
SECTION 2 HARDWARE DESCRIPTION
4
Figure 2-1. Memory Address Detection
2.3 PORT ADDRESS DETECTION
S-100 address lines AO thru A7 are constantly monitored by
the Port Address Detection circuit. This circuit is composed of
IC 3F and part of 3E. See figure 2-2. Switches "PO" and "P1" are
used to vary the selected port address from 40 thru 43 hex. An
address match is indicated by BPA* (Bus - Port Addressed) being
asserted.
SWITCH
P1
SWITCH
P0
ADDRESS
PORT
Close
Close
Open
Open
Close
Open
Close
Open
40
41
42
43
Figure 2-2.
Port Address Detection
Table 2-2.
Port Address Selection
Comentarios a estos manuales