trunk/src/devices/bus/a2bus/a2themill.c
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| 7 | 7 | Implementation of the Stellation Two The Mill 6809 card |
| 8 | 8 | |
| 9 | 9 | The OS9 add-on changes the address mapping as follows: |
| 10 | | 6809 0x0000-0xafff -> 6502 0x1000-0xbfff |
| 11 | | 6809 0xb000-0xdfff -> 6502 0xd000-0xffff |
| 12 | | 6809 0xe000-0xefff -> 6502 0xc000-0xcfff |
| 13 | | 6809 0xf000-0xffff -> 6502 0x0000-0x0fff |
| 10 | 6809 0x0000-0x7fff -> 6502 0x1000-0x8fff |
| 11 | 6809 0x8000-0xafff -> 6502 0xd000-0xffff |
| 12 | 6809 0xb000-0xbfff -> 6502 0xc000-0xcfff |
| 13 | 6809 0xc000-0xcfff -> 6502 0x0000-0x0fff |
| 14 | 6809 0xd000-0xffff -> 6502 0x9000-0xbfff |
| 14 | 15 | |
| 15 | | (reference: http://mirrors.apple2.org.za/ground.icaen.uiowa.edu/MiscInfo/Hardware/mill.6809 ) |
| 16 | (reference: "6809.txt" on one of the disks for The Mill) |
| 16 | 17 | |
| 17 | 18 | ProDOS "Stellation The Mill Disk.po" requires Mill in slot 2; boot |
| 18 | 19 | the disc and type "-DEMO1" and press Enter to launch the simple demo. |
| 19 | 20 | |
| 20 | | The OS9 disk image available around the internet seems to be bad - the |
| 21 | | 6809 boot vector is 0x4144 which maps to 6502 0x5144 and there's all |
| 22 | | zeros from 6502 1000-8fff. There is valid 6809 code from 9000-BFFF |
| 23 | | at the point where it wants to boot the 6809, but I don't know what |
| 24 | | is supposed to be the entry point. |
| 21 | TODO: Add DIP switch to select standard and OS-9 modes. |
| 25 | 22 | |
| 26 | 23 | *********************************************************************/ |
| 27 | 24 | |
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| 103 | 100 | { |
| 104 | 101 | m_bEnabled = false; |
| 105 | 102 | m_flipAddrSpace = false; |
| 106 | | m_6809Mode = false; |
| 103 | m_6809Mode = true; |
| 107 | 104 | m_status = 0xc0; // OS9 loader relies on this |
| 108 | 105 | m_6809->set_input_line(INPUT_LINE_HALT, ASSERT_LINE); |
| 109 | 106 | m_6809->set_input_line(INPUT_LINE_RESET, ASSERT_LINE); |
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| 238 | 235 | |
| 239 | 236 | READ8_MEMBER( a2bus_themill_device::dma_r ) |
| 240 | 237 | { |
| 238 | // MAME startup ordering has the 6809 free-running at boot, which is undesirable |
| 239 | if (!m_bEnabled) |
| 240 | { |
| 241 | m_6809->set_input_line(INPUT_LINE_HALT, ASSERT_LINE); |
| 242 | } |
| 243 | |
| 241 | 244 | if (m_6809Mode) |
| 242 | 245 | { |
| 243 | | if (offset <= 0xafff) |
| 246 | if (offset <= 0x7fff) |
| 244 | 247 | { |
| 245 | 248 | return slot_dma_read(space, offset+0x1000); |
| 246 | 249 | } |
| 247 | | else if (offset <= 0xbfff) |
| 250 | else if (offset <= 0xafff) |
| 248 | 251 | { |
| 249 | | return slot_dma_read(space, (offset&0xfff) + 0xd000); |
| 252 | return slot_dma_read(space, (offset&0x3fff) + 0xd000); |
| 250 | 253 | } |
| 251 | | else if (offset <= 0xcfff) |
| 254 | else if (offset <= 0xbfff) |
| 252 | 255 | { |
| 253 | | return slot_dma_read(space, (offset&0xfff) + 0xe000); |
| 256 | return slot_dma_read(space, (offset&0xfff) + 0xc000); |
| 254 | 257 | } |
| 255 | | else if (offset <= 0xdfff) |
| 258 | else if (offset <= 0xcfff) // 6809 Cxxx -> 6502 ZP |
| 256 | 259 | { |
| 257 | | return slot_dma_read(space, (offset&0xfff) + 0xf000); |
| 260 | return slot_dma_read(space, (offset&0xfff)); |
| 258 | 261 | } |
| 259 | | else if (offset <= 0xefff) |
| 262 | else // 6809 Dxxx -> 6502 9000 |
| 260 | 263 | { |
| 261 | | return slot_dma_read(space, (offset&0xfff) + 0xc000); |
| 264 | return slot_dma_read(space, (offset-0xd000)+0x9000); |
| 262 | 265 | } |
| 263 | | else // 6809 Fxxx -> 6502 ZP |
| 264 | | { |
| 265 | | return slot_dma_read(space, offset&0xfff); |
| 266 | | } |
| 267 | 266 | } |
| 268 | 267 | else |
| 269 | 268 | { |
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| 289 | 288 | { |
| 290 | 289 | if (m_6809Mode) |
| 291 | 290 | { |
| 292 | | if (offset <= 0xafff) |
| 291 | if (offset <= 0x7fff) |
| 293 | 292 | { |
| 294 | 293 | slot_dma_write(space, offset+0x1000, data); |
| 295 | 294 | } |
| 295 | else if (offset <= 0xafff) |
| 296 | { |
| 297 | slot_dma_write(space, (offset&0x3fff) + 0xd000, data); |
| 298 | } |
| 296 | 299 | else if (offset <= 0xbfff) |
| 297 | 300 | { |
| 298 | | slot_dma_write(space, (offset&0xfff) + 0xd000, data); |
| 301 | slot_dma_write(space, (offset&0xfff) + 0xc000, data); |
| 299 | 302 | } |
| 300 | 303 | else if (offset <= 0xcfff) |
| 301 | 304 | { |
| 302 | | slot_dma_write(space, (offset&0xfff) + 0xe000, data); |
| 305 | slot_dma_write(space, (offset&0xfff), data); |
| 303 | 306 | } |
| 304 | | else if (offset <= 0xdfff) |
| 307 | else // 6809 Dxxx -> 6502 9000 |
| 305 | 308 | { |
| 306 | | slot_dma_write(space, (offset&0xfff) + 0xf000, data); |
| 309 | slot_dma_write(space, (offset-0xd000)+0x9000, data); |
| 307 | 310 | } |
| 308 | | else if (offset <= 0xefff) |
| 309 | | { |
| 310 | | slot_dma_write(space, (offset&0xfff) + 0xc000, data); |
| 311 | | } |
| 312 | | else // 6809 Fxxx -> 6502 ZP |
| 313 | | { |
| 314 | | slot_dma_write(space, offset&0xfff, data); |
| 315 | | } |
| 316 | 311 | } |
| 317 | 312 | else |
| 318 | 313 | { |