
DS80C320/DS80C323 
5 of 42 
DIP 
21 
22 
23 
24 
25 
26 
27 
28 
PLCC 
24 
25 
26 
27 
28 
29 
30 
31 
TQFP 
18 
19 
20 
21 
22 
23 
24 
25 
SIGNAL NAME 
A8 (P2.0) 
A9 (P2.1) 
A10 (P2.2) 
A11 (P2.3) 
A12 (P2.4) 
A13 (P2.5) 
A14 (P2.6) 
A15 (P2.7) 
DESCRIPTION 
A15-A8 (Port 2) - Output
. Port 2 serves as the MSB for external 
addressing. P2.7 is A15 and P2.0 is A8. The device will 
automatically place the MSB of an address on P2 for external ROM 
and RAM access. Although Port 2 can be accessed like an ordinary 
I/O port, the value stored on the Port 2 latch will never be seen on the 
pins (due to memory access). Therefore writing to Port 2 in software 
is only useful for the instructions MOVX A, @Ri or MOVX @Ri, A. 
These instructions use the Port 2 internal latch to supply the external 
address MSB. In this case, the Port 2 latch value will be supplied as 
the address information. 
Port 3 - I/O. 
Port 3 functions as both an 8-bit bi-directional I/O port 
and an alternate functional interface for External Interrupts, Serial 
Port 0, Timer 0 & 1 Inputs, 
RD
 and 
WR
 strobes. The reset condition 
of Port 3 is with all bits at a logic 1. In this state, a weak pullup holds 
the port high. This condition also serves as an input mode, since any 
external circuit that writes to the port will overcome the weak pullup. 
When software writes a 0 to any port pin, the device will activate a 
strong pulldown that remains on until either a 1 is written or a reset 
occurs.  Writing a 1 after the port has been at 0 will cause a strong 
transition driver to turn on, followed by a weaker sustaining pullup. 
Once the momentary strong driver turns off, the port once again 
becomes both the output high and input state. The alternate modes of 
Port 3 are outlined below: 
Port 
Alternate 
Mode
P3.0 
RXD0 
Serial Port 0 Input 
P3.1 
TXD0 
Serial Port 0 Output 
P3.2 
INT0
External Interrupt 0 
P3.3 
INT1
External Interrupt 1 
P3.4 
T0 
Timer 0 External Input 
P3.5 
T1 
Timer 1 External Input 
P3.6 
WR
External Data Memory Write Strobe 
P3.7 
RD
External Data Memory Read Strobe 
EA
- Input. 
This pin must be connected to ground for proper 
operation. 
NC - Reserved. 
These pins should not be connected. They are 
reserved for use with future devices in this family. 
NC - Reserved. 
These pins are reserved for additional ground pins 
on future products. 
10-17 
11, 
13-19 
5, 7-13 
P3.0-P3.7 
10 
11 
12 
13 
14 
15 
16 
17 
31 
11 
13 
14 
15 
16 
17 
18 
19 
35 
5 
7 
8 
9 
10 
11 
12 
13 
29 
EA
- 
12 
34 
1 
6 
28 
39 
NC 
- 
80C32 COMPATIBILITY 
The DS80C320/DS80C323 is a CMOS 80C32-compatible microcontroller designed for high 
performance. In most cases it will drop into an existing 80C32 design to significantly improve the 
operation. Every effort has been made to keep the device familiar to 8032 users, yet it has many new 
features. In general, software written for existing 80C32-based systems will work on the 
DS80C320/DS80C323. The exception is critical timing since the High-Speed Microcontroller performs 
its instructions much faster than the original. It may be necessary to use memories with faster access 
times if the same crystal frequency is used. 
Application note 57 “DS80C320 Memory Interface Timing” is a useful tool to help the embedded system 
designer select the proper memories for her or his application. 
The DS80C320/DS80C323 runs the standard 8051 instruction set and is pin-compatible with an 80C32 in 
any of three standard packages. It also provides the same timer/counter resources, full-duplex serial port, 
256 bytes of scratchpad RAM and I/O ports as the standard 80C32. Timers will default to a 12 clock per