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Recent content by Ken Vaughn

  1. K

    Free To A Good Home (with conditions)

    This post will be quite long, but it is important to read it carefully. The system is a 1977 vintage IMSAI PCS-80/30 system with two Northstar disk drives and an IDS impact printer (serial interface). First the good news. It is a complete system with everything shown in the first video...
  2. K

    Videos of my 34 year old IMSAI PCS-80/30

    I generated a couple of videos which show my 34 year old IMSAI system. Part one shows the hardware and the three operating systems that I used -- namely Northstar DOS, CP/M, and the UCSD p-code system. I also show my original printer, and a connected modern laptop...
  3. K

    Commodore Plus 4 Found in Thrift Store

    I stumbled onto this in a thrift store over the weekend. Marked $10, but with my 50% senior discount, I picked it up for $5. Came in a box with manuals, power adapter, and TV connection cables. http://home.comcast.net/~kvaughn65c/img_1109.jpg http://home.comcast.net/~kvaughn65c/img_1110.jpg...
  4. K

    5151 high-persistence phosphor ghosting

    I acquired an old IBM 5151 green phosphor monochrome monitor. It works fine, but the ghosting is more pronounced than I remember from the early 80's. When I scroll the display, the image persists for much longer than I think is normal -- it takes around 2 seconds to completely decay. Is this...
  5. K

    Serial Connection -- Laptop to IMSAI

    I'm absolutely sure that I will get a dozen replies saying that you have been doing this for years, but in case someone, like me, didn't think of it: I have been using a serial port to connect my IMSAI to a Win98SE laptop. This allows me to capture and send short files (under N*DOS or CP/M)...
  6. K

    How do I create a dummy file entry with a specific length?

    I have an old IMSAI with Northstar disk drives on which I run Northstar DOS 5.x and CP/M 2.2, both in double density. I need to transfer both text and binary files back and forth between the two operating systems. I do this with a "special" diskette, which is formatted as single density to...
  7. K

    Websites Not Accessible

    I noticed today that I was unable to access two valuable resources, namely: http://www.retroarchive.org/ http://www.classiccmp.org/dunfield/ I have visited both these sites within the last week or two. I don't think this is a browser problem, but if someone can access these sites, please...
  8. K

    Some CP/M User's Manual Resources

    I recently was successful in getting Dave Dunfield's NST program running on my IMSAI system with Northstar (hard sector) disk drives. This allows me to upload disk images (N* Dos, CP/M, and UCSD Pascal) and save them to disk. There is no shortage of disk images -- Dave Dunfield's website and...
  9. K

    CP/M 2.2x (Northstar Disk) "NSDD" Program

    Does anyone have any documentation on the CP/M 2.2x program NSDD.COM? When I execute it, I get the following: N*DOS -> CP/M File Transfer (NSDD 01.00) [(c) 1981 Infosoft Systems ] # I assume the # (pound sign character) is a prompt. I tried several response forms, but it didn't like any...
  10. K

    CP/M 2.X and IMSAI CPU-B Conflicts

    I used CP/M 1.4x with my IMSAI/Northstar Disk Drive system back in the day. I decided to bring up CP/M 2.2x on my system today. No big deal I thought -- I already had the CBIOS code from 1.4x, and only needed to make a few changes for additional jump vectors, etc. I typed in the CBIOS routine...
  11. K

    Uploading Disk Images to IMSAI

    I have been working off and on for some time to get Dave Dunfield's NST (Northstar disk image transfer) program working on a laptop which is communicating with my IMSAI via a serial cable. His procedure of "typing in" the I/O stub (hex file transfer) to the micro using the Northstar Monitor...
  12. K

    DOS Utility to degragment HD

    Does anyone know of a DOS program which would perform the equivalent of the current Window's defrag utility? The system with the hard disk is running under DOS 3.3.
  13. K

    INTERLNK/INTERSVR running under DOS 3.3!

    I have an external cabinet with a hard disk (Rodime 33MB) attached to one of my IBM 5150's. I have been wanting to transfer a large quantity of older DOS programs/data from a 486DX2 system (running DOS 6.22) back to the IBM PC which is running under DOS 3.3. I had previously backed up the...
  14. K

    External Hard Drive on IBM 5150

    I have two IBM 5150's -- a 16/64KB MOBO which I bought in the fall of 1981, and a 64/256KB MOBO which I bought at a bargain price 2 years later after my daughter "borrowed" the first PC when she left home to attend college. I used an external hard drive with both systems. My external hard...
  15. K

    Un-Documented 8085 Instructions

    While looking through some of my S-100 manuals today I found a two page photocopy of a Dr. Dobbs article which describes ten undocumented 8085 instructions. My vintage IMSAI PCS-80/30 contained a 8085 processor and I used several of these instructions in some of my programming, especially the...
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