668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 55

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

5.3.2 8-bit Operation
On startup Memory Bank 0 is enabled to use /CS0, /OE0, and /WE0 with four wait states
and write protection enabled; it is expected that an external flash device containing startup
code be attached to those strobes. The other memory banks come up undefined and should
be set via the appropriate MBxCR register to a valid setting before use.
The size of the memory banks can be defined in the MECR register. The default size is
256 KB (the bank selection looks at address bits 18 and 19), but this value can be adjusted
down to 128 KB or up to 4 MB per bank.
The two address bits used to select the bank can be inverted in MBxCR, which enables
mapping different sections of a memory device larger than the current memory bank into
memory. An example of this feature is shown in Figure 5-4.
Figure 5-4. Mapping Different Sections of a Memory Device
Larger Than the Current Memory Bank
Chapter 5 Memory Management
45