Spark Logic

Motorola MC6800 connection guide

Motorola MC6800 DIP-40 wiring guide with power, signal assignments, and bench checks.

DIP-40

40 contacts Current package

Motorola · P plastic (Case 711), S CERDIP (Case 734) and L ceramic (Case 715) share the top-view pin assignment.

1.5 MHz maximum. MC68A00P/S/L (0–70 °C) and MC68A00CP/CS/CL (−40 to +85 °C).

5 V supply and bypass

Required

Apply regulated 5 V and fit a 100 nF ceramic bypass beside the CPU. Return both ground pins directly to the ground plane or rail.

100 nF between +5 V and 0 V+5 V100 nF0 V

Bench checks

  • With power off, verify both VSS pins 1 and 21 connect to the return.
  • Measure 4.75–5.25 V at pin 8. The 100 nF capacitor is a board-level bypass choice.

Motorola MC6800 data sheet DS9471-R2, pp. 1–2

Connection scenarios

Halt and observe the bus release

Connect a 5 V-compatible control output to HALT and a high-impedance instrument to BA and VMA. Replace the direct HALT-to-VCC idle connection from the clock example before driving HALT.

Bench checks

  • Drive HALT high during normal execution and low to request a stop. Check BA high and VMA low after the CPU halts.
  • Keep the two phases running. For a real second bus master, qualify takeover with the datasheet bus timing and a separate output-enable interlock.

Motorola MC6800 data sheet DS9471-R2, HALT signal description and Fig. 13

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

5 · VMA

Output · Control

High marks a valid external address. Low after the power-up reset settling interval and when TSC is asserted.

Motorola MC6800 data sheet DS9471-R2, pin assignment and signal descriptions

Electrical limits · Pin in the reference

Models and documents

Covers MC6800, MC68A00 and MC68B00 as documented in DS9471-R2. The MC6802 and MC6808 use different pin assignments. The term “6800 interface” on a display refers to its host bus protocol and has a module-specific pinout.

MC6800
1.0 MHz maximum. MC6800P/S/L (0–70 °C) and MC6800CP/CS/CL (−40 to +85 °C).
MC68A00
1.5 MHz maximum. MC68A00P/S/L (0–70 °C) and MC68A00CP/CS/CL (−40 to +85 °C).
MC68B00
2.0 MHz maximum. MC68B00P/S/L (0–70 °C) in DS9471-R2.