A first-generation MSX: the TMS9918 VDP in SCREEN 2, the PSG and the SCC the cartridge carries itself. The VDP registers come from the table at p00:5D1D: names at 0x3800, colours at 0x0000, patterns at 0x2000, sprite attributes at 0x3B00 and their patterns at 0x1800.
It is Konami's with SCC: sixteen 8 KB banks. Bank 0 is fixed at 0x4000 and the other three slots are chosen by writing to 0x7000, 0x9000 and 0xB000 (p00:4108-p00:415D). The game keeps a copy of each in 0xF0F1-0xF0F3, and the interrupt puts them back from there (p00:4050). Writing 0x3F to 0x9000 brings up the SCC registers at 0x9800 (p04:71D3).
INIT (p00:4090) installs the H.KEYI hook and stays in jr $: the whole game runs inside the interrupt (p00:4023). First comes the sound, with banks 4-5-6 (p04:6934). Then, if the previous frame has finished (0xE1C5), a game frame starts: the previous frame's screen goes to the VRAM (p00:5D2A) and then the game state runs (p00:5601).
It lives in bank 4. There are 8 channels of 40 bytes from 0xE000: 3 for the PSG and 5 for the SCC. There are 67 sounds, each with its header of channels and priority (p04:6612); a score only takes a channel if its priority is not lower than the one playing (p04:655D). Scores have 31 commands (p04:6D27) and the SCC uses its own waveforms (p04:6000). In the pause, sound 0xF3 saves the channels and 0xF2 puts them back (p04:65DE, p04:65A1).
The game uses 0xE000-0xEFFF, which INIT clears. The 12 enemies are 64-byte records at 0xE600, the 10 bullets are at 0xE900 and the ship's 9 shots at 0xE470. The screen is built in RAM, at 0xED00, and copied whole to the VRAM every frame (p01:77F1). The sprites are ordered at 0xE280 and each frame starts from a different one (p01:77B6), so they flicker instead of vanishing.