Open Hardware BBC RAM/ROM Board
My current thoughts are a board that covers the BBCs 4 sideways ROM sockets and has the following features: 1 4 MBit (512KB) 32 Pin DIP Flash Chip (Socketed) [Microchip Technology SST39SF040-70-4C-PHE] 1 4 Mbit (512KB) SRAM Chip [Alliance Memory, Inc. AS6C4008-55PCN] 1 PLD to handle the logic [ATF1502ASL-25JU44-ND] 1 Simple diode battery backup circuit and battery connector or maybe an IC [DS1210S+TRL-ND] for Battery Backup.
Slot 15 will contain the ROM Manager. 8 Slots will be Write Protected RAM. 8 Slots will be Read Write RAM. 16 pages of Flash will be selected at power on with the ability to switch to 16 pages of RAM after boot.