Motorola MC6809 connection guide

Motorola MC6809 MC6809 DIP-40 wiring guide with power, signal assignments, and bench checks.

MC6809 DIP-40

40 contacts Current package

Motorola · Motorola P plastic (Case 711), S CERDIP (Case 734) and L ceramic (Case 715) share this top-view 40-pin assignment. On-chip oscillator.

5 V supply and bypass

Required

Apply regulated 5 V and fit a 100 nF ceramic bypass with short connections to the supply rails.

+5 V
- 5 V supply +
- VCC (7)
- C1.1
0 V
- 5 V supply −
- VSS (1)
- C1.2

Bench checks

Verify pin 1 is grounded and measure 4.75–5.25 V at pin 7.
Keep RESET asserted during supply and clock startup. The bypass capacitor is a board-level design choice.

Motorola MC6809 datasheet DS9845-R2, pp. 1–2

Connection scenarios

4 MHz crystal clock

Use a 4 MHz parallel-resonant crystal and the 24 pF load capacitors from Motorola’s example for 1 MHz bus operation. Use the crystal parameters from Fig. 7 and account for board stray capacitance.

Oscillator input
- EXTAL (38)
- Y1.1
- C2.1
Oscillator return
- XTAL (39)
- Y1.2
- C3.1
Reference
- VSS (1)
- C2.2
- C3.2
- Oscilloscope GND
Bus clock probe
- E (34)
- Oscilloscope CH1

Bench checks

Keep the crystal and both capacitors near pins 38 and 39. Use 24 pF C0G capacitors for the reference circuit.
Keep RESET low through oscillator startup. The bus timing table allows up to 100 ms oscillator start time.
Check for 1 MHz on E using a high-impedance probe. A probe on the crystal nodes can alter oscillator loading.

Motorola MC6809 datasheet DS9845-R2, Figs. 6–7 and bus timing table

MC6809 DIP-40 wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

Top view · Pin 1 at upper left · Schematic outline

Selected pin details

30 · D1

Bidirectional · Bidirectional

Data bit 1. Driven by external memory on reads and the MPU on writes. Meet the setup and hold times around E.

Motorola MC6809 datasheet DS9845-R2, pin assignment and pin descriptions

Electrical limits · Pin in the reference

Models and documents

Covers the Motorola MC6809 and MC6809E plus their A and B speed grades. On the MC6809, E and Q are outputs. On the MC6809E, both are inputs, and pins 33, 36, 38 and 39 also differ. Hitachi HD6309 and later CMOS versions require their own datasheets.

MC6809: 1.0 MHz maximum bus rate. MC6809P/S/L (0–70 °C) and MC6809CP/CS/CL (−40 to +85 °C).
MC68A09: 1.5 MHz maximum bus rate. MC68A09P/S/L (0–70 °C) and MC68A09CP/CS/CL (−40 to +85 °C).
MC68B09: 2.0 MHz maximum bus rate. MC68B09P/S/L (0–70 °C) and MC68B09CP/CS/CL (−40 to +85 °C).

Motorola MC6809 datasheet DS9845-R2· Manufacturer scan, © 1983. Pin map p. 1, electrical and bus timing pp. 2–3, crystal and reset pp. 7–8, ordering p. 35. Scan SHA-256 87037123596de83bbc44ac63fbcde3950d368d5ee30880bffaa54e23bb81ea68.
Motorola MC6809E datasheet DS9846-R2· Manufacturer scan, © 1984. Check the pin assignment, external clock thresholds and timing, TSC timing and ordering table. Scan SHA-256 42c50598f2184bc37535a8d59be60a895c14e34919d706317b18f02f73441808.
Motorola MC6809–MC6809E Microprocessor Programming Manual· Programming model, interrupt handling and vectors. Appendix B lists the two pin assignments side by side.