|
|
| (7 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| [[Category:iNES Mappers]][[Category:MMC3-like mappers]] | | #REDIRECT [[RAMBO-1]] |
| | | {{DEFAULTSORT:064}}[[Category:iNES Mappers]][[Category:MMC3-like mappers]][[Category:in NesCartDB]][[Category:Mappers with scanline IRQs]][[Category:Mappers with cycle IRQs]] |
| See also [[RAMBO-1]]
| |
| | |
| Here are Disch's original notes:
| |
| ========================
| |
| = Mapper 064 =
| |
| ========================
| |
|
| |
|
| |
| aka
| |
| --------------------------
| |
| Tengen RAMBO-1
| |
|
| |
|
| |
|
| |
| Example Games:
| |
| --------------------------
| |
| Klax
| |
| Skull and Crossbones
| |
| Shinobi
| |
|
| |
|
| |
| Notes:
| |
| --------------------------
| |
| This mapper is very similar to MMC3. It uses a similar swapping system, but adds a little functionality.
| |
|
| |
| IRQs are set up similar as well... but have some major differences.
| |
|
| |
| This is one of those mappers that is a big pain to impliment in an emu -- especially since so few games use
| |
| it. And the games that use it really blow hard.
| |
|
| |
|
| |
| Registers:
| |
| --------------------------
| |
|
| |
| Range,Mask: $8000-FFFF, $E001
| |
|
| |
| $8000: [CPK. AAAA]
| |
| C = CHR mode select
| |
| P = PRG mode select
| |
| K = full 1k CHR mode select (see CHR setup)
| |
| A = Address for use with $8001
| |
|
| |
| $8001: [DDDD DDDD] Data port
| |
| R:0 -> CHR reg 0
| |
| R:1 -> CHR reg 1
| |
| R:2 -> CHR reg 2
| |
| R:3 -> CHR reg 3
| |
| R:4 -> CHR reg 4
| |
| R:5 -> CHR reg 5
| |
| R:6 -> PRG reg 0
| |
| R:7 -> PRG reg 1
| |
| R:8 -> CHR reg 6
| |
| R:9 -> CHR reg 7
| |
| R:A - R:E not used
| |
| R:F -> PRG reg 2
| |
|
| |
| $A000: [.... ...M] Mirroring
| |
| 0 = Vert
| |
| 1 = Horz
| |
|
| |
|
| |
|
| |
| $C000: [IIII IIII] IRQ Reload value
| |
| $C001: [.... ...M] IRQ Mode select and reset
| |
| 0 = Scanline (A12) mode
| |
| 1 = Cycle mode
| |
|
| |
| $E000: [.... ....] IRQ Acknowledge/Disable
| |
| $E001: [.... ....] IRQ Enable
| |
|
| |
|
| |
| PRG Setup:
| |
| ---------------------------
| |
|
| |
| PRG mode is selected via $8000.6
| |
|
| |
| $8000 $A000 $C000 $E000
| |
| +-------+-------+-------+-------+
| |
| PRG Mode 0: | R:6 | R:7 | R:F | { -1} |
| |
| +-------+-------+-------+-------+
| |
| PRG Mode 1: | R:F | R:6 | R:7 | { -1} |
| |
| +-------+-------+-------+-------+
| |
|
| |
|
| |
| CHR Setup:
| |
| ---------------------------
| |
|
| |
| $8000 has 2 bits to configure CHR modes. Therefore there are effectively 4 CHR modes.
| |
|
| |
| $8000: [CPK. AAAA] <--- C and K bits relevent to CHR
| |
|
| |
|
| |
| $0000 $0400 $0800 $0C00 $1000 $1400 $1800 $1C00
| |
| +---------------+---------------+-------+-------+-------+-------+
| |
| C=0, K=0 | <R:0> | <R:1> | R:2 | R:3 | R:4 | R:5 |
| |
| +---------------+---------------+-------+-------+-------+-------+
| |
| C=0, K=1 | R:0 | R:8 | R:1 | R:9 | R:2 | R:3 | R:4 | R:5 |
| |
| +-------+-------+-------+-------+---------------+---------------+
| |
| C=1, K=0 | R:2 | R:3 | R:4 | R:5 | <R:0> | <R:1> |
| |
| +-------+-------+-------+-------+---------------+---------------+
| |
| C=1, K=1 | R:2 | R:3 | R:4 | R:5 | R:0 | R:8 | R:1 | R:9 |
| |
| +-------+-------+-------+-------+-------+-------+-------+-------+
| |
|
| |
|
| |
|
| |
| IRQs:
| |
| ---------------------------
| |
|
| |
| There are two seperate IRQ modes. One uses A12 to count scanlines in a manner just like MMC3 does (see
| |
| mapper 004 for details on how scanlines are counted and the restrictions involved). The other mode uses CPU
| |
| cycles with a 4-step prescaler (so the IRQ counter gets clocked every 4 CPU cycles).
| |
|
| |
| Regardless of the mode used to clock the counter... every time the counter is clocked, the following actions
| |
| occur:
| |
|
| |
| - If Reset reg ($C001) was written to after previous clock...
| |
| a) reload IRQ counter with IRQ Reload value **PLUS ONE**
| |
|
| |
| - Otherwise... If IRQ Counter is 0...
| |
| a) reload IRQ counter with IRQ Reload value
| |
|
| |
| - Otherwise...
| |
| a) Decrement IRQ counter by 1
| |
| b) If IRQ counter is now 0 and IRQs are enabled, trigger IRQ
| |
|
| |
|
| |
| Just like with MMC3, the counter is clocked and updated even when IRQs are disabled -- however IRQs will only
| |
| be triggered when enabled.
| |
|
| |
| Note about the plus one: I'm not sure if 1 is really added or if there's simply an additional 1 clock delay
| |
| before the IRQ counter is updated. From a software standpoint, it doesn't really matter -- adding the
| |
| additional 1 works without any side-effects.
| |
|
| |
|
| |
| Registers involved with IRQs:
| |
| ---------------------------
| |
|
| |
| $C000: [IIII IIII] - IRQ Reload value
| |
|
| |
| $C001: [.... ...M] - IRQ Reset reg, mode select
| |
| 0 = Scanline mode (A12)
| |
| 1 = CPU Cycle mode (with prescaler)
| |
|
| |
| Any write to this register will make it so that the IRQ counter will reload with the reload value +1 on
| |
| its next clock. Whether or not writing to this register clears the IRQ counter like it does with MMC3 isn't
| |
| known... and doesn't matter, since it's reloaded later anyway.
| |
|
| |
| Also, any write to this register will reset the CPU cycle prescaler (so that it will be 4 CPU cycles
| |
| until the next clock).
| |
|
| |
| $E000: [.... ....] - IRQ Acknowledge/Disable
| |
| Any write to this register will acknowledge the pending IRQ, and disable IRQs
| |
|
| |
| $E001: [.... ....] - IRQ Enable
| |
| Any write to this register will enable IRQs
| |
|
| |
|
| |
|
| |
| A note about IRQs:
| |
| ------------------
| |
|
| |
| Scanline IRQs seem to trip a little later than they do on the MMC3. It looks like about a 5 dot delay
| |
| from the normal MMC3 IRQ time (265 instead of 260). Failure to put in this delay results in shaking and
| |
| other graphical quirks in some games... notably Klax. This delay also seems to exist for CPU cycle driven
| |
| IRQs (Skull & Crossbones will suffer without it). Perhaps the RAMBO-1's IRQ generating hardware is a little
| |
| slower than usual?
| |
|
| |
| Apart from that timing difference, A12 clocks RAMBO-1's IRQ counter just exactly like it does MMC3, so all
| |
| the notes about A12, $2006/7, etc from the mapper 004 documenation apply to this mapper as well.
| |
