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The Digital Semiconductor 21164 Alpha Microprocessor Evaluation Board (EB164) is an evaluation and development board for systems based on the 21164 microprocessor and the 21171 core logic chipset.

• 266 MHz 21164 CPU (also supports 300 MHz and 333 MHz) ¹⁾
• 21171 chipset (1x 21171-CA CIA, 4x 21171-BA data switches)
• 2, 4, or 8 MiB L3 Bcache on cache SIMMs, 6 ns to 15 ns SRAMs
• 8x 36-bit SIMMs (32 data bits, 4 check bits) in one bank, supports 32 MiB to 512 MiB of DRAM (70 ns or faster), 256-bit data bus
• PCI bus running at 25 MHz to 33 MHz
• 3x PCI slots (1x 64-bit, 2x 32-bit) plus 1x shared 64-bit PCI/ISA slot
• 2x ISA slots plus 1x shared ISA/PCI slot
• Intel 82378ZB PCI-to-ISA bridge
• National 87312 combination controller: IDE, diskette, 2x serial ports, parallel port
• Intel 8242 keyboard and mouse controller
• Dallas Semiconductor DS1287 time-of-year clock
• 1 MiB flash ROM containing the debug monitor and Windows NT ARC firmware
• Standard full-size PC AT board, 33.15 cm x 30.73 cm (13.05 in x 12.10 in) ²⁾

The EB164 supports only the 21164 (EV5), not the 21164A (EV56). The fastest CPU used was 333 MHz; changing CPU speed also requires a clock oscillator of the matching frequency. ³⁾

Both Bcache SIMM connectors must be populated. ⁴⁾ Cache SIMMs built with 128Kx8 SRAMs give 2 MiB, and SIMMs with 512Kx8 SRAMs give 4 or 8 MiB. The board was supplied with two 2 MiB, 10 ns Digital cache SIMMs, part number 21A04-M1. Main memory takes 70 ns, 5 V, 72-pin SIMMs organized as n x 36, from 1M x 36 to 16M x 36. ⁵⁾

In addition to the ARC console, an SRM console is available, and it is the preferred console for Linux. ⁶⁾ Only SRM reports correctable ECC memory errors; the EBSDK PALcode used by MILO does not. ⁷⁾

The last SRM release for the EB164 is V4.8. ⁸⁾ It does not support newer PCI-to-PCI bridges such as the DECchip 21154, so cards using them do not work from SRM, although they work with ARC and MILO. ⁹⁾

Linux 6.9 was the last version to support the EB164; Linux 6.10 removed support for processors older than the EV56 (21164A). ¹⁰⁾ Kernels up to 6.9 support it with CONFIG_ALPHA_EB164 or a generic kernel, booted from SRM with aboot.

The onboard IDE interface is part of the National PC87312 Super I/O chip, not a CMD646, which first appeared on the AlphaPC 164. No Linux driver was written to use more than PIO modes on it. ¹¹⁾

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. ¹²⁾
• Serial ports: 8250, at the standard PC addresses listed in the Alpha serial port table. ¹³⁾
• Parallel port: parport_pc; floppy: floppy; keyboard and mouse: i8042. ^{14) 15) 16)}

• Serial ROM and memory above 64 MiB: early boards with SROM revision "DAF2" are unstable with more than 64 MiB of memory. ^{17) 18)} The SROM (U12, a socketed Xilinx serial ROM holding the memory initialization code) cannot be reflashed in place. ¹⁹⁾ Digital supplied replacement SROMs labeled "3EEF" that fix the problem. ^{20) 21)} With an old SROM, limiting memory with MILO's setenv MEMORY_SIZE 63 makes the system stable. ²²⁾
• Clock battery: the Dallas DS1287 time-of-year clock contains a sealed lithium cell that keeps the clock and its 50 bytes of RAM running without power, ²³⁾ 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.

• Carrera and Microway built systems based on the EB164. ²⁴⁾
• The Aspen Timberline is Aspen's own design, essentially an EB164 with a PCI-to-PCI bridge providing seven PCI slots. ²⁵⁾ Aspen named the EB164 as the closest Digital equivalent of both the Timberline and its Summit system. ²⁶⁾