Convert Unneeded VRAM Into A Storage Device

Pawel Kot writes "Have you ever thought why does your graphics card has so much memory? Do You think you have not enough RAM or awfully slow swap file? Do you need fast ram-disk or diskless machine? Go for it! Take one of these cheap 128MB graphics cards and enjoy the speed. Michal Schulz wrote a good description on how to take the advantage of not used video card memory."

Comments

Re:What the hell can I do with that?

[Ed Avis]

VRAM can be read and written at the same time - at least on the video card. And it should be possible to use the video hardware to blit around chunks of memory very quickly. I wonder if there are any algorithms (apart from those to manipulate a bitmapped display) which could be specially coded to take advantage of this hardware?

Re:I can't help but think....

[jareds]

Besides...this only applies to X users anyway.

That's not true. You don't need to use X to do this, you just need a video card. In fact, if you're just using the machine in console mode, you may as well use your video memory for swap or something.

Temporary use of VRAM

[The Monster]

Isn't this a bit wasteful?

It would be if you bought the card for the express purpose of using the VRAM that way. When I saw this, I had a flashback. When I was using DOS 5/6, with the then-revolutionary ability to remap memory into Upper Memory Blocks between the ROMs and VRAM, I ran into a problem using that memory.

Most of the drivers and TSRs that I wanted to load in the space originally allocated for monochrome video (a 32K block between B0000 and B7FFF) required more space to load than to run so I came up with the solution of 'borrowing' some VRAM and wrote the Video Hole package to do just that. I used a BIOS call to change the display page from 0 to 6 (for reasons I never quite understood, 7 didn't work on my old Trident 8900) and 'borrowed' 24000 bytes (6 pages of VRAM) from the VRAM to allow a program (say MSCDEX?) to fit in there, then 'recalled' the loan, changing back to page 0. That extra 24K more than took care of the transient portion of a lot of programs that otherwise couldn't use the Video Hole.

I don't know if anyone else ever used the darned thing (nobody ever sent me the $5 shareware fee for doing so) but it got uploaded to a bunch of BBSes and works in the real mode phase of Win95 and 98 - if you have hardware with real mode drivers that don't know how to load low and relocate the resident portion high, it will do the job fine.