Programming features include an accumulator and six eight bit registers that can be paired as 3-16 bit registers. In addition to the general registers, a stack-pointer, program-counter, and two index (memory pointers) registers are provided. While not in the same leauge as the 80486 or 68000 series, the Z80 is extremely useful for low cost control applications. One of the more useful features of the Z80 is the built-in refresh circuitry for ease of design with DRAMs.
The Z80 comes in a 40 pin DIP package. It has been manufactured in A, B, and C models, differing only in maximum clock speed. It also has been manufactured as a stand-alone microcontroler with various configurations of on-chip RAM and EPROM.
Pin # Signal (active high unless noted)
1 A11
2 A12
3 A13 {Address bus}
4 A14
5 A15
6 CLK (clock, rising edge trig)
7 D4
8 D3
9 D5 {Data bus}
10 D6
11 +5 VDC
12 D2
13 D7
14 D0
15 D1
16 INT (Interupt Request)
17 NMI (Non-maskable Interupt Request)
18 HALT (Active low)
19 MREQ (Memory Request, active low)
20 IORQ (I/O Request, active low)
21 RD (Read, active low)
22 WR (Write, active low)
23 BUSAK (Bus Request Acknowloegmnet, active low)
24 WAIT
25 BUSRQ (Bus Request)
26 RESET
27 MI (Maskable interupt, active low).
28 REFSH (Refresh timing, active low)
29 GND
30 A0
31 A1
32 A2
33 A3
34 A4
35 A5
36 A6
37 A7
38 A8
39 A9
40 A10