NINA-001

Board

Tech Specs:

Max. 64K PRG ROM.
Max. 64K CHR ROM.
8K WRAM.
74LS133
74LS74
74HCT139
74LS00
74HCT173 (2)
17677 NINA lockout replacement

Description:

This seems to be the first game SEI Released, and then AVE re-relased. It is the board from Impossible Mission 2, which has 3 different cart cases that I know of. One's marked 'SEI' and has a colour label, another is also marked 'SEI' but is just a black and white text label, and the third if the AVE release. All three use an identical PCB and contain identical code. There's what appears to be a pre-programmed microcontroller on the board running to a cap and then to one of the lockout chip pins... most likely it just feeds these pulses to the chip to disable it.

This cart maps 3 registers in at 7FFDh through 7FFFh.  7FFCh is decoded, but not used.

7FFDh:
------

7       0
---------
xxxx xxxP

P:
Select a 32K PRG page.


7FFEh:
------

7       0
---------
xxxx CCCC

C:
Select a 4K CHR page at 0000-0FFFh in PPU space


7FFFh:
------

7       0
---------
xxxx CCCC

C:
Select a 4K CHR page at 1000-1FFFh in PPU space


Cart has 8K of WRAM mapped in at 6000-7FFFh.  Bank values are unknown on startup.  Mirroring
is hardwired.