Cabriolet was the name given to the AlphaPC64 motherboard, a derivative of the EB-64+ (Evaluation Board, 64 bit) made by Digital Equipment Corporation in 1995. This was one in a long series of reference motherboards for the Alpha processor produced as an aid to OEMs in manufacturing their own Alpha motherboards. Although many operating systems will run on this board, it was intended as a reference design for systems running Windows NT (TM).
Lots of these boards (new, in the original box, with manuals) started turning up at computer shows and online auctions a few years ago at a fraction of their original price (around $200 US instead of $1500) making it seem like a good deal for someone who wanted to play around with a 64-bit workstation on a budget, but it isn't quite that simple. AT power supplies with 3.3V outputs can be difficult to find and usually cost around $100 US. Although the board is called a baby AT, the PS/2 ports for the keyboard and mouse can't be used in a standard AT case. I found that a ATX case with the backplate removed worked OK once the power supply was swapped out. 72-pin parity memory is now very scarce, and incredibly expensive when compared to DDR memory, and must be installed in banks of four matching SIMMs. At the time of this writing, the 128 MB of memory I have in my Cabriolet system are probably worth more than the motherboard and processor put together. The firmware has very limited support for SCSI controllers, so getting my BusLogic adapter to work using Linux required installing an old 100MB IDE hard drive with a system partition containing MILO in order to boot it. Overall, unless you have all of the required components to build a system around one of these motherboards, it is generally cheaper to buy a used Alpha system rather than one of these motherboard/processor kits.
Baby AT form factor
21064A (EV45) processor at 275 mHz
4 PCI slots (1 shared)
3 ISA slots (1 shared)
8 72-pin SIMM slots (2 banks of 4, parity, 512 MB max., 70ns or faster)
512KB to 8MB L3 cache (requires 2 static RAM SIMMs, 15ns or faster)
1 parallel port
2 serial ports
PS/2 keyboard and mouse ports
1 debug port
1 IDE controller
1 floppy controller
ARC, SRM and debug console firmware
Requires AT power supply with 3.3V connectors.