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| Bandai EPROM mapper is an ''ad hoc'' designation for a mapper used by Bandai for ''Dragon Ball'' and ''Gundam'' games.
| | #REDIRECT [[Bandai FCG board]] |
| This mapper has two iNES numbers, depending on which save chip is present: [[iNES Mapper 016]] and [[iNES Mapper 159]].
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| Hardware: PRG ROM (16 KiB banks, one switchable and one fixed), CHR ROM (1 KiB banks), no PRG RAM, optional serial EPROM.
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| == Ports ==
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| The mapper's ports are [[mirroring|mirrored]] at $6000-$FFFF, except for the EPROM I/O register which can only be read at $6000-$7FFF.
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| *$8000-$8007: Select 1024 byte CHR bank at $0000, $0400, ..., $1C00
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| *$8008: Select 16384 byte PRG bank at $8000 (the last bank is fixed at $C000)
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| *$8009: Mirroring (0: vertical; 1: horizontal; 2: 1-screen $2000; 3: 1-screen $2C00)
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| *$800A: IRQ control (0: pause; 1: count; any write acknowledges)
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| *$800B: Low 8 bits of IRQ counter
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| *$800C: High 8 bits of IRQ counter
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| *$800D: EPROM write
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| When enabled, IRQ counts down by 1 every CPU cycle. /IRQ goes low when the counter goes from $0001 to $0000, and it goes high when $800A is written.
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| The counter is not reloaded after IRQ; it'll fire once every 65536 cycles unless paused or reloaded with $800B/$800C writes.
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| Any read from $6000-$7FFF appears to read the EPROM.
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| EPROM appears to be laid out like this:
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| <pre>
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| 7 bit 0 $800D: EPROM control
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| |||' ''''
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| ||+-------- Clock?
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| |+--------- Data in?
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| +---------- Unknown
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| 7654 3210 $6000-$7FFF: EPROM read
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| +------ Data out
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| </pre>
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| Some patterns observed in the games' save code:
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| * Start I/O: $00 $40 $60 $20 $00
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| * Write 0 bit: $00 $20 $00
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| * Write 1 bit: $00 $40 $60 $40 $00
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| * Unknown: $00 $20 $A0 Read $00
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| * Read bit: $60 $E0 Read $40
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| * Stop I/O: $00 $20 $60 $40 $C0
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