Jameco Electronics 2000, 3000 manual Example

Models: 3000 2000

1 349
Download 349 pages 5.72 Kb
Page 229
Image 229
Example

Figure 16-4illustrates the sources that create memory access time delays.

clock period shortening Manual background due to spectrum spreader

clock

address

clock to Manual background address output

data out

Manual backgroundManual background memory accessManual backgroundManual background time

data in setup time

output enable (early)

Manual backgroundManual background memory output enable time

Figure 16-4. Sources of Memory Access Time Delays

The gross memory access time is 2T, where T is the clock period. To calculate the actual memory access time, subtract the clock to address output time, the data in setup time, and the clock period shortening due to the clock spectrum spreader from 2T.

Example

clock = 29.49 MHz,

T = 34 ns,

operating voltage is 3.3 V,

bus loading is 60 pF,

address to output time = 8 ns (see Table 16-2),

data setup time = 1 ns,

the spectrum spreader is on in normal mode, resulting in a loss of 3 ns. The access time is given by

access time = 2T - (clock to address) - (data setup) - (spreader delay)

=68 ns - 8 ns - 1 ns - 3 ns

=56 ns

220

Rabbit 3000 Microprocessor

Page 229
Image 229
Jameco Electronics 2000, 3000 manual Example