The Spectravideo SVI-318 and SVI-328 are Z80A-based 8-bit home computers introduced in 1983 by Spectravideo International Ltd., Hong Kong. The game cartridge slot is a 30-pin female edge connector on the computer, separate from the 50-pin Super Expander bus. It carries only +5V power, ground, 14 address lines (A0–A13), 8 data lines (D0–D7), and four active-low chip-select outputs (~CCS1–~CCS4); there are no read/write or control signals, making the slot suitable for ROM cartridges only. Cartridge enables are controlled by the AY-3-8910 sound/IO chip’s Port B register, with each chip-select mapping to a 16 KB address block within the Z80’s 64 KB space.
30 PIN FEMALE EDGE at the computer.
| Pin | Name |
|---|---|
| 1 | +5v |
| 2 | +5v |
| 3 | A7 |
| 4 | A12 |
| 5 | A6 |
| 6 | A13 |
| 7 | A5 |
| 8 | A8 |
| 9 | A4 |
| 10 | A9 |
| 11 | A3 |
| 12 | A11 |
| 13 | A10 |
| 14 | A2 |
| 15 | A0 |
| 16 | A1 |
| 17 | D0 |
| 18 | D7 |
| 19 | D1 |
| 20 | D6 |
| 21 | D2 |
| 22 | D5 |
| 23 | D3 |
| 24 | D4 |
| 25 | CCS3 |
| 26 | CCS4 |
| 27 | CCS1 |
| 28 | CCS2 |
| 29 | GND |
| 30 | GND |
Notes
- The connector is a 30-pin female edge connector on the computer; cartridges insert from the top.
- Address lines A14 and A15 are absent; the slot provides only 14 bits of addressing (A0–A13).
- No RD, WR, MREQ, or IORQ signals are present — the slot is memory-mapped ROM only; write operations to the cartridge space are not possible.
- Power supply is +5V only; no ±12V rails are present on this connector (those appear only on the expansion bus).
- The address and data lines are routed in an interleaved order on the physical connector (e.g. A7, A12, A6, A13 … rather than sequential).
Signals
- +5v — +5 VDC supply (pins 1–2)
- A0–A13 — 14-bit address bus from the Z80A CPU; A14 and A15 are not present on this connector
- D0–D7 — bidirectional 8-bit data bus
- ~CCS1 — active-low chip select; addresses 0000H–3FFFH (16 KB)
- ~CCS2 — active-low chip select; addresses 4000H–7FFFH (16 KB)
- ~CCS3 — active-low chip select; addresses 8000H–BFFFH (16 KB)
- ~CCS4 — active-low chip select; addresses C000H–FFFFH (16 KB)
- GND — ground (pins 29–30)