This board provides:

512K (256K+256K) ROM

2M RAM

By default, when power is first applied or following a hardware reset, the RAM is disabled and the ROM base address is set to 000000h. This is referred to as Mode 0 or BV (Boot Vector) Mode.

The Stack Pointer (SP) will be loaded with the 32-bit address stored in ROM address 000000h and the Program Counter (PC) will be loaded with the 32-bit address stored in ROM address 000004h.

In Mode 1 or RU (RAM Unlocked) Mode the following applies:

The ROM base address is fixed at FC0000h.

The RAM base address is fixed at 000000h.

The transition from Mode 0 to Mode 1 occurs automatically when an address anywhere in the Mode 1 ROM address space (FC0000h - FFFFFFh) is read, this action unlocks (enables) the RAM and relocates the ROM.

BV Mode can be disabled if not required.