The AlphaPC 64 (code name Cabriolet) is a motherboard released by Digital in 1995. ¹⁾ It was also sold as the Alpha PCI64-275 (part number EBP30-AN). ²⁾

The AlphaPC 64 was derived from the EB64+, and Linux treats it as a variant of that board, so the names Cabriolet, AlphaPC64, PCI64, and EB64+ are often used interchangeably. They are different boards, however: the AlphaPC 64 is a slightly modified baby AT board whose mounting holes are offset from the standard positions. ^{3) 4)}

• Alpha 21064A CPU at 200, 233, or 275 MHz in a ZIF socket ⁵⁾
• 512 KiB, 2 MiB, or 8 MiB external L2 cache on 2x cache SIMMs
• DECchip 21072 chipset (21071-CA cache/memory controller, 4x 21071-BA data path, 21071-DA PCI bridge)
• 8x 36-bit DRAM SIMMs in 2 banks, supports 16 MiB to 512 MiB with parity, 128-bit data path
• 4x 32-bit 33 MHz PCI slots and 3x ISA slots (6 total, 1 slot shared between PCI and ISA)
• Intel 82378ZB SIO PCI-to-ISA bridge
• National 87312 Super I/O controller providing floppy, IDE, 2x serial ports, and parallel port
• Intel 8242 PS/2 keyboard and mouse controller
• Dallas Semiconductor DS1287 time-of-year clock
• 1 MiB flash ROM containing Windows NT ARC firmware and debug monitor
• Baby AT board, 33.0 cm x 22.1 cm ⁶⁾

The keyboard and mouse connectors are placed together where an AT case normally has only the keyboard connector, so the opening in a standard AT case must be enlarged. ⁷⁾

The board takes 72-pin 36-bit true parity SIMMs, installed in banks of four. ^{8) 9)}

The L2 cache is built from two cache SIMMs, and both are required. The SIMMs available when the manual was written were 512 KiB with 15 ns SRAMs and 2 MiB with 12 ns SRAMs; the board also supports 8 MiB SIMMs. ¹⁰⁾

The AlphaPC 64 does not use a standard AT or ATX power supply. It requires an AT power supply with two additional 6-pin connectors (often labeled P9 to P12), each carrying three +3.3 V and three ground pins, in addition to the usual +5 V, +12 V, -5 V, and -12 V. ^{11) 12)} On the board, the +3.3 V connectors are J27 and J28. ¹³⁾

The flash ROM is large enough to hold both the ARC and SRM consoles at the same time, allowing Windows NT and Linux to be booted from ARC and Digital UNIX from SRM. ¹⁴⁾ Selecting Digital UNIX from the ARC "Machine Specific Setup" menu and power cycling switches to SRM; setting the SRM os_type variable to NT and power cycling switches back. ¹⁵⁾

• ARC: the last version is 4.49-7. It is updated with fwupdate.exe via "Install new firmware" in the firmware's Supplementary Menu. ^{16) 17)}
• SRM: the last version is 4.8 (V4.8-1, dated 20 Feb 1997). ^{18) 19)} SRM was originally available only as part of DEC's evaluation board software development kit, but in December 1999 Compaq made the image freely available. ^{20) 21)}
• MILO can be loaded from ARC with linload.exe, or by renaming the MILO image to fwupdate.exe and using the ARC firmware update option. ²²⁾ Flashing MILO can overwrite the SRM console. ²³⁾

Recovering from corrupted flash is difficult: unlike the UDB, there is no floppy-based fail-safe loader. ²⁴⁾

Linux 6.9 was the last version to support the AlphaPC 64; Linux 6.10 removed support for processors older than the EV56 (21164A). ²⁵⁾ Kernels up to 6.9 support it with CONFIG_ALPHA_CABRIOLET or a generic kernel. ²⁶⁾

Both SRM (with aboot) and ARC (with MILO) can boot Linux. ²⁷⁾ The MILO image is named cabrio or cabriolet; images for other boards do not work. ^{28) 29)}

In kernels up to 6.9, the onboard devices use these drivers:

• IDE (PC87312): the interface is not a PCI device, so it is handled by pata_legacy, which probes the legacy ports at 0x1F0 and 0x170 when no PCI controller claims them. ³⁰⁾ No Linux driver was written to use more than PIO modes on the PC87312. ³¹⁾
• Serial ports: 8250, at the standard PC addresses listed in the Alpha serial port table. ³²⁾
• Parallel port: parport_pc; floppy: floppy; keyboard and mouse: i8042. ^{33) 34) 35)}

• SCSI boot: the board has no onboard SCSI. SRM 4.8 boots only from NCR 53C810 and QLogic ISP1020 adapters, ³⁶⁾ and ARC from few SCSI adapters: Intraserver 3140U-N and 4140UE-N cards are reported to work, and the Diamond Fireport40, BusLogic BT958, and Adaptec 2940 not to. ^{37) 38)}
• Clock battery: the Dallas DS1287 time-of-year clock contains a sealed lithium cell that keeps the clock and its RAM running without power, ³⁹⁾ so the chip itself must be replaced once the cell is exhausted. For a replacement part, see AXPpci 33: Known issues. See also Systems: Common problems.