The recently updated ‘Interface 1bis’ is the only ZX Spectrum expansion device that features local storage, of up to 128 GB, subdivided in logical drives of 32 MB, on one micro SD card. It also features:
- Remote storage, of unlimited size, on a server machine, connected via a full-speed USB port.
- Kempston joystick port.
- PS/2 mouse port producing Kempston mouse or Kempston joystick output.
- Ethernet connectivity ready, by means of an optional, third party, add-on module.
- 100% software compatibility to the original ‘ZX Interface 1’ of Sinclair Research Ltd. in respect of ‘Microdrive’ storage operations, both at BASIC command and ‘hook code’ level.
- Enhanced ‘Extended BASIC’ with comprehensive random-access file handling capabilities and full emulator (.TAP and .Z80) files support.
The IF1bis has certain special features, not encountered on comparable devices:
- The non-volatile SRAM is protected by an adjustable, high precision, voltage supervisor IC.
- The control push-button is de-bounced and multiplexed using a dedicated microcontroller, which generates clean, digitally timed, RESET and NMI signals.
- The /ROMCS line is driven not through transistors, but a fast 3-state buffer, to ensure fail-safe memory paging.
- The joystick connector is mounted, perfectly rigid, on metal posts.Unlike most ZX Spectrum add-ons, the IF1bis does not perform hardware trapping and can therefore function even if the host machine’s CPU has a faulty /M1 line.