It was a long road to booting DOS68 on the old SWTPC 6800

Comments · 579

• AD

  @adriansdigitalbasement · 4 years ago · pinned

  I got a nice message from the person who made these original disk images I used to make this work, so I&apos;ll post it here. (And it appears that YouTube did eat the comment!!!)<br><br>&quot;I&apos;m the guy who made the crappy KryoFlux image on <a href="http://archive.org/">archive.org</a> -- awesome video, and I&apos;m glad you were able to make it work! Back when I imaged the disk I was just starting out with KyroFlux and was only familiar with IBM-formatted stuff. I actually found those SSB disks at a swap meet after I had bought the KryoFlux. They were sitting in an old cigar box, and the vendor wanted $15 for them. I hadn&apos;t the faintest clue who Smoke Signal Broadcasting was but found DOS-68 and the company&apos;s name enigmatic. It turns out I was lucky that I purchased them that day, as all the other electronics-related stuff that the vendor had that day (loose PROMs, ancient LEDs, breadboards and a TRS-80 Model I monitor) were gone the next week.<br> <br> <br><br>Sorry for the headache that my 360 RPM 80-track drive caused! At the time all I had was a TEAC 55GFR, which I did all my PC disk archiving on before I found the SSB disks. I was aware of the issue with reading 360 KB disks written from a 1.2 MB drive, but thought that flux imaging would benefit from the finer pitch of the read head of a 1.2 MB drive, in the case of bit rot and other bad sector errors. I never realized that crosstalk is a potential problem! Really I was concerned with the age of the disks (almost 40 years old when I found them) and the potential for sticky-shed syndrome to eventually ruin them, so I just wanted them backed up by any means possible. I was amazed that KyroFlux software detected no errors when interpreting the data as FM encoded, and putting the output disk image into a hex editor looked promising with all the DOS-68 filenames and message strings, but without a 6800 system or experience with emulating one I couldn&apos;t really put those images to the test. I&apos;m glad it worked out perfect, even though it took some effort to correct my mistakes. <br> <br><br>I still have all the disks, including the FORTRAN compilers, and will plan to recreate the flux images with a 300RPM 360K drive eventually (right now they&apos;re in cold storage).<br> <br> <br> <br> <br>--@fleaslikeus&quot;

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• TH

  @The_Wandering_Nerd · 4 years ago

  This operating system makes MS-DOS, CP/M and the Linux command line look like a miracle of user-friendliness and verbosity by comparison. What an amazing piece of history.

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• VI

  @VideoJocky1 · 4 years ago

  Brings back memories. &nbsp;I built my SWTPC 6800 from a kit. &nbsp;Soldered all the components in the motherboard and 4K ram board. &nbsp;I &nbsp;didn&apos;t have a floppy drive, I used a Teletype ASR 33 to load basic from a paper tape.

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• DR

  @Dr_Mario2007 · 4 years ago (edited)

  I think the delay on the floppy disk controller card, either software or hardware, has to do with some older floppy disk drive, as the spindle motors on some of them were huge and heavy, so the controller is simply buying the floppy disk drives time to stabilize in term of speed of the spindle before it even bother to read the floppy disks, mostly to prevent the CRC checksum errors while reading the disk that&apos;s not in the alignment of both rotation speed and MFM subcarrier frequency. Modern floppy disk controller doesn&apos;t do that anymore as we were using the final 3 inches floppy disk drives whose motors were light so it spins up right away.<br><br>So, protip; for those who love computing history and uses 5 inch floppy disk drives, especially those modified to accept the classic MFM datalink, I recommend to incur the three seconds hard drive boot delay in the BIOS, so you can give those classic drives time to stabilize before booting up the OS on it or do anything with it otherwise.

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• BI

  @bitslasher89 · 4 years ago

  It&apos;s funny you said, &quot;I&apos;m more of a hardware guy, and this software stuff is a bit over my pay grade.&quot; &nbsp;I feel the same way watching you, except in reverse. &nbsp;I&apos;m a software engineer trying to learn how to repair old PC hardware (to keep it running)... you&apos;re way beyond my pay grade!

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• GO

  @gordonreeder3451 · 4 years ago

  I actually knew some people back in the day who had these SWTPC 6800 machines. Sure it looks clunky and simple today. But back then it was the best thing ever. Watching this series is a real trip down memory lane.

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• ON

  @onesixfive · 4 years ago

  ive been watching this channel for a couple years. &nbsp;i know i have learned alot because i can always follow along logically with what is going on, even if i dont understand the &apos;why&apos; of a ton of it, nor could i recreate it or explain it to someone else. &nbsp;but the crazy thing is that despite that, and despite the fact that i rarely watch videos 30-60 min long, i always watch these videos in their entirety, never get bored and enjoy every minute. &nbsp;keep doing what you do adrian, you have my support.

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• BA

  @battra92 · 4 years ago

  That BFD was probably a BFD when it came out.

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• KJ

  @kjtroj · 4 years ago

  The problems you worked through demonstrate just how far we&apos;ve come in terms of sophistication on not only the hardware, but also the software in the systems we use. &nbsp;Troubleshooting these old systems is definitely an adventure!

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• DU

  @dukane3k · 4 years ago

  Very fitting for Adrian Black to take over the reins of this computer from Hank White! 😁

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• IC

  @Ice_Karma · 4 years ago

  &quot;STOP=11 CONT=13&quot; looks like the hexadecimal representation of XON and XOFF... but they&apos;re the wrong way around. That is, it effectively says, &quot;STOP=XON CONT=XOFF&quot;.<br><br>&quot;CRT=8004&quot;, you mentioned that the ROM wedged itself into an unused part of the I/O address space, so could that be the CRT controller chip&apos;s (base) address? And could &quot;ECHO=&quot; be the address of a ROM routine to print one (or more) characters?

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• FR

  @freelancer42 · 4 years ago

  What I love about this is that even though the original backup was made with the wrong drive/wrong settings, it was still enough to turn it into a completely usable, bootable disk (with some extra steps). Just goes to show that when it comes to data preservation, doing something is always better than doing nothing. Even if you don&apos;t get it completely right it can still be useful to someone in the future!

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