Interface 1bis for the Sinclair ZX Spectrum

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Умельцы из ЮАР продают сей девайс.

The ‘Interface 1bis’ is the only ZX Spectrum expansion device that features the combined functionality of:
- Local storage, of up to 128 GB, subdivided in logical drives of 32 MB, on one micro SD card (not included).
- 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.
- Full software compatibility to the original 'ZX Interface 1' of Sinclair Research Ltd. in respect of 'Microdrive' storage operations.
- Enhanced 'Extended BASIC' with comprehensive random-access file handling capabilities and emulator (.TAP and .Z80) files support.

Hardware
The key to its versatility is the distinctive architecture of the IF1bis, which offloads all peripheral I/O operations onto a microcontroller, connected directly to the system’s data bus. This simplifies the design to a great extent and in conjunction with a rationalized memory configuration, requiring just one 32KB non-volatile SRAM chip, adds considerable benefits like:
- Small PCB size, of under 0.5dm2, allowing a
- Zero desk foot-print, due to vertical mounting.
- Simple, two-layer, PCB layout with very short tracks, for reduced noise.
- Low power consumption: at under 75mA, the lowest among comparable devices
- Low bus load: unequalled at only 0.7µA data bus leakage and only 0.5µA plus 1 (one) standard CMOS load on the other lines.
- Improved peripheral device handling, as the microcontroller, with its multiple hardware timers and complex interrupt logic, is specialized and better equipped for this task than the ZX Spectrum’s CPU.
- Faster transfer between local and remote storage as it is performed directly by the microcontroller, via its USB and SPI ports, bypassing the ZX Spectrum.
- Simplified operating system, needing only one device driver: for the ‘Parallel Slave Port’ of the microcontroller, which in turn handles all low level peripheral control operations.
The IF1bis has certain special features, not encountered on comparable devices, as no compromise on robustness was made in the process of optimizing the cost:
- 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.
And last, but not least:
- The IF1bis does not perform hardware trapping and can therefore function even if the ZX Spectrum’s CPU has a faulty /M1 line.


Operating system
The ‘Interface 1bis’, as the name intends to suggest, is 100% software (backward-) compatible to the ‘ZX Interface 1’ of Sinclair Research, in respect of ‘Microdrive’ storage operations, both at BASIC command and ‘hook code’ level.
The ‘ZX Net’ and RS232 port communication functions of the original were not implemented as such, being considered impractical, given their limited functionality and peer-to-peer nature.
In their place, a remote file system for client-server networking over a USB port, was devised.
All file handling operations can equally be performed on any of the two implemented file systems:
- local, for the SD card (device“M”) and
- remote, for the file server (device “V”),
with the exception of FORMAT-ing the server’s hard drive, which is, for obvious reasons, impossible.
The main enhancements to the ‘extended BASIC’ of the original ‘ZX Interface 1’ are:
- The file size limit is 16 MB.
- Sequential access is not restricted to ‘PRINT’ files.
- Sequential access ‘M-channels’ can be selectively opened for input or output.
- Data in memory can be read, written or verified, through direct random access, to (or from) a specified position in a file, of any type, without the need to OPEN it.
- Random access ‘file handles’ can be used to more conveniently reference files and automatically keep track of their random access pointers.
- Both sequential access pointers of ‘M-channels’ and random access pointers of ‘file handles’ can be moved to any position.
- Full support for the following 'emulator file types': .TAP tapes images, .Z80 snapshots and .SCR screen dumps.
- Abbreviated syntax, allowing the omission of the ‘device type’ and ‘drive number’ fields in a statement, if they are the same as in the previous one.
The operating system of the ‘Interface 1bis’ has a very long development history, being written
18 years ago and since then constantly improved and adapted to new hardware configurations.
It is a mature, stable product, tailored to practical needs and offering arguably unrivalled functionality, speed and ease of use.

Кто что думает, это конкурент divIDE или нет? Возможностей с виду больше. Что-то не видел обсуждения на нашем форуме новой железяки.

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