DOS ain't dead

giving back a block of HMA (Announce)

posted by Ninho , 10.06.2010, 16:03

> There would be few risks unloading UIDE, as it "hooks" only the Int 13h
> vector and can easily "give back" its XMS and upper memory. The problem
> is that most users load it in the HMA, and I am not sure if HMA space can
> be "given back".

Not in MSDOS 5/6, but yes in MSDOS 7+ it is easy enough to free a block of HMA (that you "own"!) and give it back to DOS - each allocated block is preceded by a control block (similar to an MCB, let's call them HMCBs). There is no API for giving the block back,[°edit : or maybe there is one, I don't recall and can't check now but it doesn't matter as...] we can achieve that by direct HMCB editing... However that will leave a hole in the HMA which probably won't be reused anyway, there is no way to move system blocks around and defragment the HMA ;)

As for FreeDOS and others, I have no idea how they manage allocation from the HMA. Oh, I seem to remember DRDOS 6 had a working scheme, much in advance of MS-DOS (of course...)

---
Ninho

Complete thread:

• "That Will Be ALL!" For UIDE and USB! - Jack, 06.06.2010, 20:37
  • "That Will Be ALL!" For UIDE and USB! - Rugxulo, 07.06.2010, 04:20
    • Re: UIDE Unloading And Cache-Sizes. - Jack, 07.06.2010, 05:30
      • Re: UIDE Unloading And Cache-Sizes. - Rugxulo, 08.06.2010, 01:35
        • Re: UIDE Unloading And Cache-Sizes. - marcov, 08.06.2010, 23:18
          • Re: UIDE Unloading And Cache-Sizes. - Rugxulo, 09.06.2010, 04:23
  • "That Will Be ALL!" For UIDE and USB! - Japheth, 07.06.2010, 07:51
  • TSR vs DEVICE= - DOS386, 07.06.2010, 08:01
    • TSR vs DEVICE= - RayeR, 08.06.2010, 15:46
      • TSR vs DEVICE= - Arjay, 08.06.2010, 19:30
        • TSR vs DEVICE= - RayeR, 09.06.2010, 02:00
        • TSR vs DEVICE= - Japheth, 09.06.2010, 09:50
          • TSR vs DEVICE= - RayeR, 09.06.2010, 16:15
        • TSR vs DEVICE= - roytam, 09.06.2010, 18:18
      • TSR vs DEVICE= - DOS386, 27.06.2010, 14:30
    • TSR vs DEVICE= - bretjohn, 18.06.2010, 21:50
      • TSR vs DEVICE= - Jack, 18.06.2010, 23:29
        • TSR vs DEVICE= - bretjohn, 19.06.2010, 01:18
        • Nothing Against You! - Jack, 19.06.2010, 01:52
      • TSR vs DEVICE= - Japheth, 19.06.2010, 09:02
        • TSR vs DEVICE= - Arjay, 19.06.2010, 19:13
        • TSR vs DEVICE= - bretjohn, 19.06.2010, 20:33
          • TSR vs DEVICE= - Japheth, 20.06.2010, 09:04
            • TSR vs DEVICE= - Arjay, 20.06.2010, 12:48
            • TSR vs DEVICE= - bretjohn, 20.06.2010, 16:32
              • TSR vs DEVICE= - Ninho, 20.06.2010, 17:34
  • "That Will Be ALL!" For UIDE and USB! - marcov, 08.06.2010, 22:41
    • "Capital Letters". - Jack, 08.06.2010, 23:15
      • "Capital Letters". - marcov, 08.06.2010, 23:19
        • No "Rants", But ... - Jack, 09.06.2010, 00:24
        • "Capital Letters". - Arjay, 09.06.2010, 00:37
          • "Capital Letters". - Jack, 09.06.2010, 00:48
            • Seeking the middle ground: thinking re flexibility+realibity - Arjay, 09.06.2010, 02:29
              • Bret's USB driver bugs - I was testing v0.11 by accident - Arjay, 09.06.2010, 02:50
              • Seeking the middle ground ... - Jack, 09.06.2010, 04:29
                • giving back a block of HMA - Ninho, 10.06.2010, 16:03
                  • Giving Back HMA ... - Jack, 10.06.2010, 17:03
                    • Giving Back HMA ... - Ninho, 11.06.2010, 09:48
                      • Giving Back HMA ... - Jack, 11.06.2010, 16:43
                        • Giving Back HMA ... - Ninho, 12.06.2010, 20:30
                • Seeking the middle ground ... - Arjay, 11.06.2010, 19:29
                  • Seeking the middle ground ... - Jack, 11.06.2010, 21:42
                    • Seeking the middle ground ... - Arjay, 12.06.2010, 01:12
                      • Combined .com executable/DOS driver - Ninho, 12.06.2010, 14:37
                        • Combined .com executable/DOS driver - Arjay, 12.06.2010, 15:13
                          • Combined .com executable/DOS driver - Ninho, 12.06.2010, 15:49
                            • Combined .com executable/DOS driver - Arjay, 12.06.2010, 16:33
                              • Combined .com executable/DOS driver - RayeR, 13.06.2010, 10:41
                                • Combined .com executable/DOS driver - Arjay, 13.06.2010, 16:11
                              • Combined .com executable/DOS driver - Ninho, 13.06.2010, 13:24
                                • Combined .com executable/DOS driver - Arjay, 13.06.2010, 18:54
                          • Combined .com executable/DOS driver - Arjay, 13.06.2010, 20:42
                            • Combined .com executable/DOS driver - Rugxulo, 14.06.2010, 04:27
                              • Combined .com executable/DOS driver / RJDUMP - Arjay, 19.06.2010, 15:08
                            • Combined .com executable/DOS driver - Matjaz, 20.06.2010, 11:58
                              • Combined .com executable/DOS driver - Turbo pascal example - Arjay, 20.06.2010, 13:06
                                • Combined .com executable/DOS driver - Turbo pascal example - Arjay, 20.06.2010, 13:39
                        • Combined SYS device drivers - more than 1 driver in a file - Arjay, 21.06.2010, 17:48
                        • Combined .com executable/DOS driver, multi-header drivers - ecm, 10.08.2010, 18:49
                          • Combined .com executable/DOS driver, multi-header drivers - Arjay, 10.08.2010, 19:41
                            • Combined .com executable/DOS driver, multi-header drivers - ecm, 10.08.2010, 20:21
  • No "Removable" HARD Disks Supported By UIDE! - Jack, 08.06.2010, 23:57
  • "That Will Be ALL!" For UIDE and USB! - bretjohn, 15.06.2010, 22:47
    • Further Comments ... - Jack, 16.06.2010, 01:35
    • "That Will Be ALL!" For UIDE and USB! - Rugxulo, 17.06.2010, 12:07
      • "That Will Be ALL!" For UIDE and USB! - bretjohn, 17.06.2010, 16:53
        • "That Will Be ALL!" For UIDE and USB! - Rugxulo, 17.06.2010, 17:45