Demonstrating FLAT memory usage for PB DOS

[Gunther]

We had a small but fair discussion about flat real mode/ unreal mode and the advantages or disadvantages here. For members not familiar with that technique, I've found an old example which I've written for PB 3.2 and TASM 4 in the 90s. The assembly language source could be assembled with MASM or JWASM, too.

It will generate an integer array in the usual DOS memory, save the array above 1 MB, delete the original array and restore it's content. Moreover, it'll draw the Barnsley fern in SCREEN 12 (standard VGA: 640x480 in 16 (!) colors) and save and restore it, just like the integer array.

It will only work under plain DOS with HIMEM.SYS 2 and above or a virtual machine (DOSBox, VirtualBox are tested, but VMWare, Bochs, VirtualPC etc. should do the job, too). It won't work with the DOS emulation of Windows, OS/2 or DOSEmu. There's no chance to bring it to work in these environments. That's what I meant in the above discussion and that's the price which is to pay for the flat mode. Therefore is a clean 32 bit Protected Mode client probably the better way.

Anyway, here it is. This weekend I'll try some VESA stuff with that technique. Have fun and take care.

Gunther

[FORTRANS]

Hi,

   Worked as stated.  Error message in a VDM.  It did what it
said it would do with MS-DOS 6.22 and HIMEM.SYS.  Numbers
and the ferns as stated.

Regards,

Steve N.

[Gunther]

Hi Steve,

   Worked as stated.  Error message in a VDM.  It did what it
said it would do with MS-DOS 6.22 and HIMEM.SYS.  Numbers
and the ferns as stated.

that was clear. Thank you for testing it. In Bochs etc. it'll do the job, too.

Gunther