20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 51

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

5. M
M
EMORY
ANAGEMENT
5.1 Overview
The Rabbit 4000 supports both 8-bit and 16-bit external flash and SRAM devices; three
chip selects and two read/write-enable strobes allow up to six external devices to be
attached at once. The 8-bit mode allows 0, 1, 2, or 4 wait states to be specified for each
device, and the 16-bit mode allows 0 to 9 wait states depending on the settings. Both 8-bit
and 16-bit page-mode devices are also supported.
The Rabbit 4000’s physical memory space contains four consecutive banks, each of which
can be mapped to an individual chip-select/enable strobe pair. The banks can be set for
equal sizes ranging from 128KB up to 4MB, providing a total physical memory range from
512KB up to 16MB. Figure 5-1 shows a sample configuration.
Figure 5-1. Mapping Rabbit 4000 Physical Memory Space
Chapter 5 Memory Management
41