Sinclair ZX Interface 2
| Sinclair ZX Interface 2 | |
|---|---|
 |
|
| A ZX Interface 2 with its cartridge slot uncovered and one joystick socket cover removed; the connector for the Spectrum is at the front (photo: ccwoodcock, CC BY 2.0) | |
| Manufacturer | Sinclair Research |
| Type | Joystick interface and ROM cartridge port |
| Release date | September 1983[1] |
| Price | £19.95[1] |
| Interface | ZX Spectrum expansion edge connector; ZX Printer through connector |
| Compatible | Sinclair ZX Spectrum, directly or behind a Sinclair ZX Interface 1 |
| Model | Order code 8501; IC1 custom chip (HT62001 in the 1985 parts list) |
| Connectivity | Two 9-way D joystick sockets; ROM cartridge slot |
The Sinclair ZX Interface 2 is the joystick and ROM cartridge interface that Sinclair Research launched for the Sinclair ZX Spectrum at the end of September 1983, at £19.95.[1] It plugs into the Spectrum's expansion connector, or into the back of a Sinclair ZX Interface 1, and gives two joystick sockets for nine-way D joysticks, a slot for 16 KB ROM cartridges, and a through connector for the Sinclair ZX Printer.[2] Paul Farrow records its order code as 8501.[3]
Hardware
[edit | edit source]The interface is one printed circuit board with a single integrated circuit and its connectors.[2] There are no capacitors on the 1985 circuit diagram or in the parts list, and no supply circuit: the chip runs from the Spectrum's +5 V.[2] Paul Farrow has photographed at least two issues of the board, although the servicing manual lists no modifications.[3][2]
| Ref | Part |
|---|---|
| IC1 | Custom chip ("ULA"), listed as MCE HT62001, in a socket |
| SK1 | 28-way edge connector |
| SK2 | 15-way edge connector |
| SK3, SK4 | 9-way D joystick sockets |
Source: Table 5.7.[2] The servicing manual describes IC1 as a custom CMOS chip in a socket on the board.[2] The chip on the board in Paul Farrow's photograph is marked MT62001 and MCE 8344, and Spectrum for Everyone also calls it the MT62001 when comparing it with the Amstrad 40057 in the grey +2.[3][4]
Joysticks
[edit | edit source]The chip uses address lines A0, A11 and A12 with IORQ and RD to read the two sockets, and each joystick appears to programs as a row of number keys: joystick 1 as keys 6 to 0 and joystick 2 as keys 1 to 5.[2][5]
| Pin | SK3 | SK4 | Function |
|---|---|---|---|
| 1 | K9 | K4 | Up |
| 2 | K8 | K3 | Down |
| 3 | K6 | K1 | Left |
| 4 | K7 | K2 | Right |
| 6 | K0 | K5 | Fire |
| 8 | 0 V | 0 V | Common |
K1 to K9 are keyboard keys 1 to 9; pins 5, 7 and 9 are not used.[2] From BASIC, IN 61438 reads joystick 1 and IN 63486 joystick 2.[5] The ports are not compatible with the Kempston interface, so most games released before the Interface 2 do not work with them.[6]
ROM cartridges
[edit | edit source]A cartridge holds a 16 KB ROM. When it is plugged in, it ties the Spectrum's /ROMCS line to +5 V, which switches off the Spectrum's own ROM so the cartridge appears in its place; there is no paging back to the BASIC ROM or to the Interface 1's ROM.[3][1] The slot's contacts and the cartridges' are gold-plated.[3] Ten titles were sold commercially, Jetpac and Space Raiders among them.[6]
Care and fault finding
[edit | edit source]- Connect the interface, and insert or remove cartridges, only with the Spectrum switched off. Sinclair's card says never to insert or remove a cartridge with the power on, and there is nothing in the design to stop it.[5][3] Joysticks can be plugged in with the power on.[5]
- Clean the Spectrum's edge connector, the interface's own edge connector and the cartridge contacts. The servicing manual cleans edge-connector fingers with an eraser or a cleaning fluid on a small brush, then a lint-free cloth.[2]
- To open the case, turn the interface over and remove the four cross-head screws; the base lifts away and the board comes out of the top cover. Refit the board the right way round.[2]
- Before applying power to a suspect unit, check for short circuits between 0 V (pin 6b of the Spectrum connector) and +5 V (3b) and +9 V (4b).[2]
- Test it with a games cartridge, two joysticks and a ZX Printer connected, and check every function. If one fails, switch off and replace IC1, using proper extraction and insertion tools for the socketed chip. ZX Printer faults through the rear connector can only be broken connections, because the printer signals pass straight through.[2]
- The manual's modification history, dated October 1985, records no changes to the Interface 2: "No problems have to date arisen with this unit".[2]
Documentation
[edit | edit source]- Servicing Manual for ZX Microdrive, Interface 1 and Interface 2 (Thorn EMI Datatech for Sinclair Research, October 1985): Interface 2 description, circuit diagram (Fig. 1.4), disassembly, test, fault finding and parts list.
- The two-sided instruction card is scanned at Paul Farrow's ZX Interface 2 Resource Centre.[5]
Related pages
[edit | edit source]- Sinclair ZX Interface 1
- Sinclair ZX Printer
- Sinclair ZX Spectrum
- Sinclair ZX Spectrum +2, whose joystick ports use a related Amstrad chip
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 "Sinclair Interface II", reports from Sinclair User, December 1983, and Personal Computer News, October 1983, transcribed at World of Spectrum, "Hardware Feature #6" (retrieved 2026-10-19). Launched at the end of September 1983 for £19.95, by mail order at first; cartridges at £14.95; two joystick sockets for nine-way D joysticks reading the number keys; no built-in software, only a custom chip for the joystick ports; the cartridge socket with no paging, so cartridges replace the 16K BASIC ROM; cartridges fitted with the power off, then auto-start; the rear connector works with the ZX Printer only.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Thorn (EMI) Datatech Ltd for Sinclair Research Ltd, Servicing Manual for ZX Microdrive, Interface 1 and Interface 2, October 1985 (File:Sinclair ZX Microdrive, Interface 1 and Interface 2 Servicing Manual (Thorn EMI Datatech, 1985).pdf). Section 1 paras. 3.1 to 3.4 (description, ROMCS2, the joystick socket table), p. 1.8; Fig. 1.4 (circuit diagram); Section 2 para. 4 (disassembly: four cross-head screws), p. 2.2; Section 3 para. 4.1 (functional test with a ROM cartridge such as Space Raiders and two joysticks), p. 3.3; Section 4 para. 2.4 ("No problems have to date arisen with this unit"), para. 3.2 (short-circuit checks at the Spectrum connector, +5 V on 3b and +9 V on 4b against 0 V on 6b), para. 3.5 (fault finding: replace IC1; printer faults are discontinuity in the through connections), para. 4.1(b) (use the correct tools to change the plug-in IC), pp. 4.4–4.8; Table 5.7 (parts list: IC1 "MCE HT62001", SK1 28-way and SK2 15-way edge connectors, SK3 and SK4 9-way D connectors, Canton-Hill case parts, four 2.9 mm × 13 mm screws), p. 5.6.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Paul Farrow, "ZX Interface 2" pages (Introduction, Appearance, Circuitry, Limitations), ZX Interface 2 Resource Centre (retrieved 2026-10-19). Retail price £19.95, order code 8501, cartridges £14.95 and later £9.95; 116 × 71 × 30 mm; pop-out covers over the joystick sockets and a hinged cartridge flap; the through connector narrower than the Spectrum's and meant for the ZX Printer; a single custom chip for the joysticks; the cartridge plugging /ROMCS to +5 V to disable the Spectrum ROM; gold-plated contacts; no /RD or /WR at the slot; at least two board issues; a photograph of the top of the board, with the chip marked MT62001 and MCE 8344; no protection against inserting or removing cartridges with the power on.
- ↑ "ZX Spectrum Models", Spectrum for Everyone (retrieved 2026-10-19). The grey +2's joystick ports driven by an Amstrad 40057, essentially the MT62001 used in the ZX Interface 2.
- ↑ 5.0 5.1 5.2 5.3 5.4 Sinclair Research, ZX Interface 2 Manual, folded card, scanned at Paul Farrow's ZX Interface 2 Resource Centre, "Manual" (retrieved 2026-10-19). Connect all peripherals before switching on; the Interface 2 accepts only the ZX Printer at its rear, with other peripherals between it and the Spectrum; the locating tab and slot; the power supply drives a Spectrum, Interface 1, Interface 2, ZX Printer and eight Microdrives; the joystick socket next to the dimple is joystick 1; joysticks can be plugged in with the computer on; cartridges inserted flat side and title towards the computer; "Never insert or remove ROM cartridges when the computer is switched on"; keys 1 to 5 for joystick 2 and 6 to 0 for joystick 1; IN 61438 and IN 63486 and their bits.
- ↑ 6.0 6.1 "ZX Interface 2", Wikipedia (retrieved 2026-10-19). Released September 1983; joystick ports mapped to keys and not compatible with Kempston; ten commercial cartridges; the through bus stripped to the ZX Printer's signals.