SIMPLE-6809

Features

• Build of Grant Searles's Simple 6809 CPU
  • Runs BASIC
• 6809 CPU
• 1.8543 MHz
• 32KB SRAM
• 16KB EPROM/EEPROM
• 68B50 Serial Port (ACIA)
  • RS-232 port
  • Header for FTDI
  • 115,200 baud
• Reset switch with optional Power Supervisor
• 95x95mm card
• (4) 6-32 mounting holes

Memory Map

• 0x0000-0x7FFF 32KB SRAM
• 0x8000-0x9FFF Free Space (8KB)
• 0xA000-0xBFFF Serial (ACIA)
• 0xC000-0xCFFF 16KB EPROM

Chipset

• MC68B09CP
• MC68B50CP
• HM62256BLP-7 32KB SRAM
• SST27SF256-70-3C-PGE EPROM

Design

• CPU

• EEPROM

• SRAM

• Logic

• ACIA

Headers / Connectors

J1 - RS-232 Serial

• DB-9 Male
• Pinout

1. N/C
2. Receive
3. Transmit
4. Loop to pin 6
5. GND
6. Loop to pin 4
7. RTS
8. N/C
9. N/C

J2 / J5 -EPROM/EEPROM Select Jumpers

27512	27256	27128	2764	28C64	PIN		PIN	2764	28C64	27128	27256	27512
A15	VPP	VPP	VPP	N/C	1 (J2)		28	VCC	VCC	VCC	VCC	VCC
A12	A12	A12	A12	A12	2		27 (J5)	PGM	WE*	PGM	A14	A14
A7	A7	A7	A7	A7	3		26	A13	N/C	A13	A13	A13
A6	A6	A6	A6	A6	4		25	A8	A8		A8	A8
A5	A5	A5	A5	A5	5		24	A9	A9		A9	A9
A4	A4	A4	A4	A4	6		23	A11	A11		A11	A11
A3	A3	A3	A3	A3	7		22	OE*	OE*		OE*	OE*
A2	A2	A2	A2	A2	8		21	A10	A10		A10	A10
A1	A1	A1	A1	A1	9		20	CE*	CE*		CE*	CE*
A0	A0	A0	A0	A0	10		19	D7	D7		D7	D7
D0	D0	D0	D0	D0	11		18	D6	D6		D6	D6
D1	D1	D1	D1	D1	12		17	D5	D5		D5	D5
D2	D2	D2	D2	D2	13		16	D4	D4		D4	D4
GND	GND	GND	GND	GND	14		15	D3	D3		D3	D3

J3 - FTDI / TTL Serial

1. GND
2. RTS* (out)
3. +5V
4. Receive (in)
5. Transmit (out)
6. N/C

J4 - 5V Power

• 2x4 header

First Unit Checkout

Install Sockets

• Machined pin sockets

Power

• Install 2x4 at J4
• Power card via J4 with 5V
• Check power pins on parts

Clock

• Install Clock parts
  • Install CPU at U5
  • Install 7.3728 MHz crystal
  • Install C5, C6

Reset

• Install U7 Power Monitor
• Install pushbutton switch SW1
• Reset button gets stretched by Power Monitor U9
• Measure reset at 68B09 U5 pin 37
• Falling edge scope cap

EPROM

• SST27C256 EEPROM
  • 32 KB part
  • Using first 16KB of EEPROM
  • J2 EEPROM pin 1 = VPP = VCC or GND
    • Jumper J2:2-3
  • J5 EEPROM pin 27 = A14 = GND
    • Jumper J5:2-3
• U1 - Do not install MAX232
  • Use FTDI connector with FTDI-49MM card

EEPROM Programming

• Program using TL-866ii plus programmer
• File = ExBasROM.hex
• Set offsets for 27SF256 part
  • Part is 32 KB
  • hex files is 16 KB
• Set From File Start Addr(Hex) to 0C000
• To Buffer Start Addr(Hex) to 00000

• Memory Buffer should look like

• Got Device ID error
• Turn off ID check

• Device programmed/verified

Test Serial

• Wire FTDI J3 to FTDI-49MM card
  • GNDs together
  • VCCs together
  • TX on FTDI-49MM to RX on card
  • RX on FTDI-49MM to TX on card

Mechanicals

Assembly Sheet

SIMPLE-6809 Rev 1 Assembly Sheet