Home - Features - Downloads - Schematics - I/O Registers - Memory Map - Leave a Message
A Spartan-3E FPGA implementation of the ZX-Badaloc Spectrum clone
This is the schematic of the prototype board shown in the pictures, while a PCB is under development. The final design will probably use all 8 signals available on each Jx Digilent's connector, while now the lower row is not used (because only one row of pins was available on the previous design, based on the xilinx board).
The board provides the following peripherals:
Allows connection to a real tape player/recorder or a pc's soundcard. The game loading shown in the photo in the main page is carried out using this circuit.
AY-3-8912 sound chip Integrator and Amplifier
Converts the sigma-delta DAC single-bit output into an analog signal, which is then amplified and provided on both a small speaker and an RCA connector.
The SD-Card is used to store full machine snapshots or to access IDEDOS filesystems by ResiDos. The same SPI signals are also used to access the 25MP16 flash memory module (where zx-spectrum and clone ROMs are stored).
Programmable Joystick Interface:
It provides both a Kempston-compatible joystick (using the first 5 inputs) and a fully programmable one. Any of the 16 inputs can be mapped to any key, using the sd-card's snapshot editor built into the bootrom or by user software. This makes this interface compatible with every program ever written.
Still not installed, by now is mapped to two switches on the board.
Tape and SD-Card schematic