This mapper was allocated on 15-nov-2013 to implement some homebrew games, including Glider. FCEUX acquired support on r3029.
The example board in question was marked as follows: "Sealie Computing", "RET-CUFROM revD", "2/29/08"
The board includes 4x banks worth of full 8KB CHR ram, and 8x 16KB PRG banks.
It is hard-wired for vertical mirroring, and contains 8KB of WRAM mounted in the usual place. There is no battery, but pads are present and suitable for such a purpose if anyone were so inclined. There are no bus conflicts.
The board contains logic designed for reprogramming from a CopyNES. If EXP0 and R/W go low, /WR reaches the flash ROM. When EXP0 is high, the internal bankswitching register gets accessed.
Registers:
---------------------------
Range,Mask: $8000-FFFF, $8000
$8000: [...P PPCC]
C = CHR RAM bank
P = PRG ROM bank
PRG Setup:
---------------------------
$8000 $A000 $C000 $E000
+-------------------------------+
| $8000 | { -1} |
+---------------+---------------+
CHR Setup:
---------------------------
$0000 $1000
+-------+-------+
| $8000 |
+-------+-------+
Here's a schematic of the board:
377 O0 --- CRAM A13
377 O1 --- CRAM A14
____
A14 ---------\ \
) >--- ROM A14
377 O2 ------/____/
____
A14 ---------\ \
) >--- ROM A15
377 O3 ------/____/
____
A14 ---------\ \
) >--- ROM A16
377 O4 ------/____/
____
EXP0 --------\ \
) >--- ROM /WE
R/W ---------/____/
,--------------- 377 CLK
|
+--------------- ROM /CE
| ____
/ROMSEL --+--| \
| )--,
M2 ----------|____/ |
,-----------'
| ____
`--| `-.
| \
A14 ---------| )o-- RAM /CE
| /
A13 ---------|____,-'
____
EXP0 --------| `-.
| \
+5V ---------| )o-- 377 /G
| /
,------|____,-'
|
`------------------,
____ |
+5V ------+--| `-. +-- RAM /OE
| | \ |
`--| )o-+-- ROM /OE
| /
R/W ------+--|____,-'
|
`--------------- RAM /WE