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Comment by josmala | Hacker News Reader

Hey that isn't the really impressive, but I did the same thing with DOS configuration files with only using software that came with DOS. I played a game that required 12 megs of RAM and I had 8. I used drivespace to compress the drive and smartdrive to create diskcache. The dos extender of the game automatically swapped to the disk, when there wasn't enough ram. With my set up, the game swapped, then drivespace compressed the data and smartdrive cached the data, and it never hit the disk during a combat anymore and became playable.

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The interesting part is that this thing is for MacOS and apparently mostly works by compressing unreferenced memory segments in RAM.

Contemporary world of various DOS extenders is completely different ball game to the extent that typical DOS extender was more complete operating system implementation than what classic MacOS ever hoped for.

Heh, that is actually pretty clever.

By contrast, I remember people putting swap files (most prominently the Win386 one) into straight RAMDISKs, which should really just give you a net negative effect all across the board.

Unless the ramdisk (AKA tmpfs in modern Linux) is compressed.

Many low footprint Linux installations now include swapping to zram, which is compressed. The net effect is positive since you usually have an abundance of spare CPU cycles.

Well yeah, that was both josmala's (the original commenter) and my point. Putting the swap file in compressed memory (here DriveSpace+SmartDrive) can be good, putting it into a straight, uncompressed ramdisk is worse than useless.

Conversely making your tmp dir a ramdisk was a huge benefit for compilers, because they created lots of temp files in their work.

If I remember correctly, this was usually done because Windows 3.x couldn't handle the full amount of RAM in the system directly for one or other reason. I might be misremembering but I recall some IO cards created a 'hole' by placing memory mapped IO regions somewhere well above 1MB (15M or so?) and Windows couldn't handle non contiguous physical RAM at that point in the address space as an example.

I played Doom like that in win3.11 (which supported disk swapping automatically including for DOS games) on a PC with 4MB RAM while Doom needed 8MB. However, the disk swapping was too slow to make it playable.

Doom only needed 4MB of RAM.

You are right. Correction: The PC had 2MB and doom required 4MB

You should have dumped windows.

I played doom II with 4MB on a 386DX40. We had a DOS 6 boot menu to not load smartdrv. It ran good enough, except on the last level, where all the different enemy types caused all their graphics to be loaded at the same time. That was too much, and caused severe disk trashing (not swapping, DOOM managed the disk on its own).

doom used less memory, so it should have been good enough.

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