Commodore Amiga A500 Technical Reference Manual page 43

14/16 0000 0000
=
Low byte of manufacturer's number
40142 0000 0000
=
Because this PIC does not generate INTs
When you want to program your own ID PAL, just work back t o the
equations. First determine what ID pattern you need by reading
about the nibbles in the spec. Write down a table of ones and zeros.
Invert all of these except nibbles
00.02.40,
and
42.
Then, doing one
data line at time, write a product term for each binary zero that you
want to output from the ID PAL.
Passing CONFl&OUT* The equations for CONFIGOUT* in this implementation make two
feedback latches in the PAL. The first latch PRECONFIG-OUT* is set
during the bus cycle in which the processor does a write t o the ad-
dress register. In fact, in this design the rising edge of PRECONFI-
G-OUT latches the final Address value into the address latch.
The second latch outputs CONFIG-OUT*. This latch goes active after
AS* goes inactive a t the end of the bus cycle in which the new ad-
dress was written. Notice that CONFIG-OUT* enables the address
latch
U1,
so it now provides the new address range t o the compara-
tor.
CONFIG-OUT* enables the next PIC in the chain, and remains active
until a system reset or power down occurs.
TABLE 3-1 T I M I N G SPECIFICATIONS
Timing Requirements for Backplane
TIMING REQUIREMENTS FOR BACKPLANE
Num
1
2
3
4
5
6
Characteristic
AS*
UDS* LDS* Delay
Address
23-1
delay
7M(S4 RISE) to Data Enable during Read
7M (S4 RISE) to Data Valid
Data
15-0
Delay to Output
SLAVEIN or SLAVE to SLAVEOUT Delay
Min
2
2
0
0
Max
8
8
35
8
25
Unit
ns
ns
ns
ns
ns
ns