Tiny Z80

Business Card Sized Zilog Z80 Single Board Computer

Table of Content

• Introduction
• Specifications
• Hardware Documentation
  • Schematic and PCB Layout
  • Connectors and Jumpers
  • Bill of Materials
• Firmware Documentation
  • BIOS and OS
  • SPLD Fuse Map
• Release Notes
  • Changes
  • Known Issues
  • Wishlist

Introduction

Tiny Z80 is a business card sized (size?!) single board computer (SBC). It is mostly compatible with Easy Z80, and offers similar capabilities, including 512 KiB of battery-backed SRAM, 512 KiB Flash ROM, Z80 SIO and Z80 CTC (integrated in Z80 EIPC). Tiny Z80 includes a USB to Serial converter IC on board connected to one of the SIO ports, for ease of use with modern computers. The glue logic, including the memory paging registers is implemented using Altera MAX7000AE CPLD.

Specifications

• Processor: Zilog Z80 EIPC - Z84C15, includes Z80 CPU, Z80 SIO, Z80 PIO, and Z80 CTC
• Memory: 512 KiB battery-backed SRAM, 512 KiB Flash ROM
• Input/Output:
  • Dual RS232 serial ports, implemented using Z80 SIO integrated into Z80 EIPC
  • FT231XS USB to Serial converter connected to SIO Port A
  • Two 8-bit parallel ports, implemented using Z80 PIO integrated into Z80 EIPC
  • User controllable LED
• Bus: RC2014 compatible
• Microprocessor Supervisor:
  • Reset generation
  • SRAM battery backup
  • Power failure NMI
  • Watchdog (optional)

Hardware Documentation

Schematic and PCB Layout

Schematic - Version 1.0

PCB Layout - Version 1.0

Connectors and Jumpers

J1 - Serial_A - USB Serial

Pin	Signal Name	Description
1	VBUS	Power Supply - +5V
2	D-	USB Data -
3	D+	USB Data +
4	NC	Not Connected
5	GND	Ground

J2 - Serial_B - FTDI Header - TTL Level

Pin	Signal Name	Description
1	GND	Ground
2	RTS	RS232 / Request to Send
3	VSER	Power Supply - +5V (Optional, if F2 is installed)
4	RXD	RS232 / Receive
5	TXD	RS232 / Transmit
6	CTS	RS232 / Clear to Send

J3 - Parallel - PIO

Pin	Signal Name	Description	Pin	Signal Name	Description
1	VCC	Power Supply - +5V	2	GND	Ground
3	PA0	Port A - Data 0	4	GND	Ground
5	PA1	Port A - Data 1	6	/BSTB	Port B - Strobe
7	PA2	Port A - Data 2	8	BRDY	Port B - Ready
9	PA3	Port A - Data 3	10	PB7	Port B - Data 7
11	PA4	Port A - Data 4	12	PB6	Port B - Data 6
13	PA5	Port A - Data 5	14	PB5	Port B - Data 5
15	PA6	Port A - Data 6	16	PB4	Port B - Data 4
17	PA7	Port A - Data 7	18	PB3	Port B - Data 3
19	ARDY	Port A - Ready	20	PB2	Port B - Data 2
21	/ASTB	Port A - Strobe	22	PB1	Port B - Data 1
23	GND	Ground	24	PB0	Port B - Data 0
25	GND	Ground	26	VCC	Power Supply - +5V

J4, J5, J6 - RC2014 Bus

Pin	Signal Name	Description	Pin	Signal Name	Description
J4-1	A15	Address A15; Output
J4-2	A14	Address A14; Output
J4-3	A13	Address A13; Output
J4-4	A12	Address A12; Output
J4-5	A11	Address A11; Output
J4-6	A10	Address A10; Output
J4-7	A9	Address A9; Output
J4-8	A8	Address A8; Output
J4-9	A7	Address A7; Output
J4-10	A6	Address A6; Output
J4-11	A5	Address A5; Output
J4-12	A4	Address A4; Output
J4-13	A3	Address A3; Output
J4-14	A2	Address A2; Output
J4-15	A1	Address A1; Output
J4-16	A0	Address A0; Output
J4-17	GND	Ground	J5-1	GND	Ground
J4-18	VCC	Power Supply - +5V	J5-2	VCC	Power Supply - +5V
J4-19	/M1	Machine Cycle One; Output	J5-3	/RFSH	DRAM refresh; Output
J4-20	/RESET	Reset; Output	J5-4	N/C	Not connected
J4-21	CPU_CLK	CPU Clock; Output	J5-5	UART_CLK	UART Clock (1.8432 MHz); Output
J4-22	/INT	Interrupt; Input	J5-6	/BUSACK	DMA Bus Acknowledge; Output
J4-23	/MREQ	Memory Request; Output	J5-8	/HALT	Halt; Output
J4-24	/WR	Write Request; Output	J5-9	/WAIT	Wait; Input
J4-25	/RD	Read Request; Output	J5-10	/NMI	Non-maskable Interrupt; Input
J4-26	/IORQ	Input/Output Request; Output
J4-27	D0	Data D0; Input/Output
J4-28	D1	Data D1; Input/Output
J4-29	D2	Data D2; Input/Output
J4-30	D3	Data D3; Input/Output
J4-31	D4	Data D4; Input/Output
J4-32	D5	Data D5; Input/Output
J4-33	D6	Data D6; Input/Output
J4-34	D7	Data D7; Input/Output
J6-1	TXDA	Channel A, Transmit Data; Output	J6-2	TXDB	Channel B, Transmit Data; Output
J6-3	RXDA	Channel A, Receive Data; Input	J6-4	RXDB	Channel B, Receive Data; Input
J6-5	USR1	User Pin 1, Not connected	J6-6	USR5	User Pin 5, Not connected
J6-7	IEI	Interrupt Enable Input	J6-8	USR6	User Pin 6, Not connected
J6-9	IEO	Interrupt Enable Output	J6-10	USR7	User Pin 7, Not connected

J7 - JTAG - CPLD

Pin	Signal Name	Description	Pin	Signal Name	Description
1	TCK	Test Clock	2	GND	Ground
3	TDO	Test Data Output	4	3.3V	Power Supply - +3.3V
5	TMS	Test Mode Select	6	NC	No Connect
7	NC	No Connect	8	NC	No Connect
9	TDI	Test Data Input	10	GND	Ground

JP1 - Serial Channel A Clock Select

Position	Description
1-2 (default)	1.8432 MHz (115200 bps if using x16 mode)
2-3	Programmable using CTC channel 0

JP2 - Serial Channel B Clock Select

Position	Description
1-2 (default)	1.8432 MHz (115200 bps if using x16 mode)
2-3	Programmable using CTC channel 1

JP3 - LDO Bypass

Solder instead of U7 LDO when using a 5V CPLD

JP4 - RAM_CS, JP5 - VRAM

Solder when not using U5 CPU Supervisor to connect RAM_CS and VCC directly to the SRAM IC

Bill of Materials

Version 1.0

Tiny Z80 project on Mouser.com - View and order all components except of the PCB.

Tiny Z80 project on OSH Park - View and order the PCB.

Component type	Reference	Description	Quantity	Possible sources and notes
PCB		Tiny Z80 PCB - Version 1.0	1	Order from a PCB manufacturer of your choice using provided Gerber or KiCad files
Battery Holder	BT1	CR2032 Keystone Electronics 534-1058	1	Mouser 534-1058
Battery	BT1	CR2032	1
Capacitor	C1 - C13	100nF 0603 SMT	13	Mouser 77-VJ0603Y104JXJPBC
Capacitor	C14, C15	33pF 0603 SMT	2	Mouser 77-VJ0603A330JXACBC
Capacitor	C16, C17	47pF 0603 SMT	2	Mouser 77-VJ0603A470JXACBC
Capacitor	C18	10nF 0603 SMT	1	Mouser 77-V0603Y103KXJAC31X
Capacitor	C20, C19	10uF 1210 SMT	2	Mouser 581-TAJB106K020SNJ
Capacitor	C21	47uF SMT	1	Mouser 581-TAJC476K016TNJ
LED	D1	0603 SMT Power/Green	1	Mouser 78-VLMG1300-GS08
LED	D2	0603 SMT TX/Red	1	Mouser 78-VLMS1300-GS08, 78-VLMO1300-GS08
LED	D3	0603 SMT RX/Yellow	1	Mouser 78-VLMY1300-GS08
LED	D4	0603 SMT CPU/Blue	1	Mouser
Polyfuse	F2, F1	0.5A SMT	2	Mouser 650-MINISMDC050F-2
Connector	J1	Mini USB B	1	Mouser 649-10118194-0001LF
Connector	J2	Pin Header 1x6	1
Connector	J3	Pin Header 2x13	1
Connector	J4, J5	Pin Header 2x34, Right Angle	1	Mouser 571-9-103326-0 Note: Cut to 34 pin, remove extra pins. Use remaining 2x6 piece for J6
Connector	J6, J7	Pin Header 2x5	2
Resistor	R1, R2	27 Ohm 0603 SMT	2	Mouser 71-CRCW0603-27-E3
Resistor	R3 - R6	1 kOhm 0603 SMT	4	Mouser 71-CRCW0603-1.0K-E3
Resistor	R7 - R18	4.7 kOhm 0603 SMT	12	Mouser 71-CRCW0603-4.7K-E3
Resistor	R19 - R25	10 kOhm 0603 SMT	7	Mouser 71-CRCW0603-10K-E3
Resistor	R26	29.4 kOhm 0603 SMT	1	Mouser 71-CRCW0603-29.4K-E3
Trimmer Resistor	RV1	2 kOhm	1	Mouser 652-TC33X-2-202E, 81-PVG3G202C01R00
Tactile Switch	SW1	Tactile Switch	1	Mouser 653-B3U-1000P
Integrated Circuit	U1	Z84C15, Zilog Z80 EIPC, 16 MHz, QFP-100	1	Mouser 692-Z84C1516FSG
Integrated Circuit	U2	SST39SF040, 512 KiB Flash ROM, PLCC-32	1	Mouser 579-39SF0405INHE
Integrated Circuit	U3	AS6C4008, 512 KiB SRAM, SOP-32	1	Mouser 913-AS6C4008-55SIN
Integrated Circuit	U4	EPM7064AETC44, Altera MAX 7000AE CPLD, TQFP-44	1	Mouser 989-EPM7064AETC4410N
Integrated Circuit	U5	MAX691xWE	1	Mouser 584-ADM691AARWZ-R
Integrated Circuit	U6	FT231XS	1	Mouser 895-FT231XS-R
Integrated Circuit	U7	TPS79333-EP	1	Mouser 595-TPS79333DBVR
IC Socket	U2	PLCC32 SMD Socket	1	Mouser 649-69802-432LF
Crystal Oscillator	X1	1.8432 MHz XO91	1	Mouser 559-F3345-184
Crystal Resonator	Y1	16 MHz Crystal_GND24	1	Mouser 732-22516MF18X-G

Firmware Documentation

BIOS and OS

Tiny Z80 is supported by RomWBW v3.0.1 and later. RomWBW includes BIOS, CP/M-80 2.2, Z-System, and a collection of utilities. It also should be possible to run FUZIX on this board. Note: Edit Easy Z80 configuration (cfg_ezz80.asm), set SIO0BASE to $18 and CTCBASE to $10

CPLD Fuse Map

Tiny Z80 uses an Intel/Altera EPM7064AETC44 CPLD (U4) for address decode logic. The CPLD fuse map and the CPLD source code are provided in CPLD directory of this repository. Use free Altera Quartus II 13.0sp1 Web Edition to program the CPLD. Newer Quartus versions do not support Altera MAX7000 CPLDs.

Release Notes

Changes

• Version 1.0
  • Initial version

Known Issues

• Version 1.0
  • Front silkscreen: J7 overlaps with 100nF value of C4

Wishlist

• Version 1.0
  • None