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Thread: TRS-80 Model II acquired.

  1. #1

    Default TRS-80 Model II acquired.

    Good evening, gentlemen. Happy Tuesday.

    I've finally acquired a Model II with a keyboard (assuming it survives shipping). My intention is to install a Model 16 M68000 card, study up on the hardware manual and try to make a 4Mb (or more) SRAM board, put some sort of fixed disk (preferably emulated) in it, and get it running Xenix 3.

    I have no 8" media whatsoever, so I have a GoTek with the FlashFloppy firmware on the way.

    I don't have much experience with TRS-80s, so I have a few questions (which I hope aren't too stupid, lol).

    1. Web surfing indicates that the GoTek will work with the Model 6000, when the FlashFloppy firmware is installed. I assume this means it will also work with the Model II?

    2. What might be the least financially stressful way to get Xenix-compatible fixed storage on one of these machines?

    3. Any gotchas I ought to be watching out for?

    Thank you, gentlemen. I think this will be a really great project, and fun to make YouTube videos about. I've been sniffing around Big Tandies for a while, and it's quite exciting to finally have one coming.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, box of 8" floppy disks, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  2. #2
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    Fun! I don’t know much about the big Tandys, but designing a RAM card sounds like a good time!

    I think the TL;DR when it comes to 8” floppy drives is they basically look like 1.2MB PC floppy drives in terms of rotation/bitrate. The Model II’s original drive is single sided, but I don’t think that should be a dealbreaker. (And I think it supports double sided drives anyway, although I don’t know if there are any gotchyas booting from them or whatever.)
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  3. #3
    Join Date
    Jan 2012
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    Nice find Lee. Looking forward to your model II videos. I have a model II i got from Radracer203. Doesnt power up and. Had no keyboard. I finally found a kb this year for a fair price. Maybe your videos will give me the motivation tofix it. I have a bunch of 8" floppy disks. Send me a Pm and i can msil you a few to get started.

  4. #4

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    Well, I have neutral news and bad news.......

    Bad news first: https://imgur.com/a/YHRsz4V

    Neutral news is that it still behaves as expected when powered on, though I haven't checked the keyboard. So perhaps I can repair the case damage.

    I try not to complain in general, but mannnnnnnnn..... This sucks. I should have pressured the guy harder to go in for pro packing, but he assured me that the packing job was more than adequate. I mean, I don't mean to cast aspersions at the seller. He obviously put significant effort into the packing, but he just didn't know how to pack heavy fragile items. It just breaks my heart when grand old boxen get turned into junk.

    I bet I can fix the plastic. Fill any missing places with wire mesh and then bondo over and sand and paint. Any recommendations on a particular epoxy for all the cracks and broken off bits, or anything else?
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, box of 8" floppy disks, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  5. #5
    Join Date
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    you gotta be kidding me.. this is becoming the order of the day. I just got a monitor in that came shattered. People just don't know how to ship antique plastics and CRT's (which usually go hand in hand). Well I think you can glue it all back together like a puzzle. I have done it before. Thankfully the main structure seems intact its just superficial stuff.

    The top vent area. Fix the perimeter but maybe sand the area where the vent louvres used to be and install a metal mesh from underneath. IT would match up after painting.

    Thats a damn shame, but if its still at least working you can continue with the Sep-Tandy videos. Fix the Aesthetics at your leisure.

  6. #6

    Default

    Quote Originally Posted by VERAULT View Post
    you gotta be kidding me.. this is becoming the order of the day. I just got a monitor in that came shattered. People just don't know how to ship antique plastics and CRT's (which usually go hand in hand). Well I think you can glue it all back together like a puzzle. I have done it before. Thankfully the main structure seems intact its just superficial stuff.

    The top vent area. Fix the perimeter but maybe sand the area where the vent louvres used to be and install a metal mesh from underneath. IT would match up after painting.

    Thats a damn shame, but if its still at least working you can continue with the Sep-Tandy videos. Fix the Aesthetics at your leisure.
    I can't really do much testing until the floppy emulator gets here on Saturday anyway.

    I may be able to 3d print a replacement piece for the top vent. That will be a hell of a learning curve all the sudden, as I'm not a 3d modeler, but I guess I have to start somewhere. Lol.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, box of 8" floppy disks, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  7. #7
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    Yeah I got to dive into the 3D printing world myself. The only thing that is putting me off/ intimidating me is learning the modeling software. I was pretty intrigued by one of Ben Hecks last video showing a $150.00 decent 3D printer.

  8. #8

    Default

    Quote Originally Posted by Eudimorphodon View Post
    Fun! I don’t know much about the big Tandys, but designing a RAM card sounds like a good time!

    I think the TL;DR when it comes to 8” floppy drives is they basically look like 1.2MB PC floppy drives in terms of rotation/bitrate. The Model II’s original drive is single sided, but I don’t think that should be a dealbreaker. (And I think it supports double sided drives anyway, although I don’t know if there are any gotchyas booting from them or whatever.)
    I need to study the schematics a little more closely, I think. I just read something on the web that says the Model 16/6000 maxed out at 1mb of RAM. But I thought the M68k had a 24 bit address bus, so it ought to be able to address 16 meg. Maybe their funny ram connector thing doesn't expose all the address lines, or maybe it's a ROM thing or... I dunno.

    My first thought was to make a card with SRAMs on it, that plugged straight into the headers on the CPU card instead of using the ribbon cables, and thus save a precious expansion slot in the cage. But I guess there has to be a shared RAM segment with the z80 (something else I need to read more about), which will probably require connection to a slot in the card cage after all. And will make the circuit a little more complicated. Ah well, I recall there being good schematics for everything in the Model 16 technical manual, so that will make some amusing bedtime reading I reckon.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): Tandy 1000 EX/HX power supply, box of 8" floppy disks, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  9. #9
    Join Date
    Jan 2012
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    Connecticut, USA
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    3,017

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    So this 68K card you want to install to run Xenix, Is it just a stock card Tandy made once upon a time or do you need to build one?

  10. #10
    Join Date
    Aug 2020
    Location
    Baton Rouge, LA
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    9

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    Quote Originally Posted by VERAULT View Post
    you gotta be kidding me.. this is becoming the order of the day. I just got a monitor in that came shattered. People just don't know how to ship antique plastics and CRT's (which usually go hand in hand).
    Tell me about it. The Zenith Supersport I ordered arrived in a PLASTIC BAG with the PSU thrown in. Case got beat to hell and back but surprised it wasn't worse. Seller did give me a full refund though. But still, these old things aren't growing on trees!

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