Sparrow 48K

The Sparrow 48K board (formerly known as Sparrow LITE) was developed as a spare part for repairing dead ZX Spectrum/Spectrum+ computers.

Sparrow 48K requires original ULA chip (supported are most common versions - 5C112, 6C001E-6 and 6C001E-7). The board fits to original ZX Spectrum („rubber Speccy“) and ZX Spectrum+ cases.

Comparing to original ZX Spectrum boards, the Sparrow 48K contains these improvements:

• video output is now the Composite video, not RF modulated
• the video RAM is in single SRAM chip
• the main (32KB) RAM is also in (another) single SRAM chip
• the system ROM is in 128KB FlashROM chip from which is the 16KB ROM selected by DIP switch, so it is possible to have 8 different ROMs. FlashROM chips with greater capacity (256KB or 512KB) are supported as long as they have the same pinout - but only first 128KB is exploited.
• the /RESET signal is done by TL7705 watchdog chip, so it is clean, without oscillations
• the board contains pin header for connecting RESET button (in Spectrum+ cases) as well as on-board RESET button for experimenting with uncased board
• the glue logic is now realized by small CPLD chip from Altera, instead of 74LSxx chips in original Speccy
• the board contains protection against use of power supplies with wrong polarity
• the +5V power is now done by LM2596 regulator, producing much less heat than original 7805
• the -5V power is no longer used
• the +12V power is now needed only for the LM1889 video chip, and is done by small 1 Watt DC-DC Converter

More information

Upgrading older versions to Rev.4

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