40 PIN CONNECTOR at the computer.
The Commodore CDTV memory card connector is a proprietary 40-pin, 2.54 mm pitch interface (ITT Cannon part 252577-01) introduced with the CDTV player in 1991. It accepts battery-backed SRAM cards — the CD1401 (64 KB, CR2016 battery) and the CD1405 (256 KB, BL2325 battery) — which insert into a front-panel slot behind a removable door. The connector carries a 16-bit data bus, address lines A1–A19, separate even/odd byte chip-select lines, and a single +5 V power rail; it conforms to no third-party standard such as PCMCIA. Address lines A18 and A19 require logic-board jumpers J16 and J17 respectively to connect them to the processor bus.
| Pin | Name | Description |
|---|---|---|
| 1 | D0 | Data Bus 0 |
| 2 | D1 | Data Bus 1 |
| 3 | D2 | Data Bus 2 |
| 4 | D3 | Data Bus 3 |
| 5 | D4 | Data Bus 4 |
| 6 | D5 | Data Bus 5 |
| 7 | D6 | Data Bus 6 |
| 8 | D7 | Data Bus 7 |
| 9 | D8 | Data Bus 8 |
| 10 | D9 | Data Bus 9 |
| 11 | D10 | Data Bus 10 |
| 12 | D11 | Data Bus 11 |
| 13 | D12 | Data Bus 12 |
| 14 | D13 | Data Bus 13 |
| 15 | D14 | Data Bus 14 |
| 16 | D15 | Data Bus 15 |
| 17 | A1 | Address Bus 1 |
| 18 | A2 | Address Bus 2 |
| 19 | A3 | Address Bus 3 |
| 20 | A4 | Address Bus 4 |
| 21 | A5 | Address Bus 5 |
| 22 | A6 | Address Bus 6 |
| 23 | A7 | Address Bus 7 |
| 24 | A8 | Address Bus 8 |
| 25 | A9 | Address Bus 9 |
| 26 | A10 | Address Bus 10 |
| 27 | A11 | Address Bus 11 |
| 28 | A12 | Address Bus 12 |
| 29 | A13 | Address Bus 13 |
| 30 | A14 | Address Bus 14 |
| 31 | A15 | Address Bus 15 |
| 32 | A16 | Address Bus 16 |
| 33 | A17 | Address Bus 17 |
| 34 | R/W | Read/Write (High=Read) |
| 35 | /CSMCOD | Chip Select Odd Bytes |
| 36 | /CSMCEN | Chip Select Even Bytes |
| 37 | VCC | +5 Volts DC |
| 38 | GND | Ground |
| 39 | A18 | Address Bus 18 (Short J16 to connect A18 to processor bus) |
| 40 | A19 | Address Bus 19 (Short J17 to connect A19 to processor bus) |
Notes
- Address space = $E00000–$E7FFFF.
- Connector part number: ITT Cannon 252577-01; flat-cable harness part: 252576-01.
- The card uses battery-backed SRAM technology, not flash memory. Replacing the battery when depleted preserves stored data only if done promptly.
- A write-protect tab on the card body prevents accidental overwriting of saved data.
- Not all CDTV software titles support these memory card models.
- The connector is proprietary to Commodore; it is not compatible with PCMCIA or any other industry-standard memory card interface.
Signals
- D0–D15 — 16-bit bidirectional data bus.
- A1–A17 — Address bus lines directly connected to the processor bus; cover the base address range $E00000–$E7FFFF.
- A18 — Address bus line 18; connected to the processor bus only when logic-board jumper J16 is shorted.
- A19 — Address bus line 19; connected to the processor bus only when logic-board jumper J17 is shorted.
- R/W — Read/Write control; high selects a read cycle, low selects a write cycle.
- /CSMCOD — Active-low chip select for odd data bytes (CSMC odd, D8–D15).
- /CSMCEN — Active-low chip select for even data bytes (CSMC even, D0–D7).
- VCC — +5 V DC supply.
- GND — Signal and power return.