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Inter-Session Data Passing

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NWR
2018-04-29
2018-04-29
  • NWR

    NWR - 2018-04-29

    Several questions:
    • Is there a “method” for a vDos session to talk to another vDos session?
    • It looks like the environments and video memory and not “shared” in any fashion.
    • It there a method to install a common block (ie. a shared installed program that is just a memory shell)?
    • There used to be “The Intra-Application Communications Area” for this purpose. It was only 16 bytes (0040:00F0h). Does vDos have something like that?
    • Is there a 3rd party “program” to allow program-to-program data passing inside the vDos emulator.
    • You can use a hard drive but it is slow.
    • A ram drive is faster but is not memory-to-memory speed.
    Thanks.
    David

     
    • Jos Schaars

      Jos Schaars - 2018-04-29

      vDos sessions are separate virtual DOS PC’s. They have their own isolated/local environments, video memory, BIOS data area’s and so on. You wouldn’t want those to be shared between sessions, since that would prevent you from running more than one vDos session at the same time.

      DOS programs in different vDos sessions can communicate by reading and writing to shared files. Since they would run on the same physical PC, using the same local drive, speed shouldn’t be an issue due to Windows caching. A second option would probably be to use the Windows Clipboard (device = clip). Another to install a Windows virtual serial port driver with two serial ports cross linked.

      Jos

       
  • Jos Schaars

    Jos Schaars - 2018-04-29

    You probably could exchange Windows environment variables using CMD and ‘refresh’ the linked DOS variables. But that won’t be an effective instrument to exchange (binary) data.

    I had to lookup what “The Intra-Application Communications Area” is supposed to be. It’s of course also in vDos (0040:00F0-00FFh); no gaps in BIOS/DOS memory. But also no magic in real or simulated BIOS. I doubt these 16 bytes are ever used for this purpose. Just some reserved/defined BIOS data because of some unused/undefined space left there…

    Even if used, two PC’s obviously can’t magically share memory, neither can virtual PC’s. And no absolute memory addresses in modern Windows!

    No idea why you need two (virtual) PC’s to exchange data. Certainly if virtual on the same PC, it seems llittle sense since they share the same file system. I doubt you can come with a case where speed would be an actual issue.

    Jos

     
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