Z80 Microprocessor Kit

Construction Manual
 Z80 MICROPROCESSOR KIT
CONSTRUCTION MANUAL

CONTENTS
INTRODUCTION.....................................................................................3

COMPLETE ASSEMBLED KIT...............................................................4

PREPARING FOR ASSEMBLY...............................................................5

ASSEMBLY STEPS................................................................................6

TROUBLESHOOTING...........................................................................25

PARTS LIST............................................................................................27

2
 INTRODUCTION

This construction manual provides steps to assemble the Z80 microprocessor kit.

Preprogrammed IC chips are 1) monitor ROM 27C256, 2) Programmable Logic Device,

PLD GAL16V8 and 3) AT89C2051 microcontroller.

Be advised, 95% that causes not working circuit is from soldering! Good soldering point
makes the current flow easily. Bad soldering points may causes high impedance path,
consequences the distorted pulse signal! The Z80 will not functioning properly!

When pick the PCB, do not touch the soldering pad! Pick it with the board border only!

For those who live in dry and cold area, electrostatic discharge may zaps the CMOS chips.
Keep them at the low impedance sheet, like aluminum foil.

3
 COMPLETE ASSEMBLED KIT

RS232C connector, DB9 male

DC jack +9V
32kB Static RAM
Preprogrammed Z80 CPU Preprogrammed Preprogrammed
monitor ROM PLD microcontroller

LCD
Contrast adj.

Homemade keypad sticker using Inkjet printer SW4, slide switch selects
(vector file is available for download) between INTR key or 10ms tick

4
 PREPARING FOR ASSEMBLY

Tools

1. The example of soldering tools is shown below. Main tools are soldering iron, solder lead,
wire cutter. Voltmeter is for checking +5V power supply.

Author also has the logic probe, it can check the oscillator running easily. No need the
expensive oscilloscope.

5
 ASSEMBLY STEPS

□ 1.Check the PCB, no wire or conductive parts on both sides. Remember do not touch
the PCB pad with finger. Pick it at the board border. The board comes with presoldered
transient voltage suppressor, D2.

6
□ 2.Check the transient voltage suppressor, D2 on the PCB. The gray line on the chip is
cathode pin! It must be soldered as shown below.

□ 3.We begin with low profile devices. Insert Y1, XTAL 3.579MHz. To prevent the Xtal
case touch the PCB, we may use two pieces of tick paper insert at the bottom. Use one
finger press it while soldering at the soldered side.

7
□ 4. Insert C1, 100pF ceramic disc capacitor then followed with resistors. Place them in
axial direction.

For resistors and capacitors, we can bend the legs to make it in place. So we can solder it
easily.

8
Finished soldering point should look like this.

Remember, place the soldering iron's tip to touch to the pad and leg for 1-2 seconds, then
put the solder wire at the tip, count one, two three, then take them out.

Do not lift the tip up and down! Enough solder will make the finished work like PAGODA
and looks shine!

Cut the legs, we can insert another parts.

9
□ 5. Now insert multilayer capacitors, 100nF and R12, R PACK. Solder it.

□ 6. Insert R16, R PACK. Pin 1 of R pack is a dot point! Soldering R pack many need
your finger to press it.

Then insert and solder electrolytic capacitors, 10uF. All electrolytic capacitors has polarity.
Longer leg is positive, put it to the square footprint (with + indicator)!

10
□ 7. The voltage regulator, 7805 is TO220 package, we can bend the legs like this.

The TAP pin is GND for heatsink. We can solder it to the pad directly. The ground plan will
be heatsink of the voltage regulator. You can tighten the TAP to the PCB with M3 nut and
washer as well.

11
□ 8. We can insert the IC socket and the rest parts.

For seven segment LED, we may solder only one pin beforehand. Then check the position,
both should be line up on the same level.

We can adjust them by putting the solder tip, to make it slightly movable. Use finger to
move it, make it in position.

12
□ 9. The dot LED has polarity!, the flat side is CATHODE pin! The footprint for LED
has square one for ANODE pin! Solder it only one pin beforehand, so we can adjust it in
position easily. When it was in good position, finish the rest pins.

Again SW4 is not easy to stand, just solder one pin, then adjust the position with finger
while soldering.

D14 also has polarity. Cathode pin has black line!

Q1 and Q2 are PNP transistors. Place them in position the same as symbol on the PCB!

13
□ 10. Insert DC jack, the positive pin will need a saw files for trimming.

Insert D4, protection diode. Insert C6, it has polarity! Recheck before solder them.

14
C4 can be placed axially to make it looks good.

15
VB1 is DB9 male type connector.

16
□ 11. Insert TACT switches, 36 keys. Key must be pressed until locked with clicking
sound!

Then solder it. To make sure that all keys are in placed, turn the board back, recheck all keys
are the same level! Some key may springs back, press it until click!

17
□ 12. Small speaker can be placed at the bottom layer and have hot glue to fix it.

18
□ 13. Before insert the IC chips, check +5V by powering the board with AC adapter.

The DC input accepts from +9VDC to +12VDC. The 7805 needs at least +2V dropped
voltage. Use a volt meter check at test points TP1+5V and TP2 for GND pin. If it was nearly
+5V, it works fine. Then remove the power.

Insert the IC chips carefully. Recheck the pin position. See the example below picture.

19
Pin 1 has indicator on the IC chips. Shown Zilog Z80 CPU and monitor EPROM, 27C256.

The quartz window of the EPROM can be opened for showing student to see the silicon
chip.

However if you like to close it with small sticker, then you can make it. The normal light or
even sunshine can not kick the charge that stored in the floating gate of the FET in the
CMOS structure. To kick it, you will need strong UV with wavelength about 253.7 nm.

Read more at http://en.wikipedia.org/wiki/EPROM

20
Text LCD with 16-pin socket for plugging to the 16-header on the board.

Remember, plugging/removing the LCD must be done when the board is powered off!

21
Your first computer shall look like this when powers it on. For LCD, adjust R18 to make the
first line appears.

Building the computer is easy and fun!

Let us test the Z80 to execute our program by entering the Z80 instructions in hex code.

Press key PC, 3E, +, 01,+, D3,+, 40,+ , 76, PC, GO.

Did you see the binary number 0000 0001 on the GPIO1 LED? We program the Z80 to
write the accumulator contents to the 8-bit GPIO1. This brings the internal data to outside
realworld!

The program is simple. It has only three instructions. The hex code is only five bytes.

1800 3E 01 LD A, 1 ; load accumulator with 1

1802 D3 40 OUT (40H),A ; write to port 40H
1804 76 HALT ; Halt the CPU

22
You can change the value to be loaded easily at the 2 nd byte located at address 1801. Then
see the change when press key GO again. How easy it is!

Another example of displaying text on LCD. After the LCD initialized, we can use built-in
LCD drivers to print text or ASCII letter on screen. We will learn how to use LCD with the
Z80 programming lab book.

23
Before take a rest after completed assembly, let us enter the hex code for running LED.

line addr hex code label instruction comment

---- ---- -------- ----- –------------ –--------------
0001 1800 .ORG 1800H
0002 1800
0003 1800 GPIO1 .EQU 40H
0004 1800
0005 1800 3E 01 MAIN LD A,1
0006 1802
0007 1802 D3 40 LOOP OUT (GPIO1),A
0008 1804 CD 0C 18 CALL DELAY
0009 1807 CB 07 RLC A
0010 1809 C3 02 18 JP LOOP
0011 180C
0012 180C
0013 180C 11 FF FF DELAY LD DE,-1
0014 180F 21 00 10 LD HL,1000H
0015 1812 19 LOOP2 ADD HL,DE
0016 1813 38 FD JR C,LOOP2
0017 1815 C9 RET
0018 1816
0019 1816 .END
0020 1816
tasm: Number of errors = 0.

The program is simple forever loop writing the accumulator contents to the GPIO1 LED.

Let us entering the hex code with hex key and + key now.

Started at 1800, 3E, 01, D3, 40, CD, 0C, 18,..... until 38, FD and last byte C9. Then press
PC, GO. What is happening?

Then take a rest and have your time to learn more how to program the Z80 with the lab
book.

Have fun!

24
 TROUBLESHOOTING

PROBLEM CAUSE ACTION

No display, no power LED 1. no power from AC adapter 1. Check AC outlet
2. wrong polarity jack 2. correct the jack polarity,
3.wrong direction of use new adapter
protection diode, D4 3. correct diode direction
No display, power LED lit 1. wrong IC chip insertion 1. correct chip position
2. wrong monitor program 2. reprogram the monitor
3. wrong PLD code EPROM
4. oscillator is not running 3. reprogram PLD
5. CPU is not reset 4. check XTAL soldering, R1
and R2 must be 1k, C1 must
be 100pF
5.wrong C2 polarity, check
TP4 with logic probe, press
RESET key will make it
logic “low”.

No display on GPIO1 LED 1. wrong direction of D14 1. correct the direction

2. wrong direction of LED 2. correct Cathode/Anode
pins
No beep when press key 1. no speaker 1. solder the speaker
2. wrong position of Q2 2. correct the position of Q2
Heat up at voltage regulator, 1. DC input is much higher 1. Lower input DC voltage
U9 7805 than +7V
No display on LCD 1. wrong insertion position 1. correct the position

No back-light on LCD 1. no R17 installed 1. install R17

2. R17 is higher resistant 2. use 5-10 Ohms for R17
3. LCD module has no back- 3. use LCD module with
light back-light
4. back-light pins is not the 4. use LCD module with
same as schematic correct back-light pins
Load/Send hex file problem 1. terminal is not set correct 1. set terminal for 2400 bit/s,
format 8-data bit, no parity, one stop
2. Z80 kit stops loading bit, no flow control.
2. File is not Intel HEX file.
3.RS232 cable is not cross Ensure the file is Intel HEX
cable. file.
3. check the cable, it must be

25
 4. Send hex file displays cross cable
unreadable letters
4. correct terminal settings.

10ms tick LED, D15 is not 1. wrong polarity of D15 1. correct the polarity
blinking 2. AT89C2051 is not 2. reprogram the
programmed microcontroller

Some key has no response 1.not yet solder it 1. check and solder it

26
PARTS LIST
Capacitors
Semiconductors
C1 100pF ceramic
U1 Z80 40-pin DIP microprocessor C2,C3,C15,C16,C17 10uF electrolytic
U2 27C64 or 27C256 EPROM C4 100uF electrolytic
U3 HM62256B 32kB SRAM C5 10uF 16V electrolytic
U4 74LS14 inverter C6 1000uF 16V electrolytic
U5 74HC74 Dual D-type flip-flop C7,C8,C9,C10,C11 0.1uF multi layer
U6 GAL16V8B programmable logic device C12,C13 0.1uF multilayer
U7 74LS90 decade counter C14 10uF 10V electrolytic
U8 AT89C2051 20-pin microcontroller C18 0.1uF multilayer
U9 LM7805/TO voltage regulator
U11,U10 LTC-4727JR 4-digit 7-segment LED Additional parts
U12,U14,U16 74HC573 8-bit latch
U13 CD4001 quad NOR gate JP1 HEADER 20X2
U15 74HC541 tri-state buffer JR1 CONN RECT 16 pins
U17 MAX232A rs232 converter J1 DC input JACK
D1,D6,D7,D8,D9,D10,D11, 3mm LED J2 HEADER 3 pins
D12,D13,D15 LS1 8 Ohms SPEAKER
D2 TVS5V_SOD123 transient voltage
suppressor SW1 RESET 12mm tact switch
D4 1N4007 rectifying diode SW2 INTR 12mm tact switch
D14 1N5226A +3.3V zener 500mW SW3 MONITOR 12mm tact switch
Q2,Q1 BC557 PNP transistor SW4 slide switch-SPDT
D3 POWER 3mm LED
D5 TONE 3mm LED S1,S2,S3,S4,S5,S6,S7,S8, 12mm TACT switch
S9,S10,S11,S12,S13,S14,
Resistors (all resistors are 1/8W +/-5%) S15,S16,S17,S18,S19,S20,
S21,S22,S23,S24,S25,S26,
R1,R2,R9 1k S27,S28,S29,S30,S31,S32,
R3,R4,R5,R6,R8,R18 10K S33
R7,R19 680 Ohms
R10 2k VB1 DB 9, Male connector
R16,R12 10k RESISTOR SIP 9 Y1 XTAL 3.579MHz
R13 4.7k PCB double side plate through hole
R14 330 Ohms LED cover Clear RED color acrylic plastic
R17,R15 10 Ohms Keyboard sticker printable SVG file

27
 5 4 3 2 1
TP3
VCC 1
Y1
CLK
3.579MHz
U2 27C64/27C256 HM62256B
U1 U3
U4A U4B M1 27 30 A0 10 A0 10 11 D0
D M1 A0 A1 A0 D0 A1 A0 D0 D1 D
U5A 31 9 11 9 12
A1 A1 O0 A1 D1
4

1 2 3 4 MREQ 19 32 A2 8 12 D1 A2 8 13 D2
CPU_CLK IORQ MREQ A2 A3 A2 O1 D2 A3 A2 D2 D3
2 5 20 33 7 13 7 15
PR

D Q WR IORQ A3 A4 A3 O2 D3 A4 A3 D3 D4
22 34 6 15 6 16
C1 RD WR A4 A5 A4 O3 D4 A5 A4 D4 D5
74LS14 74LS14 3 21 35 5 16 5 17
100pF CLK RD A5 A6 A5 O4 D5 A6 A5 D5 D6
36 4 17 4 18
R1 R2 RFSH A6 A7 A6 O5 D6 A7 A6 D6 D7
6 28 37 3 18 3 19
CL

Q REFSH A7 A8 A7 O6 D7 A8 A7 D7
38 25 19 25
74HC74 HALT A8 A9 A8 O7 A9 A8
18 39 24 24
VCC HALT A9 A10 A9 A10 A9
1

40 21 21
1k 1k WAIT A10 A11 A10 A11 A10
24 1 23 23
WAIT A11 A12 A11 A12 A11
2 2 2
XTAL INT A12 A13 A12 A13 A12
16 3 26 26
INT A13 A14 RD A13 A14 A13
17 4 22 1
NMI A14 A15 ROMCE OE A14
5 20
*RESET A15 CE RAMCE
26 27 20
VCC RESET D0 PGM RD CE
14 1 22
BUSRQ D0 D1 VCC VPP WR OE
25 15 27
BUSAK BUSRQ D1 D2 0x0000-0x0FFF (4kB) WE
23 12
R3 VCC BUSAK D2 D3 0x1000-0x8FFF
8
10k TP4 CPU_CLK D3 D4
6 7
CLK D4 D5
9
D5 D6
10
10

U5B

VSS
1 D6 D7 D0
C SW1 13 D0 C
D7 D1
12 9
PR

D Q D2 D1
RESET Z80 D2

29
RESET 11 VCC D3
CLK D4 D3
U6
D5 D4
+ C2 8
CL

10uF Q RESET ROMCE D6 D5

MREQ 2 12
IORQ I I/O/Q D7 D6
74HC74 3 13 RAMCE
I I/O/Q D7
13

R4 R5 R6 A6 4 14
I I/O/Q GPIO1
10k 10k 10k A7 5 15
VCC A12 I I/O/Q RD
6 16 LCD_E RD
A13 I I/O/Q
7 17 PORT0
A14 I I/O/Q WR
8 18 PORT1 WR
A15 I I/O/Q
9 19 PORT2
WAIT I I/O/Q
U4C A0 1
BUSRQ A1 I/CLK
U7 11
NMI I/OE
14 12 5 6
M1 A QA
1 9
B QB select INTR source INTR GAL16V8B
8 A0 JP1
QC SW4 A11 RD
11 74LS14 SW2 A1
QD A12 1 2 WR
BREAK 2 1
R0(1) INT VCC A13 3 4 BUSAK
3 2
R0(2) A14 5 6 WAIT
6 3
R9(1) U8 Programmable timer A15 7 8 BUSRQ
B 7 B
VCC R9(2) R7 CPU_CLK 9 10 *RESET
680 D4 11 12 M1
74LS90 TXD 2 12
P3.0/RXD P1.0/AIN0 VCC VCC D3 13 14 RFSH
3 13
P3.1/TXD P1.1/AIN1 D5 15 16
6 14
P3.2/INTO P1.2 D6 17 18 A0
7 15
P3.3/INT1 P1.3 R19 VCC D1 D2 19 20 A1
8 16
C3 R8 P3.4/T0 P1.4 680 21 22 A2
9 17 LED
10k P3.5/T1 P1.5 D15 D7 23 24 A3
+ 18
10uF P1.6 C4 D0 25 26 A4
19 +
XTAL P1.7 D2 100uF D1 27 28 A5
U4D 5
XTAL1 INT 29 30 A6
SW3 4
XTAL2 TVS5V_SOD123 31 32

3
9 8 LED R9 NMI A7
Tick 100Hz HALT HALT 33 34 A8
RESET 1 11 BC557 2
VCC RST/VPP P3.7 Q1 MREQ 35 36 A9
MONITOR
IORQ 37 38 A10
74LS14 20
VCC R10 2k 1k 39 40
D3

1
HEADER 20X2
AT89C2051
POWER Expansion Bus
+5V
TP1 U9 J1
D4 +5V VCC
VCC LM7805/TO DC input
+5V 3 1 2 1 1
A 1 VOUT VIN A
VCC
C7 10uF 16V

GND
+ + 1N4007

2
C8 C9 C10 C11
C18 C5 C12 C13 C6
100nF 0.1uF 0.1uF 0.1uF 0.1uF
TP2 0.1uF 0.1uF 1000uF 16V
Title

2
DC2 Z80 MICROPROCESSOR KIT
GND 1
0.1uF Size Document Number Rev
B <Doc> 2
Date: Saturday, January 17, 2015 Sheet 1 of 3
5 4 3 2 1
 5 4 3 2 1
+5V VCC
D0
D1 D0 VCC
D2 D1
D3 D2
D4 D3 U10 U11
U12 0x02
D5 D4
D6 D5 D0 E A A
D6 2 19 14 14
D7 D1 1D 1Q G B A B A
D7 3 18 16 16
D D2 2D 2Q F C B C B D
4 17 13 13
D3 3D 3Q A D C D C
5 16 3 3
D4 4D 4Q B E D E D
6 15 5 5
D5 5D 5Q C F E F E
7 14 11 11
D6 6D 6Q DP G F G F
8 13 15 15
D7 7D 7Q D DP G DP G
U13A 9 12 7 7
8D 8Q DP DP
WR 1
3 11
DIGIT1

DIGIT2

DIGIT3

DIGIT4

DIGIT1

DIGIT2

DIGIT3

DIGIT4
LE
2 1 4 4
VCC OE L1L2L3 L1L2L3
4001 20
VCC
LTC-4727JR LTC-4727JR
J2
1

8
74HC573
1
7-segment test 2
PORT2 3
U14 0x01 CON3
D0 2 19 PC0
D1 1D 1Q PC1
3 18
D2 2D 2Q PC2
4 17
D3 3D 3Q PC3 10k RESISTOR SIP 9 R12 VCC
5 16
D4 4D 4Q PC4 PC0
C 6 15 2 1 C
D5 5D 5Q PC5 PC1
7 14 3
D6 6D 6Q PC6 PC2
8 13 BREAK 4
D7 7D 7Q PC7 SPEAKER PC3
9 12 5
8D 8Q PC4 6
11 PC5 7
LE
RESET 1 8
VCC OE 0x01 9
20 PC5 C
VCC PC4
74HC573 PC3
PC2
PC1
U13B PC0
WR 5
4 U4E
PORT1 6 TXD
11 10

1
4001 R13
S1 S2 S3 S4 S5 S6 SPEAKER 2 Q2
BC557
0x00 U15 74LS14 4.7k

3
D0 18 2 PA0 VCC
D1 Y1 A1 PA1
B 17 3 S7 S8 S9 S10 S11 S12 B
D2 Y2 A2 PA2 R14
16 4 D5 LS1
D3 Y3 A3 PA3
15 5
D4 Y4 A4 PA4
14 6
D5 Y5 A5 PA5 330
13 7 TONE
D6 Y6 A6 PA6
12 8 S13 S14 S15 S16 S17 S18 SPEAKER
D7 Y7 A7 +5V
11 9 S19
Y8 A8 R15
1
G1 VCC 10
19 S20 S21 S22 S23 S24 S25
G2
20
VCC
74HC541 10k RESISTOR SIP 9 R16 VCC
RXD PA0 2 1
S26 S27 S28 S29 PA1 3
U13C U4F PA2 4
8 PA3 5
RD PA4
10 13 12 6
9 PA5 7
PORT0 PA6
S30 S31 S32 S33 8
4001 74LS14 9
C
A A
Title
Z80 TRAINER KIT
Size Document Number Rev
B <Doc> 2
Date: Saturday, January 17, 2015 Sheet 2 of 3
5 4 3 2 1
 5 4 3 2 1
D0 RD
D1 D0 VCC RD +5V VCC
+5V
D2 D1 WR
D3 D2 WR
D4 D3 VCC
0x40 +5V
D5 D4
D6 D5
U16
D6
D7 10uF 10V 10uF C15
D7 D0
+
2 19 C14

+
D D1 1D 1Q D
3 18
D2 2D 2Q
4 17 U17
D3 3D 3Q
5 16 2 1
D4 4D 4Q VB1 V+ C+ 10uF
6 15 3
D5 5D 5Q C1-
7 14 5 6 4
D6 6D 6Q C16 V- C2+
8 13 9 5
D7 7D 7Q + C2-

+
U13D 9 12 4 C17
WR 8D 8Q 10uF
12 8
11 11 3 14 11 TXD
LE T1OUT T1IN
GPIO1 13 1 7 7 10
VCC OE T2OUT T2IN
2 13 12 RXD
R1IN R1OUT
4001 20 6 8 9
VCC R2IN R2OUT
1
D6 D7 D8 D9 D10 D11 D12 D13
74HC573 SUB-D 9, Male (cross cable) MAX232A
RESET LED LED
D14
1N5236A
16x2 text LCD interface
C C
JR1
+5V 8-bit Binary display LED x8
16 R17 10
16
15
15 D7
14
14 D6
13
13 D5
12
12 D4
11
11 D3
10
10 D2
9
9 D1
8
8 D0
7
7
6 LCD_E
6 R/W A1
5 A1
5 RS A0
4 A0
4
3
3
2
2
1
1
CONN RECT 16 +5V
+5V VCC
2

B 1 3 B
VCC
R18
10K
A A
Title
Z80 TRAINER KIT
Size Document Number Rev
B <Doc> 1
Date: Saturday, January 17, 2015 Sheet 3 of 3
5 4 3 2 1
NOTE

28