Functional Description
http://www.motorola.com/computer/literature 3-11
3
ROM/Flash Speeds
The Falcon pair provides the interface for two blocks of ROM/Flash.
Access times to ROM/Flash are programmable for each block. Access
times are also affected by block width. The access times for ROM/Flash
are shown in Table 3-4, Table 3-5, Table 3-6, and Table 3-7.
Table 3-4. PowerPC 60x Bus to ROM/Flash Access Timing when configured
for 180ns Devices
ACCESS TYPE CLOCK PERIODS REQUIRED FOR: Total
Clocks
1st Beat 2nd Beat 3rd Beat 4th Beat
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
4-Beat Read 68 20 64 16 64 16 64 16 260 68
4-Beat Write N/A N/A
1-Beat Read (1 byte) 2020------2020
1-Beat Read (2 to 8
bytes)
6820------6820
1-Beat Write 1919------1919
Table 3-5. PowerPC 60x Bus to ROM/Flash Access Timing when configured
for 120ns Devices
ACCESS TYPE CLOCK PERIODS REQUIRED FOR: Total
Clocks
1st Beat 2nd Beat 3rd Beat 4th Beat
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
16
Bits
64
Bits
4-Beat Read 52 16 48 12 48 12 48 12 196 52
4-Beat Write N/A N/A
1-Beat Read (1 byte) 1616------1616
1-Beat Read (2 to 8
bytes)
5216------5216
1-Beat Write 1919------1919