adc0804-mdc National Semiconductor Corporation, adc0804-mdc Datasheet - Page 28

• Manufacturer Part Number: adc0804-mdc
• Description: 8-bit Up Compatible A/d Converters
• Manufacturer: National Semiconductor Corporation

www.national.com
Functional Description
4.2 Interfacing the Z-80
The Z-80 control bus is slightly different from that of the
8080. General RD and WR strobes are provided and sepa-
rate memory request, MREQ, and I/O request, IORQ, sig-
nals are used which have to be combined with the general-
ized strobes to provide the equivalent 8080 signals. An
advantage of operating the A/D in I/O space with the Z-80 is
that the CPU will automatically insert one wait state (the RD
and WR strobes are extended one clock period) to allow
more time for the I/O devices to respond. Logic to map the
A/D in I/O space is shown in Figure 14 .
SAMPLE PROGRAM FOR Figure 13 INS8048 INTERFACE
(Continued)
FIGURE 13. INS8048 Interface
28
Additional I/O advantages exist as software DMA routines
are available and use can be made of the output data
transfer which exists on the upper 8 address lines (A8 to
FIGURE 14. Mapping the A/D as an I/O Device
for Use with the Z-80 CPU
DS005671-21
DS005671-23
DS005671-A0