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  1. M

    TRS-80 Model I horizontal video instability

    I'm super impressed that you went through all this debugging. Personally, the capacitors on there are decades past their life span. I would consider them to ALL be bad and necessary to replace. I usually do that for any system before turning the power on. I mostly collect mini-computers though...
  2. M

    DEC PRO380/VAX Console real time interface.

    Do you still have the VAXconsole hard drive? I have an 8550 and haven't been able to find the VAXconsole software for it. Without an image of that drive, the machine cannot be booted and is a very large brick.
  3. M

    Disk Change / Ready Signal on Model 4

    I'm using a 3.5" drive on a TRS-80 Model 4 as an external drive. I'm doing this with LS-DOS 6.3.1 and it works completely fine. I find posts all over the Interweb stating that you need to find a jumpered drive, so that you can disable the IBM PC disk change hack. This hack is suppose to make...
  4. M

    PC-38N, VAX Console, PC-380 (Pro 380), RTI Interface Needed for VAX 8550 Restoration

    I've recently started restoration on a VAX 8550 in beautiful condition. This machine requires a PC-38N (I believed alternately labeled a "VAX Console") to boot. It appears a PC-38N is a PC-380 (Pro 380) with an RTI (real-time interface) board and special boot software required by the 8550...
  5. M

    PDP 11/23 Halting Every Instruction

    I've recently attempted to fire up a PDP-11/23 that I acquired many years ago. I just never got around to firing it up and getting it working. But I'm at my wits end here after working with it all weekend. I'm now down to a pretty bare bones configuration: Slot 1 AB, M8186, Board Revision...
  6. M

    Data General Nova 3

    I've been searching for information about the DG Nova 3 bus. Does anyone know what bus this has and have any links to information about the electrical specifications of the bus? Does the bus architecture have a name that would be helpful? Thanks!
  7. M

    Problem booting a KA660-A (VAX 4000-200)

    I have a working VAX 4000-200 and bought a spare CPU board for it. I plugged in the spare board and it seems to hang when starting the OS boot process. I've included the log below. I looked through the KA660 technical reference and couldn't find what might be hanging at this point in the boot...
  8. M

    VAXserver 4000-200 to VAX 4000-200

    Does anyone know if it is possible to convert a VAXserver 4000-200 to a VAX 4000-200 by simply replacing the EPROMs or is there a genuine difference in the CPU board? If not, what are the limitations of the VAXserver and how are they enforced in VMS?
  9. M

    Dumping a KA53 (VAX 4000 105A) system rom

    Lately I've been trying to dump my VAX system ROMs in case the EPROMs or EEPROMs suffer bit rot. The KA53 (i.e. VAX 4000 105A) doesn't have EPROM chips on the motherboard, so I was attempting to use the boot console's "examine" command to grab the system ROM contents. This has worked before on...
  10. M

    VAXstation 3100 M38 Memory Test Code

    When I boot my VAXstation 3100 M38 I get the following: KA42-B V1.3 F...E...D...C...B?.. etc. Note the B?, which indicates a memory error. Running TEST 50 shows the following: ?? MEM 000C.0200 00C00000 Which indicates 12MB memory, which matches what's in the system. However, the...
  11. M

    PDP-11/23 and H9276-A

    I have a PDP-11/23 which I thought maybe I could upgrade using an H9276-A backplane. Actually, I have lots of enclosures I could use. Could I use an KDJ11-BF with this backplane and make an 11/23 PLUS? Any help getting started in that direction would be very useful to me. Basically, I guess...
  12. M

    TU80 and TU81 R/W Heads

    I have a very nice TU80 and TU81 that I'd like to get working again. The problem is, the heads on both look pretty worn. One looks like it's seen lots of hard use and the other looks like it was stored under water. Is there any chance that anyone here has spare heads for one or both of these...
  13. M

    Q-BUS Video Card for VAX 4000/200

    I have a VAX 4000/200 which is entirely Q-BUS. I'd like to know if there's a Q-Bus video board that one can use on this machine, kind of like you'd do with a VAXstation.
  14. M

    My PDP-11/23

    Starting to work on my PDP-11/23. It's a pretty basic machine but in very clean shape.
  15. M

    Computer Products NFS50-7608 Power supply

    I have a Computer Products NFS50-7608 power supply which is missing some components. I'm wondering if anyone has one of these (it's a 40W, -12V, 12V, 5V, I think). If so, I'd like to get some photos to help me fill out the missing components. Any help would be greatly appreciated!
  16. M

    Wire Wrap Socket Selection

    So, I was going to order some wire wrap sockets for prototyping a disk controller for an old system. I went straight over to Jameco where they’re quite pricy, especially for the gold ones. So I googled it and found these guys...
  17. M

    Misosys MSCSI Drvier for LDOS 5.3

    I have a Misosys SCSI interface which came with the MSCSI6/DCT driver. That is, a driver for LS-DOS 6.3. The manual mentions there's also a version of the driver that was available for LDOS 5.3 but was on a separate disk and sold separately. I'd really like to find a copy so that I can use...
  18. M

    Monthly Seattle Retro-computing Society Meeting This Weekend (August 25th)

    Come one, come all, to the Seattle Retro-Computing Society's regular monthly meeting! It will be held Saturday, August 25th from 11:30 AM to 5:00 PM. Do you do any of the following with old computers? Will you be near Seattle on Saturday? + Use, collect, and/or restore them + Play games...
  19. M

    Differences in Monochrome 12" CRT Monitor Tubes

    So, I have two tubes that I wanted to see if they were interchangeable (12VCMP3 and R12CPDB). So, I started on a Google quest to get specifications for the two tubes. I can't find anything! I know the 12VCMP3 is a Green 12V 12" tube. I know the R12CPDB is an Amber 12" tube. But, beyond that...
  20. M

    Seattle Retro-computing Society Meeting Again this Weekend!

    The monthly meeting of the Seattle Retro-Computing Society is on for this weekend! Tell all your friends! The SRCS gets together on the fourth Saturday of each month at the Living Computer Museum, from 11:30 AM to 5:00 PM. For more information, www.seattleretrocomputing.com
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