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First post, by fsmith2003

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I am confusing myself when it comes to DOS memory management. In DOS 5.0 when I run mem /c it will tell me I have 0 bytes of contiguous extended memory available. I have 8gb of RAM installed in the computer though. Is this normal or am I missing something to access the memory?

EDIT: I should add that both himem and emm386 are loaded.

Reply 3 of 18, by yawetaG

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It's fairly likely that DOS 5.0 and its utilities don't like that amount of memory at all (hence the "0" bytes free). Use Dosbox and limit the amount of available RAM.

Reply 4 of 18, by squiggly

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fsmith2003 wrote:

I am confusing myself when it comes to DOS memory management. In DOS 5.0 when I run mem /c it will tell me I have 0 bytes of contiguous extended memory available. I have 8gb of RAM installed in the computer though. Is this normal or am I missing something to access the memory?

EDIT: I should add that both himem and emm386 are loaded.

Use HIMEMX and the /max parameter that limits the amount of XMS that DOS can see. 8GB will probably confuse it.

Reply 5 of 18, by dionb

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yawetaG wrote:

8 Gb of RAM and DOS 5.0? Typo?

8Gb? I think he means 8GB - more typo 😉
not that 8Gb=1GB would be any less overkill

But yes, limit with HIMEM.SYS, and limit it hard. It's a rare DOS program that uses more than 8MB, or 1/1024 of what you have. I've already seen flaky behavior in programs with >128MB active, so I'd recommend limiting to 16MB unless you're doing something incredibly exotic.

Note that any system with 8GB of RAM will be running vastly faster than any normal DOS system so that's likely to screw things up as well. If you really don't have anything older, DOSbox is almost certainly a better idea than native DOS on such a system.

Reply 6 of 18, by squiggly

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dionb wrote:
yawetaG wrote:

8 Gb of RAM and DOS 5.0? Typo?

8Gb? I think he means 8GB - more typo 😉

Well to be super-duper-technical it would be 8GiB. Now I want to kill myself for bringing that up.

Reply 7 of 18, by dionb

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squiggly wrote:

[...]

Well to be super-duper-technical it would be 8GiB. Now I want to kill myself for bringing that up.

Which I suppose could then be expressed as 2^14 nibbles - which is fitting as I'm more than a bit peckish at present 😉

Reply 8 of 18, by fsmith2003

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WOW! I'm sorry. I did mean to say 8MB not GB. Just a brain fart on my part I guess. SO knowing that and the fact that im showing no contiguous extended do the tips provided earlier still apply?

Reply 9 of 18, by squiggly

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fsmith2003 wrote:

WOW! I'm sorry. I did mean to say 8MB not GB. Just a brain fart on my part I guess. SO knowing that and the fact that im showing no contiguous extended do the tips provided earlier still apply?

Does BIOS see/test 8MB of ram on startup? How many slots/SIMMS do you have installed to get 8MB?

Reply 10 of 18, by fsmith2003

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Yes it shows up just fine on the memory test. It shows the correct amount of extended memory present but then it just shows that 0 bytes of it are available when the mem command is run in DOS.

Reply 12 of 18, by fsmith2003

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derSammler wrote:

Show us your config.sys and the actual output of mem.

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Reply 13 of 18, by Jo22

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fsmith2003 wrote:

I am confusing myself when it comes to DOS memory management. In DOS 5.0 when I run mem /c it [..]

Wait a minute, didn't DOS 5 come with an ancient version of Himem.sys/EMM386 (v2.77, v4.20.06x)?
It could be well possible that each of it has several other flaws, as well.

Edit: Himem.sys v3.07 has a release date of 02/14/92 and was part of Windows 3.10.
If that's too new, maybe there once where slighlty older versions from the late 1991 (v3.0 to v3.06)..
Perhaps they are still somewhere on the web (MS knowledge base, BBSes, etc.).

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Reply 14 of 18, by derSammler

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That MEM outputs looks fine to me. The sum of free lower memory, XMS, and EMS adds up to almost 8 mb, which is how much memory you have.

That line saying "0 bytes available contiguous extended memory" seems to be normal. If you google for screenshots, you'll find that even the DOS box in Windows XP shows that:

DOS-commands-010.jpg?w=620&q=55&auto=format&usm=12&fit=max&s=e660b13456e49eb12be1e3df6e7d700c

I guess you don't have contiguous extended memory unless the CPU is running in 386 protected mode.

Reply 15 of 18, by tayyare

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I believe it's normal. Just checked from the net and this the first page that comes up:

https://www.computerhope.com/memhlp.htm

Look at the given example mem outputs on the page.

It seems like you have 1Mb of EMS and remainig 6MB as XMS, adding 1MB of lower memory adds up to 8MB and this should be ok I guess. Is there anything wrong with any kind sofware? Any error reports from any programs you run about "not enough xxx memory" ? If not, probably this is the normal situation.

Just an idea, I always use "NOEMS" or "AUTO" parameters instead of "RAM" with EMM386.EXE. Could you please try that? (remove "1024", too).

To say the truth, I'm amazed I never took notice of this before. I'll check my DOS (6.22 and 7.1) rigs tonight and return back to you.

GA-6VTXE PIII 1.4+512MB
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Reply 16 of 18, by derSammler

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tayyare wrote:

I'll check my DOS (6.22 and 7.1) rigs tonight and return back to you.

The MEM command after MS-DOS 5.0 will no longer show that line, as the output is completely different.

Reply 17 of 18, by fsmith2003

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tayyare wrote:
I believe it's normal. Just checked from the net and this the first page that comes up: […]
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I believe it's normal. Just checked from the net and this the first page that comes up:

https://www.computerhope.com/memhlp.htm

Look at the given example mem outputs on the page.

It seems like you have 1Mb of EMS and remainig 6MB as XMS, adding 1MB of lower memory adds up to 8MB and this should be ok I guess. Is there anything wrong with any kind sofware? Any error reports from any programs you run about "not enough xxx memory" ? If not, probably this is the normal situation.

Just an idea, I always use "NOEMS" or "AUTO" parameters instead of "RAM" with EMM386.EXE. Could you please try that? (remove "1024", too).

To say the truth, I'm amazed I never took notice of this before. I'll check my DOS (6.22 and 7.1) rigs tonight and return back to you.

I will try that later. I do believe I may have before and when I leave out the 1024 I was having programs unable to detect any expanded memory.

Reply 18 of 18, by Jo22

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derSammler wrote:

That MEM outputs looks fine to me. [..]
That line saying "0 bytes available contiguous extended memory" seems to be normal.

I belive you're right. The zero amount of memory could be related to the old INT15h interface.
If I tell Himem.sys to reserve 1024KiB of Extendend Memory (not XMS) it will show a number.

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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