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sega genesis / mega drive 68000 memory map calculator · rom · z80 · vdp · io registers · work ram · file offset lookup · runs locally

address input

memory map reference

$000000
$3FFFFF

Cartridge ROMMain ROM area (up to 4 MB)

ROM ≡ offset

$400000
$7FFFFF

Cartridge ExpansionBank-switched ROM expansion area (used by larger cartridges via SSF2 or similar mappers)

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$800000
$9FFFFF

Sega CD / 32XMega-CD word RAM / DRAM, 32X frame buffer, or expansion hardware

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$A00000
$A0FFFF

Z80 Address SpaceThe 68000 can access the Z80's 64 KB address space here while holding the Z80 bus

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$A10000
$A1001F

I/O RegistersHardware version, controller ports (1–3), and serial communication control registers

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$A11000
$A110FF

Memory ControlMemory mode register ($A11000), Z80 BUSREQ ($A11100), Z80 RESET ($A11200)

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$A12000
$A14FFF

32X / Expansion32X control registers or Sega CD communication area

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$C00000
$C0001F

VDP Registers & PortsVDP data port ($C00000/$C00002), control port ($C00004/$C00006), H/V counter ($C00008), PSG sound ($C00010), debug reg ($C0001C)

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$E00000
$FFFFFF

Work RAM (mirror)The 64 KB of Work RAM ($FF0000–$FFFFFF) is mirrored throughout this range

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click any row to jump to that region

key i/o registers

$A10000Version Register (hardware version, region, model)

$A10002Controller Port 1 — Data

$A10004Controller Port 2 — Data

$A10006Controller Port 3 (EXT) — Data

$A10008Controller Port 1 — Control (CTRL)

$A1000AController Port 2 — Control

$A1000CController Port 3 — Control

$A1000EController Port 1 — Tx Serial Data

$A10010Controller Port 1 — Rx Serial Data

$A10012Controller Port 1 — Serial Control

$A10014Controller Port 2 — Tx Serial Data

$A10018Controller Port 3 — Tx Serial Data

$A11000Memory Mode Register (DRAM refresh)

$A11100Z80 BUSREQ (write $0100 to request, $0000 to release)

$A11200Z80 RESET (write $0100 to reset, $0000 to clear)

$C00000VDP Data Port (read/write VRAM/CRAM/VSRAM data)

$C00002VDP Data Port (byte mirror)

$C00004VDP Control Port / Status Register

$C00006VDP Control Port (byte mirror)

$C00008H Counter (bits 15–8) / V Counter (bits 7–0)

$C00010PSG Sound (SN76489) — write-only

$C00012PSG Sound (mirror)

$C00014PSG Sound (mirror)

$C00016PSG Sound (mirror)

click any row to load address