2 layers244 × 244 mm 6809PC-6U, the printed circuit board in 3D

6809PC-6U

6809 PC

Size: 244 × 244 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 167
Nets: 448
Pads: 1,611
Tracks, vias: 8,277, 429
Pours: 5
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 20 Jan 2025
Updated: 13 Jul 2025

Overview

6809PC-6U is an open-source printed circuit board by danwerner21, from the danwerner21/6809PC repository on GitHub. It is a 2-layer board of 244 × 244 mm with 167 parts on 448 nets, routed with 8,277 tracks and 429 vias.

It is built around the MC68B09CP, 74LS245SC and 74LS240DC, with the MAX232N, 27C256-17/J and 74LS32SC among its other parts. Its parts include 64 capacitors, 46 ICs, 35 connectors, 9 resistors and 4 diodes.

Main components

README

readme.md

6809PC

The 6809PC is a 6809 ATX format board with 512K RAM, 4K ROM, with a flexible programmable MMU, battery backed up RTC, 6551 UART, and 6 ISAish slots. This computer will run the fantastic CUBIX operating system by Dave Dunfield.

See this repo (https://github.com/danwerner21/CUBIX09) for ROM image and operating system.

System

BUGS

I have not built the 1.31 version, but it contains fixes for the only bug found in the 1.30 version which was in the ATX power switch circuit. The ICs in that circuit were not powered by standby power, they were powered by +5 which made them non-functional. Also the reset line on the ISA bus has the wrong polarity -- it should be active high. There are no known remaining bugs in the 1.31 board.

Jumper Settings

J1,J2,J5,J7,J9,J13 - ISA SLOT IRQ Selection J11 - TTL Serial Port Connection J12 - TTL Console Power

K1 - ROM BANK Selection (2-3 high bank, 1-2 Low Bank) K2 - MMU Selection (1-2 Disable on int, 3-4 Clear Task register on int)

JP1 - Reset Swithc Connection JP3 - CTS Pull Up Enable

P12 - Power Switch Connection P15 - CPU Speed Selection P18 - Serial Port Connection

Building the system

Default Memory Map

text

        $0000-$E000 - RAM
        $E000-$EFFF - Memory Mapped IO
        $F000-$FFFF - ROM

Bill Of Materials

Reference	Value	Qty	Field1	Description
C1-C4,C17	22 uF	5		Polarized capacitor
C5-C16,C18-C27,C29-C33,C36-C54,C56,C58,C62	0.1 uF	49		Unpolarized capacitor
C28	1uF	1		Polarized capacitor
C35	10uF	1		Polarized capacitor
C57	0.01 uF	1		Unpolarized capacitor
C59,C60	15pf	2		Unpolarized capacitor
C61,C63-C66	1.0 uF	5		Polarized capacitor
D1,D2	1N4148	2		Diode
D3,D4	D	2		Diode
J1,J2,J5,J7,J9,J13	IRQ Selection	6		Generic connector, double row, 02x06, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers), script generated (kicad-library-utils/schlib/autogen/connector/)
J3,J4,J6,J8,J10,J14	Bus_ISA_8bit	6		8-bit ISA-PC bus connector
J11	TTL SERIAL CONSOLE	1		Generic connector, single row, 01x06, script generated (kicad-library-utils/schlib/autogen/connector/)
J12	TTL CONSOLE PWR	1		Generic connector, single row, 01x02, script generated (kicad-library-utils/schlib/autogen/connector/)
JP1,JP3	JUMPER	2		-- mixed values --
K1	ROM SELECT	1		Generic connector, single row, 01x03, script generated (kicad-library-utils/schlib/autogen/connector/)
K2	MMU-INTA	1		Generic connector, single row, 01x03, script generated (kicad-library-utils/schlib/autogen/connector/)
P1	SHADOW ADDR	1		Generic connector, double row, 02x04, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers), script generated (kicad-library-utils/schlib/autogen/connector/)
P11	CONN_10X2	1		Generic connector, double row, 02x10, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers), script generated (kicad-library-utils/schlib/autogen/connector/)
P12	POWER_SW	1		Generic connector, single row, 01x02, script generated (kicad-library-utils/schlib/autogen/connector/)
P13	14.31818 MHz CLK	1
P14	16.000Mhz	1
P15	CPU CLOCK SPEED	1		Generic connector, double row, 02x04, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers), script generated (kicad-library-utils/schlib/autogen/connector/)
P16	CONN_4	1		Generic connector, single row, 01x04, script generated (kicad-library-utils/schlib/autogen/connector/)
P17	1.8432 MHz CLK	1
P18	SERIAL	1		Generic connector, double row, 02x05, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers), script generated (kicad-library-utils/schlib/autogen/connector/)
R1,R3	10k	2		Resistor
R2	470	1		Resistor
R4,R7,R26	4.7K	3		Resistor
R5,R6,R8	1000	3		Resistor
RR1	2200	1		9 resistor network, star topology, bussed resistors, small symbol
RR2	22K	1		9 resistor network, star topology, bussed resistors, small symbol
SW1	POWER	1		Push button switch, generic, two pins
SW2	RESET	1		Push button switch, generic, two pins
U1	74LS04	1		Hex Inverter
U2,U34,U36,U39,U45,U46	74LS244	6		Octal Buffer and Line Driver With 3-State Output, active-low enables, non-inverting outputs
U3	74LS682	1
U4	74LS86	1		Quad 2-input XOR
U5	74LS02	1		quad 2-input NOR gate
U6,U21	74LS00	2		quad 2-input NAND gate
U7,U10,U16	74LS32	3		Quad 2-input OR
U8	SRAM_512K	1		512K x 8 Low Power CMOS RAM, DIP-32
U9,U15	74LS08	2		Quad And2
U11	27C256	1		OTP EPROM 256 KiBit
U12,U22	74LS74	2		Dual D Flip-flop, Set & Reset
U17	74LS14	1		Hex inverter schmitt trigger
U18	74LS06	1		Inverter Open Collect
U19	74HCT14	1		Hex inverter schmitt trigger
U23	74LS688	1		8-bit magnitude comparator
U24,U42	74LS138	2		Decoder 3 to 8 active low outputs
U25-U28,U32,U41	74LS245	6		Octal BUS Transceivers, 3-State outputs
U29	DS1233	1
U30	74LS163	1		Synchronous 4-bit programmable binary Counter
U31	74LS240	1		Octal Buffer and Line Driver With 3-State Output, active-low enables, inverting outputs
U33	MC68B09	1		8-Bit Microprocessing unit 2.0MHz, DIP-40
U35	74LS174	1		Hex D-type Flip-Flop, reset
U37	74LS157	1		Quad 2 to 1 line Multiplexer
U38	74LS374	1		8-bit Register, 3-state outputs
U40	SRAM-32K	1		256K (32K x 8) Static RAM, 70ns, DIP-28
U43,U44	74LS257	2		Quad 2 to 1 Multiplexer
U47	M6242	1		M6242
U48	G65SC51P	1		CMOS Asynchronous Communication Interface Adapter (ACIA), Serial UART, DIP-28
U49	MAX232	1		Dual RS232 driver/receiver, 5V supply, 120kb/s, 0C-70C
X1	RTC_OSC	1	32.768 KHz	Two pin crystal

Parts

167

Qty	Value	Footprint	References
49	0.1 uF	Custom:STD_DDW_CAP	C10, C11, C12, C13, C14, C15, C16, C18, C19, C20, C21, C22, C23, C24, C25, C26 +33
12	CONN_1	MountingHole:MountingHole_3.2mm_M3_Pad_TopBottom	P2, P3, P4, P5, P6, P7, P8, P9, P10, P21, P22, P23
6	74LS244	Custom:STD_DDW_DIP20	U2, U34, U36, U39, U45, U46
6	74LS245	Custom:STD_DDW_DIP20	U25, U26, U27, U28, U32, U41
6	Bus_ISA_8bit	Custom:BUSPC_HOST	J3, J4, J6, J8, J10, J14
6	IRQ Selection	Custom:STD_DDW_PINHEAD_V_2x06	J1, J2, J5, J7, J9, J13
5	1.0 uF	Custom:STD_DDW_PCAP	C61, C63, C64, C65, C66
5	22 uF	Custom:STD_DDW_PCAP	C1, C2, C3, C4, C17
3	1000	Custom:STD_DDW_RESISTOR	R5, R6, R8
3	4.7K	Custom:STD_DDW_RESISTOR	R4, R7, R26
3	74LS32	Custom:STD_DDW_DIP14	U7, U10, U16
2	10k	Custom:STD_DDW_RESISTOR	R1, R3
2	15pf	Custom:STD_DDW_CAP	C59, C60
2	1N4148	Custom:STD_DDW_DIODE	D1, D2
2	74LS00	Custom:STD_DDW_DIP14	U6, U21
2	74LS08	Custom:STD_DDW_DIP14	U9, U15
2	74LS138	Custom:STD_DDW_DIP16	U24, U42
2	74LS257	Custom:STD_DDW_DIP16	U43, U44
2	74LS74	Custom:STD_DDW_DIP14	U12, U22
2	D	Custom:STD_DDW_DIODE	D3, D4
2	JUMPER	Custom:STD_DDW_PINHEAD_V_1x02	JP1, JP3
1	0.01 uF	Custom:STD_DDW_CAP	C57
1	1.8432 MHz CLK	Custom:STD_DDW_DIP14	P17
1	10uF	Custom:STD_DDW_PCAP	C35
1	14.31818 MHz CLK	Custom:STD_DDW_DIP14	P13
1	16.000Mhz	Custom:STD_DDW_DIP14	P14
1	1uF	Custom:STD_DDW_PCAP	C28
1	2200	Custom:STD_DDW_SIP10	RR1
1	22K	Custom:STD_DDW_SIP10	RR2
1	27C256	Package_DIP:DIP-28_W15.24mm	U11
1	470	Custom:STD_DDW_RESISTOR	R2
1	74HCT14	Custom:STD_DDW_DIP14	U19
1	74LS02	Custom:STD_DDW_DIP14	U5
1	74LS04	Custom:STD_DDW_DIP14	U1
1	74LS06	Custom:STD_DDW_DIP14	U18
1	74LS14	Custom:STD_DDW_DIP14	U17
1	74LS157	Custom:STD_DDW_DIP16	U37
1	74LS163	Custom:STD_DDW_DIP16	U30
1	74LS174	Custom:STD_DDW_DIP16	U35
1	74LS240	Custom:STD_DDW_DIP20	U31
1	74LS374	Custom:STD_DDW_DIP20	U38
1	74LS682	Custom:STD_DDW_DIP20	U3
1	74LS688	Custom:STD_DDW_DIP20	U23
1	74LS86	Custom:STD_DDW_DIP14	U4
1	CONN_10X2	Custom:ATXConnector	P11
1	CONN_4	Custom:STD_DDW_PINHEAD_V_1x04	P16
1	CPU CLOCK SPEED	Custom:STD_DDW_PINHEAD_V_2x04	P15
1	DS1233	Custom:STD_DDW_TO92	U29
1	G65SC51P	Custom:STD_DDW_DIP28	U48
1	M6242	Custom:STD_DDW_DIP18	U47
1	MAX232	Custom:STD_DDW_DIP16	U49
1	MC68B09	Custom:STD_DDW_DIP40	U33
1	MMU-INTA	Custom:STD_DDW_PINHEAD_V_1x03	K2
1	POWER	Custom:STD_DDW_TACTSW	SW1
1	POWER_SW	Custom:STD_DDW_PINHEAD_V_1x02	P12
1	RESET	Custom:STD_DDW_TACTSW	SW2
1	ROM SELECT	Custom:STD_DDW_PINHEAD_V_1x03	K1
1	RTC_OSC	Custom:DDW_STD_RTCCRYSTAL	X1
1	SERIAL	Custom:STD_DDW_PINHEAD_V_2x05	P18
1	SHADOW ADDR	Custom:STD_DDW_PINHEAD_V_2x04	P1
1	SRAM-32K	Custom:STD_DDW_DIP28_SKINNY	U40
1	SRAM_512K	Custom:STD_DDW_DIP32	U8
1	TTL CONSOLE PWR	Custom:STD_DDW_PINHEAD_V_1x02	J12
1	TTL SERIAL CONSOLE	Custom:STD_DDW_PINHEAD_V_1x06	J11

Questions

How big is the 6809PC-6U PCB?

It measures 244 × 244 mm and has 2 copper layers, 1.6 mm thick.

What parts does the 6809PC-6U use?

167 parts, built around the MC68B09CP, 74LS245SC, 74LS240DC and MAX232N. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the 6809PC-6U KiCad files?

From the danwerner21/6809PC repository on GitHub, at the commit this page was made from: the board is 6809PC-6U.kicad_pcb and its schematic 6809CPU.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the 6809PC-6U design in my own project?

Its repository states no licence, so its author keeps all rights: ask danwerner21 before reusing the design.

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/danwerner21-6809pc" title="6809PC-6U in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/danwerner21-6809pc.jpg" alt="6809PC-6U" width="1200" height="900">

A picture that opens the board, for a README

[![6809PC-6U](https://pcbkit.io/embed/boards/danwerner21-6809pc.jpg?size=s)](https://pcbkit.io/boards/danwerner21-6809pc)

Source

Repository: danwerner21/6809PC
Board file: 6809PC-6U.kicad_pcb
Commit: ffc1e19
Licence: Not stated

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