NES 2.0 Mapper 602
NES 2.0 Mapper 602 denotes the Subor SB-2000 UM6576-based educational computer. The first 512 KiB of its PRG address space are PRG-ROM, the second 512 KiB are PRG-DRAM. There are 256 KiB of CHR-RAM, selectable via an outer bank register in 32 KiB amounts.
- First 512 KiB (4 KiB PRG bank# $00-$7F): PRG-ROM
- Second 512 KiB (4 KiB PRG bank# $80-$FF): DRAM
- $4202: Digital Output Register (R)
- $4204: Main Status Register (R)
- $4205: Data Register (R/W)
- $4207: Digital Input Register (R), Configuration Control Register (W)
The floppy disk controller is Intel 82077-compatible.
- $4300: Outer 32 KiB CHR-RAM bank (out of 256 KiB)
- $4301: Reset register: Writing $55 resets the UM6576 to normal NES-compatible mode. Used to run NES games from floppy disk.
- $4302: LPC speech chip, same bit assignents as in mapper 518.