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The Namco NA-1/2 is a machine created by Namco, and this board has some interesting features, and programming that yet to be discovered.
Information

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The normal resolution is 288x224, but due to hardware quirks/bugs, the right edge is expanded 1 pixels eariler, making the games run at effective 287x224. Cosmo Gang the Puzzle and Numan Athletics seems to be aware of this bug and expanded 1 pixel rightwards. No other games use the expected resolution.
Specifications

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RAM
* Main - 512KiB (shared by MCU, C219)
* Tile - 288KiB (gfx + shape combined)
ROM - Up To 10MiB Unbanked (no games use bankswitching)
Resolution - Normally 287x224, but can be expanded to 303x224 (320x240 is not proven in real hardware)
Per-column x scroll and per-column line select

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which is controlled by region $ffe000~$ffefff
Line Select is incorrectly implemented by MAME, which is proven by random X-DAY 2 video.
The MCU

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Also known as Namco C69/C70.
This section contains something that has yet to be discovered.
It can play music, but it does require it's own language, which is yet to be discovered.
It can interact with other peripherals.
Ir fetches current control state, which makes the control (almost) up to date. (it can miss the bus of vblank, so the stale input data can be here)
The CusKey

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This chip makes it cartridge swapping very hard, since each cartridge is tied to each board's cuskey.
This chip's secondary purpose is generating random numbers.
HDMA

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Namco NA-1/2 can do HDMA, which is triggered into IRQ 3.
Bitmap Tiles

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Namco NA-1/2 has 4096 8bpp linear 8x8 tiles, and it's corrosponding shape is 1bpp 8x8 tiles.
X-Day 2 Stuff

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X-DAY 2's board is special one. On Main board, it has expanded EEPROM. On ROM Board, it has 2 date displays and printer, RTC clock. This board does not contain mapper.