Support "proper" address translation
mattgodbolt opened this issue · comments
Lines 245 to 264 in a2cf276
| this.readVideoMem = function () { | |
| if (this.addr & 0x2000) { | |
| // Mode 7 chunky addressing mode if MA13 set. | |
| // Address offset by scanline is ignored. | |
| // On model B only, there's a quirk for reading 0x3c00. | |
| // See: http://www.retrosoftware.co.uk/forum/viewtopic.php?f=73&t=1011 | |
| var memAddr = this.addr & 0x3ff; | |
| if ((this.addr & 0x800) || this.isMaster) { | |
| memAddr |= 0x7c00; | |
| } else { | |
| memAddr |= 0x3c00; | |
| } | |
| return this.cpu.videoRead(memAddr); | |
| } else { | |
| var addr = (this.scanlineCounter & 0x07) | (this.addr << 3); | |
| // Perform screen address wrap around if MA12 set | |
| if (this.addr & 0x1000) addr += this.screenAdd; | |
| return this.cpu.videoRead(addr & 0x7fff); | |
| } | |
| }; |