Interface 1 Bis
The present project expands the ZX Spectrum 48K by providing it with mass storage and communication capabilities, through a device that can be built by any hobbyist from readily available components, and at the same time maintains as much software compatibility as possible with the original Sinclair Interface 1.
Its main features are:
- Operating system in RAM: The operating system resides in a 32 Kbytes SRAM, the lower half of which contains a slightly modified copy of the Spectrum ROM and the upper half, an IF1 ROM equivalent. The changes to the Spectrum ROM allow:
- the paging of the first 16 KBytes of memory to be done under software control rather than through hardware, as in the case of the original IF1,
- the integration of an ESC/P2 printer driver in the Spectrum BASIC,
- the handling of 'tape files' (.TAP), by trapping the calls to the SA-BYTES and LD-BYTES routines,
- creating snapshot files (.Z80), through a modified NMI routine,
- fixing known Spectrum ROM bugs.
- RAM disk: Up to three 128 Kbytes RAM disks.
- Hard disk interface: Can drive two IDE devices in PIO mode. The physical disks are formatted in up to 251 logical disks of 32 Mbytes, giving a total storage capacity of almost 8 Gbytes.
- Parallel printer port: Full uni-directional Centronics printer port.
- PC connectivity: The parallel port can also be used to connect the Spectrum through a 'Laplink' cable to a PC running an appropriate server application, by which a printer attached to the PC can be shared and the PC's drives can be accessed as a 'network disk'.
- Standard Kempston joystick interface.
- RESET and NMI buttons.
This device will not work with ZX128. The IDE interface you can build
just rewiring YAMOD.ATBUS.
Files for download
- image001.jpg 44.1kB (2004-10-12 03:40)
- Front view, interface in the middle. From left: power supply, harddisk, monitor and interface case moved up.
- image003.jpg 64.7kB (2004-10-12 03:41)
- Another top-angle view.
- image002.jpg 63.3kB (2004-10-12 03:41)
- Uncased side view.
- i1rom.zip 56.2kB (2001-12-02 00:32)
- IF1 substitute ROM source code.
- zxrom.zip 29.0kB (2001-12-02 00:19)
- Modified Spectrum BASIC ROM source code.
- zxs.zip 8.6kB (2001-12-01 23:00)
- PC server application source code.
- if1bis.zip 13.9kB (2001-10-15 12:16)
- Detailed technical documentation.
- schematic.zip 89.0kB (2001-10-03 00:46)
- The hardware schematics.
Links to other pages
- Author's page.
- YAMOD.ATBUS 8bit IDE
- The fastest 8bit universal IDE multiplexer for YABUS. Includes RTC type DS 1287, DS 12887 or MC 146818.