Cirkit serial interface

The Cirkit serial link was used for the Cirkit Prestel link

Reportedly, it did "flourish", but almost nothing else is known.

• Some information fragments are here: Cirkit.

(information from the documentation with the "Prestel Link" software.)

Prestel link hardware:

• 4Mhz clock from expansion bus is clock for 8251
• Chipset: uses 8251 UART
• I/O ports are:

FADF read/write data
FBDF read status/write control

• Note - Cirkit reportedly also made a "Twin-port" serial interface (which probably used other chipset)

• 

  Circuit board, etc.

• None such...?

• Fully compatible with the CPC464, CPC664 and CPC6128.
• Plugs into Disk Drive, through Bus Connector for Disk Drives and other peripherals.
  [Note: On the CPC 464, the "Expansion Port" was called "Floppy Port", this is probably what is meant by "into Disk Drive"]
  [Note: The photo in advert seems to be a fake. It looks like a 2x28 pin expansion for Sinclair Spectrum, re-badged as Amstrad Interface for the advert]
• Can be used to interface to other RS232 devices, such as Modems, Plotters and Printers.
• Baud rates supported 75/1200, 1200/1200 and 300/300
• INPUTS:- Data, one handshake - RS232 compatible
• OUTPUTS:- Data, one handshake - +5 volt positive going Works with all TTL level inputs and most RS232 devices.
• All interface features are software addressable, uses 8251 UART.
• Supplied with full RSX drivers, which may be used in your own programs.
• Not directly compatible with Amstrad CPM.
• Extensive documentation about interface and RSX's supplied on cassette.