That doesn't quite tell everything I need. Try running svgainifo.
The stuff returned for mode 256 is: SVGAINFO Version 1.1 by Ron Thomas Copyright 1994 Video mode in decimal:256 Vesa Signature: VESA Vesa Version: 3.0 BIOS Identification: NVidia Capabilities: 01000000 Number of killobytes of Video memory:4096 Supported VESA modes:- 256 257 258 259 260 261 262 263 264 265 266 267 268 270 271 273 274 276 277 279 280 282 304 305 306 307 308 309 310 317 318 325 326 Press Enter for more info Information for mode:256 Mode_Attributes: 039F Window A attributes: 07 Window B attributes: 00 Window granularity in kb: 64 Window size in kb: 64 Window A start segment: A000 Window B start segment: 0000 WinFunc Pointer: C000:5B6F Bytes per scan line: 640 Horizontal resolution: 640 Vertical resolution: 400 Character cell width: 8 Character cell height: 16 Number of memory planes: 1 Bits per pixel: 8 Maximum number of colours: 256 Number of banks: 1 Memory model type: 4:- Packed pixel graphics Bank size in kb: 0 Number of image pages: 15 Press Enter for more info 4F06h, Set/Get Logical Scan Line Length function, is Not supported 4F07h, Set/Get Logical Display Start function, Is supported 4F08h, Set/Get DAC Palette Control function, Is supported 4F09h, Set/Get Palette Data function, is Not supported 4F0Ah, Return VBE Protected Mode Interface function, Is supported 4F0Bh, Set/Get Pixel Clock function, Is supported 4F4Dh, Video Cursor Interface Request function, is Not supported 4F12h, Display Management Power Signaling function, Is supported