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# 2025-01-05 - FreeDOS Virtual Memory |
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When i tried to view large images on my FreeDOS system with 32 MB of |
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memory, all image viewers ran out of memory and crashed. For this |
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post, i will use DosView 1.7 as the example. |
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DosView 1.7 |
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I chose an image Jason Scott shared of an archivists lair. The image |
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size is 8 MB compressed, and GIMP reports that it takes over 67 MB |
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decompressed. |
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"No, You Have A Problem" |
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When i tried to view this image, i got the following error: |
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C:\DOSVIEW>dosview no-you-have-a-problem.png |
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Can't load image no-you-have-a-problem.png |
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ERROR |
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After i ran "LH CWSDPMI -p -sC:\CWSDPMI.SWP", then DosView churned |
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the disk for a while and displayed the image. |
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C:\DOSVIEW>dosview no-you-have-a-problem.png |
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OK |
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This morning i tried again in a virtual machine and was not able to |
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repeat my success. DosView always failed. This led me to suspect |
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that my configuration was wrong. I searched for DPMI diagnostic |
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information. At first i didn't find much. Finally, i found that |
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DJGPP GDB can report DPMI details. |
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C:\DOSVIEW>copy con sysinfo.gdb |
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set pagination off |
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info dos sysinfo |
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quit |
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^Z |
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When DosView fails, GDB reports the following: |
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C:\DOSVIEW>gdb --command=sysinfo.gdb | find.com "Swap" |
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DPMI Swap Space................0 Bytes |
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When DosView succeeds, GDB reports the following: |
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C:\DOSVIEW>gdb --command=sysinfo.gdb | find.com "Swap" |
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DPMI Swap Space................131072 KB (128 MB) |
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Yesterday, DosView failed using CWSDPMI's default configuration, but |
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succeeded when i loaded it manually. Today it is the opposite. I |
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don't understand why this changed. Now at least i know how to check |
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the DPMI host using DJGPP GDB. |
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tags: bencollver,retrocomputing,technical |
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# Tags |
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bencollver |
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retrocomputing |
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technical |
