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The Alpha 21066A Microprocessor Evaluation Board (EB66+) is a baby AT form factor evaluation and development board for systems based on the Alpha 21066A microprocessor.

• 21066A CPU running at up to 233 MHz; lower frequencies are available through onboard jumpers ¹⁾
• 1 MiB external backup cache (Bcache), can emulate 256 KiB or 512 KiB by jumper
• 6x 72-pin 36-bit SIMMs in three banks of identical pairs, supports 8 MiB to 384 MiB of ECC DRAM (70 ns or faster)
• PCI bus integrated into the 21066A, running at 33 MHz
• 4x PCI slots (one shared with ISA)
• 5x ISA slots (one shared with PCI)
• Intel 82378ZB PCI-to-ISA bridge
• National PC87312 combination controller: IDE, diskette, 2x serial ports, parallel port (all on onboard headers)
• Intel 8242 keyboard and mouse controller
• Dallas Semiconductor DS1287 time-of-year clock
• Serial ROM and flash ROM containing a debug monitor
• Baby AT board, 33.02 cm x 22.1 cm (13.0 in x 8.7 in) ²⁾

DEC distributed SRM consoles for the EB66 and EB66+, along with its other evaluation boards, as part of its evaluation board software development kit. ³⁾

Linux 6.9 was the last version to support the EB66+; Linux 6.10 removed support for processors older than the EV56 (21164A). ⁴⁾ Kernels up to 6.9 support it with CONFIG_ALPHA_EB66P or a generic kernel. ⁵⁾ The MILO image is named eb66p. ^{6) 7)} The board uses the same interrupt design as the AlphaPC 64 (Cabriolet). ⁸⁾ For the original EB66, see EB66.

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. ⁹⁾ No Linux driver was written to use more than PIO modes on the PC87312. ¹⁰⁾
• Serial ports: 8250, at the standard PC addresses listed in the Alpha serial port table. ¹¹⁾
• Parallel port: parport_pc; floppy: floppy; keyboard and mouse: i8042. ^{12) 13) 14)}

• Clock battery: the Dallas DS1287 time-of-year clock contains a sealed lithium cell that keeps the clock and its RAM running without power, ¹⁵⁾ 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.