Short: A util to change the VBR Author: blacky@caiw.nl Uploader: blacky caiw nl Type: util/misc Requires: 68010+ CPU Architecture: m68k-amigaos VBR displacer for any amiga with a 68010+ CPU. The VBR (Vector Base Register) of the 68010+ CPU'S is used by the CPU to find out where the interrupt-vectors are placed. In the 'old' 68000 the interrupt-vectors were placed at a fixed position, at the start of CHIP-mem. This memory is not always directly available to the CPU (due to DMA activity from the CUSTOM-CHIPS). By using the VBR, these interrupt-vectors can be placed in FAST-mem or 32BIT-mem. There are just two problems with this scheme : 1 - Very many old programs written for the 68000 expect the interrupt vectors to be at the beginning of CHIP-mem. therefor these programs don't work if the VBR is pointing to a different memory-position. 2- The Operating System doesn't alter the VBR (for compatibilty-reasons), but this means that the computer is not running as fast as it can. With this program you can : turn the VBR on - setting it to a point in FAST-mem or 32BIT-mem. turn the VBR off - setting it to the default position for a 68000. #### # # ##### # # # # # # # # # # # # # # # #### # ##### # ### # # # # # # # # # # # #### ##### # # ##### # # # ***** ***** * **** **** * * ***** ***** * * * * * * * * * * * * ***** * ***** **** * * * * ***** * * * * * * * * * * * * * ***** * * * * * **** ***** ***** *