vdptest

VDP Tester

This program is designed to test the intricacies and fine details of how the VDP interacts with the CPU, especially in areas of possible interest to emulator authors, and also to MSX/MSX2/MSX2+/TR coders that want to make the most out of the VDP to e.g. squeeze as many transfers as possible in the shortest time.

An important detail is that it's designed to run on MSX machines with synced CPU/VDP clocks, not separate. This makes things hard for a particular VDP, the Toshiba T6950, a chip designed for PAL which needs a 22.168 MHz crystal that is not compatible with the regular CPU timings, and therefore always includes a separate crystal for it. That leaves several Sony machines basically untestable with any degree of reliability.

Currently, the code consists solely of a cycles per frame measurer, as the exact cycle count is the basis for syncing with the CPU, which will be needed by the rest of tests. As it is now, it can't run on a machine with less than 16K RAM. If run on a machine with floppies, the second floppy needs to be disabled by pressing CTRL during boot.

See the Releases page for pre-built binaries. Read USAGE.txt for more information.

The license for this code is the Expat license. See the file LICENSE.txt for details.