The AlphaPC 164LX is an ATX form factor motherboard for the EV56 (21164A), released by Digital in 1997 and later also made by Samsung (see Firmware). ¹⁾

• 466, 533, or 600 MHz EV56 CPU ²⁾
• 2 or 4 MiB external L3 cache (Bcache)
• 21174-CA chipset
• 4x 168-pin DIMMs, supports up to 1 GiB of unbuffered ECC SDRAM
• 2x 33 MHz 64-bit PCI slots
• 2x 33 MHz 32-bit PCI slots
• 2x ISA slots
• CMD646 IDE on PCI
• Intel 82378ZB PCI-to-ISA bridge
• SMC FDC37C935 Super I/O controller
• Floppy disk controller
• PS/2 keyboard and mouse
• 2x RS-232
• 1x Parallel port
• MMJ SROM console port
• ATX board, 30.48 cm x 24.38 cm (12.0 in x 9.6 in) ³⁾

The board is configured with jumper blocks J27 and J28. ⁴⁾

J27 CF0 and CF4 to CF6 are reserved and left out.

The 164LX can be jumpered for 466, 533, or 600 MHz. ⁵⁾ The PCI bus runs at its maximum speed only when the CPU speed is a multiple of 66 MHz, which is true of all three standard 164LX speeds. ⁶⁾ 21164A CPUs taken from Personal Workstations work, but their heatsinks have no fan, since the fan is part of the workstation enclosure. ⁷⁾

Some CPUs run AlphaBIOS at 600 MHz but are unstable under SRM; running them at a lower speed avoids the problem. ⁸⁾

The 164LX requires unbuffered 168-pin SDRAM DIMMs with ECC (x72 organization), installed in pairs. ⁹⁾ Non-ECC DIMMs are not detected, and the board repeatedly sounds five beeps to indicate that no memory is present. ¹⁰⁾ Registered DIMMs do not work. ^{11) 12)}

The manuals list 512 MiB (4x 128 MiB) as the maximum, but 4x 256 MiB (1 GiB) has been reported to work reliably. ¹³⁾ The lower documented limit is attributed to a capacitance issue with 4x 256 MiB. ¹⁴⁾ 512 MiB DIMMs do not work ¹⁵⁾; SRM may report up to 2048 MiB, but the memory is not usable. ¹⁶⁾

Not every module that meets the specification works. The board reads the module's SPD data and rejects modules it does not recognize, so some PC133 and high-density modules fail. ^{17) 18)}

Memory reported to work with the 164LX (and by extension the AlphaPC 164SX, which also accepts non-ECC modules):

• Kingston KVR100X72C2/256 ¹⁹⁾
• Micron MT18LSDT1672G-10EC2 ²⁰⁾
• Micron MT18LSDT3272AG-10EB1
• Crucial CT16M72S4D8E (128 MiB) ²¹⁾
• Crucial CT32M72S4D7E (256 MiB) ²²⁾
• Crucial CT32M72S4D8E (256 MiB) ²³⁾

Memory reported not to work:

• Kingston KVR133X72C3/256, due to wrong layout ²⁴⁾
• Any 512 MiB DIMM, any registered DIMM, and any non-ECC DIMM (see above)

The 164LX is designed for an ATX soft-power supply, with the front-panel switch connected to the soft power header (J1). A machine using a hard-switched supply and no soft power connection may fail to power on after being unplugged. ²⁵⁾ A jumper across the power switch pins, together with the SRM setting auto_action boot, makes the machine power on and boot automatically after a power failure. ²⁶⁾

A 300 W supply is sufficient for a typical workstation ^{27) 28)}; faster CPUs with 4 MiB of cache or many disks need more. ²⁹⁾

The CPU fan connector uses a different pin order from PC fans. On the Alpha connector, pin 1 is +12 V, pin 2 is the tachometer signal, and pin 3 is ground; PC fans use ground, +12 V, and tachometer. ³⁰⁾ The pins in a PC fan's connector must be rearranged before use; a miswired fan can damage the fan, motherboard, or power supply, and the board does not start without a correctly connected fan. ³¹⁾ Even when rewired, some PC fans do not provide a tachometer signal the board accepts. ³²⁾

The original 164LX fan is a 60 mm Panasonic Panaflo (high-speed version). ³³⁾

The flash ROM holds only one console image at a time, either AlphaBIOS or SRM. ^{34) 35)} The final releases are SRM V5.8 ³⁶⁾ and AlphaBIOS 5.7. ³⁷⁾ SRM V5.8-1 runs on both Digital and Samsung boards. ³⁸⁾

Switching from AlphaBIOS to SRM is done by copying lx164srm.rom to a FAT-formatted floppy and flashing it with the upgrade utility in AlphaBIOS Setup. ³⁹⁾ The flash is write-protected unless pins 2 and 3 of J28 are jumpered together, which is the default. ⁴⁰⁾

The SMMTABLE.TXT file on the V7.3 firmware CD lists SRM 5.8 as the last version for the board but names no update file for it (the entry is [ARCHIVE]NOFILE.EXE). ⁴¹⁾ The api/LX directory of the alphalinux/firmware repository holds API's 164LX files: lx164srm.rom with fwupdate.exe, whose accompanying fwreadme.txt (12 Oct 1998) describes SRM V5.3-3, and AlphaBIOS 5.68-1 (LXbios_5.68-1.zip). ⁴²⁾ According to its history file, AlphaBIOS 5.68-1 supports both the 28F008SA and 28F008S5 flash chips and is the version evaluated by Samsung. ⁴³⁾

AlphaBIOS uses different keys on a serial console: Tab to move between menu items, Ctrl+B to enter setup (instead of F2), and Ctrl+U to save the operating system configuration (instead of F10). ⁴⁴⁾

The 164LX was manufactured by both Digital and Samsung. Digital boards use an Intel 28F008SA flash chip, while some Samsung boards use an Intel 28F008S5, which has a slightly different command set ⁴⁵⁾; the change was a part substitution during production. ⁴⁶⁾

• SRM V5.8 can boot from the onboard IDE controller. ⁴⁷⁾
• SRM V5.8 on the 164LX and 164SX is the only pre-EV6 SRM that supports Adaptec SCSI controllers. ⁴⁸⁾ Support is limited to the 2940UW and 39160; other models (2940U, 2940U2W, 29160, 3950) are not supported by SRM, although they work under Linux. ⁴⁹⁾
• The console's BIOS emulator can initialize many later PCI video cards that older Alpha consoles cannot, including the ATI Rage 128 and Radeon ⁵⁰⁾ (including the Radeon 9100 ⁵¹⁾), 3Dlabs Oxygen VX1 and Permedia 2, 3dfx Voodoo Banshee ⁵²⁾, and nVidia TNT2 (ELSA Gloria Synergy II). ⁵³⁾
• SRM does not need the pci_device_override workaround on the 164LX to accept unrecognized cards in the 64-bit PCI slots. ⁵⁴⁾

A jumper on the board starts the fail-safe booter, which sounds one, two, and then three beeps, then loads fwupdate.exe or AlphaBIOS from a FAT-formatted floppy so that the console can be reflashed. ^{55) 56)}

The fail-safe booter itself is stored in block 0 of the flash ROM. ⁵⁷⁾ If block 0 is overwritten (for example, by writing MILO there with the flash management utility), the jumper no longer helps, and restoring the booter requires either a debug SROM containing the mini-debugger or removing and reprogramming the flash chip. ^{58) 59)}

Switching from SRM back to AlphaBIOS on the 164LX and 164SX can fail. Running the AlphaBIOS update from SRM may hang when AlphaBIOS offers to initialize invalid NVRAM, leaving SRM in place. ⁶⁰⁾ A reported workaround is to start AlphaBIOS from floppy (with arc at the SRM prompt, or with the fail-safe booter), then flash it using the upgrade option of the AlphaBIOS copy running in memory. ⁶¹⁾ This may take several attempts. ⁶²⁾

The motherboard's password-clear jumper clears only the AlphaBIOS password. Clearing a forgotten SRM password requires erasing part of the flash ROM from the Debug Monitor. ⁶³⁾

• 4 beeps with "No valid header found in ROM; loading entire ROM": flash ROM contents are corrupt. ⁶⁴⁾
• 5 beeps, repeated: no usable memory is present (for example, non-ECC DIMMs). ⁶⁵⁾
• 6 beeps: checksum error when the image was read back from memory. ⁶⁶⁾

Current kernels support the AlphaPC 164LX with CONFIG_ALPHA_LX164 or a generic kernel; it boots from SRM with aboot. ⁶⁷⁾ A kernel built for the LX164 is slightly faster than a generic one. ⁶⁸⁾ The onboard CMD646 IDE controller uses the pata_cmd64x driver. ⁶⁹⁾

• The CPU corresponds to GCC's -mcpu=ev56; it has the BWX extension but not MVI. ^{70) 71)} The 21174 core logic supports byte and word access to I/O space, which the kernel enables. ⁷²⁾
• The boot message pci: failed valid tag invalid pte reload test (mcheck; workaround enabled) appears on every 164LX and is harmless: it reflects a known weakness of the 21174. ⁷³⁾

The SMC FDC37C935 Super I/O controller's devices use the standard PC drivers:

• Serial ports: 8250, at the standard PC addresses listed in the Alpha serial port table. ⁷⁴⁾
• Parallel port: parport_pc; floppy: floppy; keyboard and mouse: i8042. ^{75) 76) 77)}
• Clock: the Alpha platform code reads the time-of-year clock itself rather than using rtc-cmos. ⁷⁸⁾

• Clock battery: the DS1287-compatible time-of-year clock is backed up by a replaceable CR2032 coin cell at B1. ⁷⁹⁾ Console settings that do not survive a power cycle usually mean the cell is exhausted; see Systems: Common problems.

• Aspen Systems Durango II ⁸⁰⁾
• Highscreen Alpha 5000 ⁸¹⁾
• Transtec ⁸²⁾

The following sources conflict with each other or with the account given above. They are listed here for further investigation.

• Registered memory
  • "Re: PC164LX board in an ATX case?", Maurice Hilarius, axp-list, 4 Jul 2001: "RAM: PC100 Registered ECC (in pairs)."
  • "Re: Memory for LX164 Alpha's", Maurice Hilarius, axp-list, 18 Mar 2002: "You need SDRAM, PC100, ECC, Registered."
  • "memory for an LX164", Steven Moix, axp-list, 12 May 2005: "Registered will NOT work…"
• Maximum memory
  • AlphaPC 164LX Motherboard Technical Reference Manual: "The AlphaPC 164LX supports a maximum of 512MB of main memory."
  • "RE: Memory Issues on an 164LX", Maurice Hilarius, axp-list, 18 Jan 2002: "4 x 256MB works. We have built over 400 with that.."
  • "Re: Memory Issues on an 164LX", Greg Lindahl, axp-list, 18 Jan 2002: "According to Compaq, the manual said that because there's a capitance [sic]"
• Cache size and CPU speed
  • "RE: SX164 RAM - (current) state with 512MB dimms ?", Kurt Ludwig, axp-list, 4 Dec 2000: "You could also get an LX board w/ 8MB of on board cache through Microway."
  • "Re: PC164LX board in an ATX case?", Maurice Hilarius, axp-list, 4 Jul 2001: "And a 667 with 4MB cache likes more juice than that…"
  • The manuals list 2 or 4 MiB of cache and CPU speeds up to 600 MHz.