In the emulator

The drawings on this site come from the ROM, not from the emulator. But looking at a picture is not enough to believe it: in this series the VRAM is dumped from openMSX and compared byte for byte against what the Python builds. If they match, the format has been read correctly.

For this cartridge 30 screens were dumped — the title, the menu and the nine holes — and the comparison covers 385,199 bytes: patterns and colours of both screens, the sprite patterns, the hole's plan view, its whole header and the eight VDP registers. It comes out at zero differences. The command that does it is

python tools/graficos.py --comprueba golf.rom 0x4000 work/omsx

and the only cell it had to be handed is the wind, which is not in the ROM: ld a,r draws it, so each dump's own values are fed in.

Loading it

openmsx -machine Philips_VG_8020 -cart golf.rom

The measuring scripts

tools/ holds openMSX TCL scripts meant for checking, not for illustrating: they dump the 16 KB of VRAM and the VDP registers and exit on their own, with a real-time watchdog so a broken script cannot leave the emulator hanging.

Two things learned the hard way, in case you write your own: in TCL do not nest quotes inside a string (use {VDP regs}), and do not set breakpoints that fire every frame inside drawing routines — they choke the emulator, which then never even gets a game started.