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  1. R

    Advanced Digital Corporation Super Six TurboDOS and TurboDOS x86 PC - can they communicate ?

    I've been gradually building up some TurboDOS systems. I now have a 3 terminal ADC S6 with 1 master and 2 slaves running Z80 TurboDOS and a 386 PC running TurboDOS PC. The 386 has a traditional serial card set to COM1 which I have no clue if TurboDOS PC is even aware of it. I only have 3...
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    Miniscribe 2012 MFM hard drive with stiction and bearing noise

    I accidentally posted this in the vcwiki hardware forum which nobody seems to read I powered up a Miniscribe 2012 which at first didn't spin up then seemed to have varying speed but now steady and the spindle bearing noise seems to have become less. It did eventually prep and pass a media test...
  3. R

    Miniscribe 2012 stiction and bearing noise

    I powered up a Miniscribe 2012 which at first didn't spin up then seemed to have varying speed but now steady and the noise seems to have become less. It's currently prepping and doing a media test on a Zenith Z100. If I can find access to the spindle bearings without opening the platter...
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    Does a Seagate ST-225 need to be parked ?

    I have a 486 ISA slotted board with an original IBM AT hard/floppy controller connected to a Seagate ST-225 just running DOS or whatever. To preserve the media should I be parking the drive before powering off or does it auto park ? Does it matter ? If so is there a park utility ? Larry G
  5. R

    Does a Seagate ST-225 require a data separator ?

    I'm trying to get a hard drive running on my ADC Super Six setup. I have a Monitor Dynamics HDC-1013 controller trying to interface with a Seagate ST-225 drive. The MD card has a data separator piggybacked on it. I assembled a test program provided by MD and get correct responses from the...
  6. R

    QumeTrak 842 stepper motor bad?

    I just purchased a dual 8" enclosure and drives from eBay for my CompuPro. Both are QumeTrak 842's. One seems to work fine but the other never seeks backwards. If I home the head to track 0 it reads the directory and will run a program but will not run the next one. It seems to never reverse...
  7. R

    looking for documentation for Sritek 68000 MicroCard

    I recently acquired a NOS Sritek 68000 MicroCard with software drivers but no documentation. It was featured in Byte Magazine July 1984. It's a 68k coprocessor card with 2MB of ram. It could run Xenix on an IBM XT or AT. Does anyone have a manual for it? Larry G
  8. R

    Astec power supply AA11040B ticking problem when cold

    This one has me stumped. I have replaced all caps and still have the same symptom. When I power on with just a bare II+ or IIe (no cards) it will just tick for awhile (maybe a few seconds)then beep and boot ok. The more load I put on like adding a memory card, the longer it has to warm up before...
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    Mitsubishi M4853 floppy drive head load sticks

    In the quest to add a mini floppy drive to my CompuPro 816, I took a chance and purchased a Mitsubishi M4853 drive advertised as NOS but untested, as is. The drive does look brand new and works great BUT (with old equipment, there's usually a BUT) after the head carriage is raised to put in a...
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    CompuPro DISK1A boots but not with CPU 286 card

    I have been searching for a DISK1A floppy controller for my CompuPro 8/16 for almost 2 years until I recently purchased one on Ebay. I had to solder in 3 7805 regulators to convert the power for my system. I just got it to boot Concurrent CP/M 3.1 !! Here is a video: https://youtu.be/_huYgwB1p9A...
  11. R

    How to turn on notification of thread activity?

    Is there a way to get notified of activity on a certain thread? Some of these go dormant for months and it would be good to get a heads up notice. Or is that what "subscribe to this thread" means?
  12. R

    My saga of building and troubleshooting an Apple II Plus from scratch

    This all started with a collection of parts I received in the 90's from a retired high school electronics teacher. Included was a nice shiny Apple II+ motherboard in an opened original box. Something is very wrong in this photo. Can you see it? I did not see the problem when I took this picture...
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    Should I do a blog or start a thread?

    I have assembled an Apple II+ from parts and have a whole sequence of events with pictures and problems that occurred and been fixed but now have a current problem seeking technical advice and will report back if fixed. Actually two discreet problems. Is this best done with a blog? Do individual...
  14. R

    How To Do A Flyback Ring Test With An Oscilloscope

    The topic has been brought up a couple times so I did an experiment with what I remembered from doing this testing years ago on flybacks. The biggest requirement is an oscilloscope that has a horizontal gate output usually on the back of the scope. For this test, I used an Apple //gs color...
  15. R

    Zenith Z100 VGA Color Success Story

    Evidently Zenith Z100 9 pin color output is the same signal and pins as IBM CGA. I used the same setup to test this as I did with CGA. I used the video DAC from here: http://bit-c128.com/ coupled to a GBS-8200 scan doubler. On the Z100 video board, I set jumpers to positive H and V sync (also...
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    is memory parity necessary ?

    So I'm digging around in stuff I acquired and found a Z-205 256k memory card for my Zenith Z-100. I installed it and after running the Zenith disk based memory diagnostics and replacing some memory and reseating others, it passes all the memory tests except parity: It gives a list of chips as...
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    Write Precompensation Adjustment for Zenith Z-100 needed for formatting errors

    As I mentioned on another thread recently, I was having issues with formatting both 8 inch and 5 inch floppies. The 8 inch would appear to format correctly but then give me a FAT error when I attempted to copy files to it: Then when I formatted 5 inch floppies, I would get an error at track...
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    How to disassemble and clean Apple IIe game paddles

    The contact in the pots of my game paddles are pretty much non-existent. Is there any photos / explanation of how to get them open? There seems to be a screw under the label at the handle. I would like to get them open far enough to at least get some cleaning spray inside. Back in the day, I...
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    Apple II Graphics Tablet ROM found

    Many years ago, an electronics teacher from a neighborhood high school would bring in items for repair at the shop where I worked. He also supported the schools Apple II computers. When the school switched to later model computers, he acquired the remaining Apple II parts inventory. He...
  20. R

    bad video ram in Zenith Z-100

    I was noticing pixelated video in my newly acquired Zenith Z-100. It has a version 2.5 ROM with built in diagnostics. I set it to manual boot and got to the diagnostics test menu by pressing T. Here is the pixelated menu: Pressing C generated a color bar pattern which also revealed the problem...