      • Alexandria Carmichael

        If it was working before it was put in a reasonable storage place, I say yes!

      • Roger

        Maybe the problem with the first switch on was the PSU electrolytic capacators, or the cap in the reset circuit…

        Now it’s running, give it a job to do! Mke it into a clock or something…

        How about an episode on FPGA’s, are they usable by a non professional? What does the programming look like?

        Great podcast dave, I really enjoy them, keep them coming!

        • Jeff Nichols

          I’d also like to see an episode on FPGAs. Every site on the web about FPGAs gives a great overview of what they are and how they work internally, but they never tell you what they’re good for or when to use them.

          • Lionel

            Another vote for a blog entry on FPGAs. I’d love to hear an overview on what they’re good for, & the “gotchas” associated with them.

      • Kathy Quinlan

        Hi Dave, great blog, reminded me of my first PC, it was a fully pimped XT, my parents bought it so dad could work at home. I liked drafting back then so my parents bought me AutoSketch V1.0 (we did every upgrade till V5.X) then I found EasyTrax and I was in love 😉

        It was slow, needed more ram, and a HDD, the HDD was easy, parents handed over plastic card and I was resented with a box wooohoo 20MB HDD with controller, the ram was a bit more of a problem as not many expansion cards existed back then, but I found an article in a magazine, it involved soldering extra ram chips on top of the existing ones with a few pins bent out and jumpered to a PCB with the extra address decoding, I was surprised at age 12 I was allowed to do this on “the family computer” but after a bit of work and a few days trouble shooting it worked 🙂

        The speed mod was found in EA IIRC it was written by you I guess as the circuit was the same 🙂 mine was not needing to be so small as the clock chip was under the drive bays (my PC was an XT clone with a full sized case that hinged up at the back) also added a reset switch 🙂

        Wow what memories, as I made friends in the computer industry, the machine slowly grew up to a 486Dx2 66Mhz with a 250Mb HDD, network card (arc net) and a VGA monitor (the original was CGA).

      • Michael Thompson

        I agree that hardware should be re-purposed.
        Find it a job it can do until the end of it’s functional life.

        This blog is always entertaining and informative!

        The intro was snazzy!

      • kipman725

        Nice mod. FPGA artical would be good, mabey your veiws on the various languages used and how blocks of code are meant to interact! I have done some fpga stuff but found it ticky to get anything more complex than pong working.

      • Born in 1985..

      • Hi Dave,

        Great blog, I can’t wait till your next blog is online 🙂
        I like your new intro too.

        Keep up the good work.
        Need any help or info with your blog, let me know.

      • David

        Dave, Great Blog! It keeps me entertained without making me feel overwhelmed ( I am only into my 2nd year of a Computer Engineering degree).

        The new intro is a bit cheesy with the graphics but in a good way. The geek in me loves that it is an actual chip and that you know what it is; ie no canned public domain image.

        I will eventually have a class dedicated to FPGA and would love to see an intro into it. Maybe even a series about it with a simple project using an emulator of some sort.

        Keep up the good work, I can’t wait on the next post!!


      • Intro is cool, keep up the good work.

      • Arthur

        Man, your blog is great.
        Keep it running.
        You have reached Brazil !

      • Wow! That’s right. Some people where not even born then. I still have my first and second computers (Mac + HX20) from the those “1984” days. It has been that long.

      • Wow, animating with Altium! They really do want it to do everything for everyone!

      • Kathy Quinlan

        OT comment….

        Love the guest appearance in the webinar Dave 😉



        • Huh?
          What webinar?

      • Kathy Quinlan

        Hi Dave,

        The Altium FPGA embedded instrument Webinar that Marty did this week 🙂

        There is a still shot of you with a NB a PCB and the three monitors 😉



        • Obviously some random guy that just happens to look like me, I get that a lot!
          Let me guess, he looks stupid like he doesn’t know what he’s doing with that hardware? Probably just a marketing guy or a paid male nerd model.
          I’ll have to investigate this egregious attempt to cash in on my image :->

      • Kathy Quinlan

        Lol Dave,

        It is a dead ringer for you 😉

        I would ask for your royalties lol

        The image was used for a worldwide production lol

      • Brian Hoskins

        I never went the PC route in the beginning. Indeed, back then the PC was very much inferior when compared to alternatives. The Amiga in 1985 revolutionised the computer world, and were it not for the blundering idiots that managed Commodore I think we would all be using Amiga computers today. Or at the very least, Amiga would have easily displaced the MAC.

        But, times move on and it just goes to show that the *best* product isn’t always the winning product. It all comes down to marketing in the end, and Commodore management were very poor at that.

        Good blog. I love firing up my old computers. This inspired me to get my old Spectrum out of the attic, and it actually worked first time!!! Impressed! 🙂

      • Brian Hoskins

        Encouraged by my Spectrum success I decided to get some of my old Amiga computers down today. My A1200 and my CD32 worked fine first time, but the A500+ reports an error at reset and my CDTV fails to power on at all.

        I’ve opened the A500+ and a battery for the clock has been oozing its innards out all over the motherboard. We’ll see what happens once I’ve removed the battery and cleaned the board!!


      • Ross Vumbaca

        Hi Brian,

        Finally someone mentions the Amiga! Truly a superior computer at the time, I have the whole collection now :-).. Love the fact that the manuals came with schematics too.

        The leaking battery issue is a common problem, you need to remove them from all your Amigas before storage, or the leaking gunk will cause serious damage! So far nearly all my Amigas from 85-94 are still working..


      • Wait, I might have missed something…

        You mentioned that they were using an external crystal even though an internal oscillator was present on the chip. You mentioned that you might be able to use that internal oscillator when you were first investigating a solution.

        Was the internal oscillator also running at 4.77? Then you just swapped the external one for a 20mhz? So the factory mode (external crystal) became 20mhz and the overclocking switch really enabled the 4.77mhz internal one? I guess you built an UN-turbo switch! 😀

        And did you really have the processor overclocked to 20mhz back then? WOW!!

        • The internal oscillator circuit required the external crystal, sorry for the confusion. Almost unheard of back then to have a chip or micro with an actual full internal oscillator, unlike these days.
          The 20MHz external crystal got internally divided, as did the other external crystal input you could switch too, so the processor switched between 4.77MHz and 8MHz.

      • Dave,
        If you think there’s “so much waste” in the EE hardware world, you should see what’s happened to the software industry.

        This past week, I was up on the attic and spotted my old TRS-80 Model III sitting there and was really tempted to do what you’ve done and get it out. I think you’ve inspired me to use up my next free day messing with it. When I was very young, like middle school age, I wrote a Z80 Disassembler so I could hack the ROM based OS of the thing! Great memories. Back then, instruction set docs described the instruction with a graph and showed all the timings as an annotated image. Those manuals are still up there.

        Sadly, In spite of my interest in hardware, I’ve always been stuck in the software world. I do a little hobby electronics and that’s it. If I ever get so rich I have money to burn, I’d love to go back to school and get a EE degree. Don’t even ask me why… I guess I just love the stuff and I know I suck at hardware! (as the blog says)

      The EEVblog Store generally ships twice a week, on Tuesdays & Fridays, Sydney time. Dismiss