Uncreative Labs

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

When switching DOS into "unreal" mode, how exactly is memory above 640kb accessible to DOS? Would it be available as "conventional" memory, or through some other proprietary method?

Joined: 22 Apr 2007 Posts: 20

http://en.wikipedia.org/wiki/Unreal_mode

Essentially all of it is available as "conventional" memory.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I would really like to see what happens when you run Windows 3.0 with the /R command in Unreal mode....

Joined: 19 Apr 2006 Posts: 261 Location: WisConSin

I am curious how some machines achieved more than 640kb base memory on 8088 processors, my tandy could be expanded to 768kb of base ram if I installed an expanded memory card, furthermore it said it was useable base ram.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

You can do it on any 8088 computer. There are several different methods to do it, but the easiest way is to install an EMS board. LIM 4.0 works best. The amount of memory from the HMA that you can get back as conventional depends on the number of devices using the HMA. 768k conventional or more is probably possible on a machine without network adapter and graphics card. I haven't had a chance to try it yet, so I can't give you any exact answers at the moment.

The other way to get the UMBs is to install 1MB of RAM into your system, and run a TSR like QRAM or The Last Byte. Using this method, a 640k motherboard is preferable since is supports 256kbit chips and you can put the 1MB RAM on the motherboard. If you have a 256kb motherboard and an AST sixpack plus, you would have to install a second 384k expansionboard.

The third method is the same as the 2nd, except instead of running a TSR, you have to get a custom ROM for your motherboard.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

Oh, and there is actually one more method that also involves a QRAM or similar TSR....

You can actually use the unused DRAM on your EGA or VGA graphics adapter as conventional memory, but it is about six times slower than normal RAM...so it'snot recommended unless absolutely necessary. It's neat to try though.

Joined: 19 Apr 2006 Posts: 261 Location: WisConSin

I always thought that video card memory could only be used as a ram drive when you didn't use a graphics mode, what utilities could use VGA card memory as conventional? I would like to try this on one of my less expandable systems.

Thanx
Ryan

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I am guessing that you could only use the DRAM on your video controller as UMB memory under certain display resolutions. You should download QRAM or Last Byte and give it a shot.

Joined: 19 Apr 2006 Posts: 261 Location: WisConSin

UMBs are OK but conventional sounded much better, I can only move maybe 24k out using that method (ideally anyway)