Sinclair SIF is new communication interface for most models of Sinclair ZX Spectrum. Main purpose is dual RS 232 with hardware flow control. Infterface is populated with two 16C650 UARTs and CPLD XC9572 for addressing. PCB is using SMT components and vertical board mount allow pass through all bus signals for other devices (DivIDE, etc.)
First channel is wired to full RS232 transceiver (3x TX, 5x RX) to DB9 connector.
Second channel can be internally multiplexed with IrDA or place for embeded module with Wifi or Ethernet. For wifi and Ethernet are used ConnectOne modules and only one module could be placed to board.
CPLD on interface is providing follow services:
Addressing IO in 8 bit addres mode. Interface needs 8 ports and this ports could be moved in address range by solder pins on board
Select of port and interupt from UARTs monitoring
Interupt in IM2 mode with fix vector ($FF)
UARTs used on board have this features:
Automatic hardware flow control
Speed up tu 460800 baud (Uart1 is limited by RS232 transceiver to 250kbaud)
32 byte RX and TX FIFO