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Swap Disk full, to little memory?

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mattisengstedt

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Jul 10, 2024
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I tried running a program on MS DOS but during init it complained that the Swap Disk is full and the entire system basically shut down. I´m guessing this is due to me only having 1MB of memory installed?
 
What kind of program?
What does it say exactly?
Which dos version?
What’s your system?
What do you mean by “shut down”?
 
Maikudou said:
What kind of program?
What does it say exactly?
Which dos version?
What’s your system?
What do you mean by “shut down”?
Click to expand...
ADOM, a game. Happened during creation of the game world.
"Swap Disk Full!"
MS DOS 6.22
Compaq Portable 386 1MB memory
I got an error text and the computer was unresponsive, something about failing to load COMMAND and something about the system.
 
The specs do not mention minimum reqs for DOS, but given it requires 4MB on Amiga might indicate 1MB is not enough
www.mobygames.com

Ancient Domains of Mystery Attributes, Tech Specs, Ratings - MobyGames

Ancient Domains of Mystery attributes, tech specs, ratings
www.mobygames.com www.mobygames.com

The error does not clearly mention RAM though, it seems to have tried to swap some data to disk, and probably does something wrong while trying it, unloading command.com maybe? We'll need a more knowledgable folks to chime in.

Check if notes about DOS quirks on MobyGames help you in any way (it says its from game readme file).

Do you have any memory managers running? In my understanding to access more tham 640Kb dos does need some.
 
The game uses CWSDPMI which suggests it would need a good amount of extended memory. I don't exactly understand why the documentation fails to list minimal requirements in an obvious place.

Is the game a clean install or copied from somewhere else? Copied installs may have settings that point to disks that don't exist.
 
krebizfan said:
The game uses CWSDPMI which suggests it would need a good amount of extended memory. I don't exactly understand why the documentation fails to list minimal requirements in an obvious place.

Is the game a clean install or copied from somewhere else? Copied installs may have settings that point to disks that don't exist.
Click to expand...

Guessing the continued support for MS DOS is more of a fun gimmick so they don´t take the requirements that seriously. The game is about 4-5 MB and the executable is 3.6 with no floppy image version which I had thoughts about.

It´s a clean install.
1. Downloaded from site
2. Used ARJ in Dosbox to compress and split
3. Transfered to my 386
4. Unpacked everything

It starts and I get the intro, but then it fails while loading the game world. Going to give it a few more tries tomorrow just to see if I can sort it out.

Maikudou said:
The specs do not mention minimum reqs for DOS, but given it requires 4MB on Amiga might indicate 1MB is not enough
www.mobygames.com

Ancient Domains of Mystery Attributes, Tech Specs, Ratings - MobyGames

Ancient Domains of Mystery attributes, tech specs, ratings
www.mobygames.com www.mobygames.com

The error does not clearly mention RAM though, it seems to have tried to swap some data to disk, and probably does something wrong while trying it, unloading command.com maybe? We'll need a more knowledgable folks to chime in.

Check if notes about DOS quirks on MobyGames help you in any way (it says its from game readme file).

Do you have any memory managers running? In my understanding to access more tham 640Kb dos does need some.
Click to expand...

Going to have to read up on memory managers. Familys first PC growing up was a 486 with Windows 3.1 and my first personal had Windows 98, so MS DOS and everything from that era is new to me.
 
CWSDPMI supports using a swapfile (which is somewhat unusual for DOS applications). I remember running CWSDPMI with the name of a swap file specified on the command line and being able to run some emulator that needed way more than the 8MB of RAM I had at the time. I don't know if it works with only 1MB. If it does, the performance might be pretty bad because of all the paging. Your game likely has an old version of CWSDPMI, whereas if you check online you should be able to find the last version (dated 2000) which will also include documentation ie. CWSDPMI.DOC

The "cannot load COMMAND.COM, system halted" message generally indicates that conventional memory has been trashed by wayward code in my experience. Under normal circumstances, if DOS can't load COMMAND.COM for some reason it will ask you to enter the path rather than halting.
 
bakemono said:
CWSDPMI supports using a swapfile (which is somewhat unusual for DOS applications). I remember running CWSDPMI with the name of a swap file specified on the command line and being able to run some emulator that needed way more than the 8MB of RAM I had at the time. I don't know if it works with only 1MB. If it does, the performance might be pretty bad because of all the paging. Your game likely has an old version of CWSDPMI, whereas if you check online you should be able to find the last version (dated 2000) which will also include documentation ie. CWSDPMI.DOC

The "cannot load COMMAND.COM, system halted" message generally indicates that conventional memory has been trashed by wayward code in my experience. Under normal circumstances, if DOS can't load COMMAND.COM for some reason it will ask you to enter the path rather than halting.
Click to expand...
Found the docs and the error message I got.

"'Swap disk full!'

This means the paging file could not be expanded when trying to page
memory out to disk. This would normally not be seen, unless you are
writing output to the same disk which holds the paging file. Decrease
the amount of memory your DPMI application is using or free up disk space."

Gonna take a look at the swap file and see if I can do something about it.
 
COMMAND.COM consists of 2 parts, one permanent and one temporary. If the system is running out of memory the temporary part can be unloaded and the memory used by it given over to the process that needs it.

When the process is finished, then the temporary part gets reloaded back from disk, by using the COMSPEC variable to know where to find it.
If it can't be found, then you'll get the message "cannot load COMMAND.COM, system halted".
 
Last night I took it apart to inspect the speaker, today it can't find the HDD anymore, a CF card.

Gonna take a break, water my tomatoes and touch some grass.
 
mattisengstedt said:
Found the docs and the error message I got.

"'Swap disk full!'

This means the paging file could not be expanded when trying to page
memory out to disk. This would normally not be seen, unless you are
writing output to the same disk which holds the paging file. Decrease
the amount of memory your DPMI application is using or free up disk space."

Gonna take a look at the swap file and see if I can do something about it.
Click to expand...
mattisengstedt said:
Last night I took it apart to inspect the speaker, today it can't find the HDD anymore, a CF card.

Gonna take a break, water my tomatoes and touch some grass.
Click to expand...

Wait... did I just discover the reason for my error? I never started up again after the error. Could that have been the moment the CF card broke down and thus generate that error? Cant find COMMAND.COM if there is no HDD.

Tested the CF card on another PC and it was dead. Tried a real IDE HDD on the 386 and it discovered it fine, currently installing DOS 6.22 on it. Will try the game again and report back.
 
DOS and early versions of Windows are really hard on flash memory because of how often they read and write from disk. Not really surprising the CF card died. If it didn't have wear leveling built into the card, it'd get worn out real quick.
 
I wouldn't say dos writes too much if at all, unless a program uses paging like in this very uncommon case.
 
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