Using file/HDD as memory, XMS, 8086

[Torinde]

Suggestions for features:

• EMS/UMB mapped onto:
  • file (e.g. on (XT-)IDE SSD/RAMdisk)
  • HDD space not managed by DOS
    • another partition
    • unpartitioned area
    • another HDD
    • additional HDD controller, e.g. (XT-)IDE SSD/RAMdisk or similar MFM/ESDI/SCSI
  • PicoMEM/FPGA/etc.
  • emulator host memory
• XMS/HMA mapped onto EMS/UMB/file/etc.
• running on 8086/NEC/etc. (aligned with GLaBIOS/emulator if custom BIOS is needed for something, e.g. HMA/Gate A20 emulation)
• backfilling Conventional memory up to ~1MB (1024K-8K on PC with console redirection, full 1MB on custom hardware/emulator)
• EMS compatibility with 64MB EMS modes of:
  • NEC Vadem VG230
  • C&T F8680A

PC, XT and 24/26-bit 286/386/486 machines will greatly benefit from that.

XMS driver examples:

• AST Research shipped EMS boards with REX.SYS (unclear if applies to PC/XT)
• Intel Inboard 386 (add-on for PC, XT) - utilized DOS drivers to configure the onboard memory.
• PCE emulator - XMS, UMB, HMA on 8086
• XMS, HMA on V30 add-on for Atari ST - Extended memory emulation using the host system capabilities
  -- EXTMEMS.SYS from SOFTBYTE
• 16-bit ISA expansion card that can expand up to 32 MB, EMS, UMB, XMS (286+), 8-bit ISA compatible, PC/XT/AT/386/486 [FEATURE REQUEST] Orchid RAMQuest 8/16 86Box/86Box#4528

Programs mentioning XMS separately from Extended memory:

• Dune 2
• GeoWorks 2
• Space Quest

[Baron-von-Riedesel]

Sorry, I don't understand your features.

PC, XT and 24/26-bit 286/386/486 machines will greatly benefit from that.

Jemm is for 80386+ CPUs only

[Torinde]

Jemm is for 80386+ CPUs only

So, part of the above suggestion is to make it work on 8086 - providing EMS and XMS by using XT-IDE Flash, PicoMEM and the other options mentioned.

[Baron-von-Riedesel]

So, part of the above suggestion is to make it work on 8086 - providing EMS and XMS by using XT-IDE Flash, PicoMEM and the
other options mentioned.

Ok, but Jemm runs in 32-bit protected-mode - there's no feasible way to emulate that on an 80(2)86.

[Torinde]

OK, then just for 386+ CPUs - is it feasible to add the other functions:

• XMS/HMA/UMB/EMS/Conventional backfill - by utilizing space on file/HDD/PicoMEM/RAM card/another memory type (e.g. XMS on file)
• especially for CPUs with 24-bit/26-bit addresses it's relevant to get both additional XMS and EMS somewhere else rather than the limited CPU-attached Extended memory.

[Baron-von-Riedesel]

These all are rather esoteric features - AFAIU it. I can't imagine that anybody takes the effort to implement them.

What's somewhat useful - and I'm afraid that feature isn't even on your list - is to allow the HMA to be included in the range of "mapable" pages for EMS. IIRC that's something the EMS driver for Privateer & Strike Commander does support - but it's pretty much "undocumented", AFAIR.