Spark Logic

MOS 6502 connection guide

MOS 6502 DIP-40 wiring guide with power, signal assignments, and bench checks.

DIP-40

40 contacts Current package

MOS Technology / Commodore Semiconductor Group · MPS plastic and MCS ceramic use the same top-view 40-pin map.

1 MHz maximum. MPS6502 plastic or MCS6502 ceramic.

5 V supply and bypass

Required

Supply VCC from a regulated 5 V rail and connect both VSS contacts. Fit a 100 nF ceramic bypass close to VCC and a short ground return.

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

Bench checks

  • With power off, check continuity from pins 1 and 21 to the ground rail.
  • Measure 4.75–5.25 V at pin 8 before releasing reset. The bypass capacitor is a board-level design choice.

Commodore Component Data Catalog (1981), pp. 2-7 and 2-11

Connection scenarios

Clock and reset bring-up

Use a continuous 1 MHz logic clock and a separately controlled active-low reset output. This connection assumes the 5 V supply circuit.

Bench checks

  • Provide the IRQ and NMI bias shown in the interrupt circuit.
  • At 1 MHz, measure the Φ0 IN pulse width at 1.5 V. The 1 MHz table specifies 460–520 ns pulse width and at most 10 ns rise and fall times. Hold /RES low for at least two complete cycles after VCC reaches 4.75 V.
  • Verify that the boot ROM provides a low byte at 0xFFFC and a high byte at 0xFFFD. Observe the vector reads before checking SYNC for the first opcode fetch.

Commodore Component Data Catalog (1981), signal descriptions and clock timing

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

8 · VCC

Supply · Power

Regulated 5 V supply. Decouple to VSS close to the package.

Commodore Component Data Catalog (1981), pp. 2-1–2-2 and 2-11

Electrical limits · Pin in the reference

Models and documents

Covers the MOS Technology / CSG NMOS 6502 map. The related 6503–6507 and 6512–6515 have their own maps in the catalog. WDC W65C02S is a distinct CMOS part with different pin assignments and timing.

6502
1 MHz maximum. MPS6502 plastic or MCS6502 ceramic.
6502A
2 MHz maximum. MPS6502A plastic or MCS6502A ceramic.
6502B
3 MHz maximum. MPS6502B plastic or MCS6502B ceramic. See the 1982–1983 catalog for 3 MHz timing.
  • Commodore Component Data Catalog (1981)· Manufacturer catalog scan. Cross-reference p. 1-3, MPU signals and electrical data pp. 2-1–2-10, 6502 pinout p. 2-11. Scan SHA-256 ddc2be52d8b14c99b28e0a2d2d116bcaa1c4c241b4005e06b4459d96e2566902.
  • MOS Technology Data Catalog (1982–1983)· Manufacturer data catalog. NMOS MPU order codes on p. 2-14 and 1, 2 and 3 MHz timing on p. 2-18. Scan SHA-256 1a6152082a15479e893a9c3391cafc4aba135dfae0613a96fbcbe12ac44248ca.
  • WDC W65C02S datasheet· Separate CMOS derivative. Compare its pin assignments and electrical conditions before designing a replacement.