The Multia, or UDB ("Universal Desktop Box"), is a small desktop that Digital announced in December 1994, with a 21066 or 21066A CPU, onboard TGA graphics, a 21040 Ethernet controller, and one PCI slot. ^{1) 2)} The AXPpci 33 is a Baby-AT motherboard from Digital's Technical OEM group; both are based on the EB66 design and use the same CPUs and the same interrupt handling. ^{3) 4)}

The following describes the Multia; for the motherboard see AXPpci 33.

• 21066 or 21066A at 166 or 233 MHz, with the memory and PCI controllers on the CPU die ^{5) 6)}
• 64-bit memory bus, so SIMMs go in pairs rather than quartets, and parity SIMMs are required; parity cannot be disabled ^{7) 8)} EDO SIMMs do not work. ⁹⁾
• 24 MiB of memory as shipped, expandable to 256 MiB ^{10) 11)}
• Onboard TGA (21030) graphics and a 21040 Ethernet controller ¹²⁾; the Multia's BNC connector is handled differently from other 21040 implementations ¹³⁾
• Onboard SCSI, at IRQ 11, with an external SCSI port; riser cards came in several configurations ^{14) 15)}
• One PCI slot ¹⁶⁾
• Flash holding SRM in two chips and ARC in the third ¹⁷⁾; Digital provided no mechanism for updating the firmware ¹⁸⁾

Digital's service information separates the three Alpha models: the VX40 has a fixed 166 MHz CPU and a fixed 256 KiB cache, the VX41 has an upgradable 166 MHz CPU in a ZIF socket and upgradable 256 KiB cache, and the VX42 has an upgradable 233 MHz CPU and 512 KiB of cache. All ship with 24 MiB of memory and two PCMCIA slots; the floppy drive and the SCSI-2 connector are standard on the VX41 and VX42 and optional on the VX40. ¹⁹⁾

The system board jumpers differ between the VX40 and the later two. W9 on a VX40, or W12 on a VX41 or VX42, selects the mini console, and W7 or W11 forces a floppy boot fail safe load; W6 to W3 set the SRM graphics resolution. ²⁰⁾

Linux 6.9 was the last version to support the Multia and AXPpci 33; Linux 6.10 removed support for processors older than the EV56 (21164A), including the Noname kernel platform (CONFIG_ALPHA_NONAME). ²¹⁾ The same MILO image serves both machines. ²²⁾ MILO is normally started from ARC by linload.exe, which passes it the memory size; started from SRM, MILO assumes 24 MiB unless given the size, e.g. MEMORY_SIZE=32. ²³⁾

Linux 5.19 to 6.9 have no driver known to work with the Multia's onboard 21040 (Tulip): the de2104x driver was reported in 2006 to fail on machines with the original built-in 21040, including the Multia, ²⁴⁾ and the de4x5 driver that was recommended instead was removed in Linux 5.19. ²⁵⁾ The failure was reported again with the Debian 4.0 (etch) installer in 2007, when de2104x timed out stopping DMA on a Multia VX40. ²⁶⁾ Linux 2.6.35 fixed de2104x reading the MAC address from the onboard ROM on Alpha, ²⁷⁾ but no later report says whether the driver works on the Multia. de2104x is the only driver in current kernels for the 21040; the tulip driver does not handle it. ^{28) 29)}

The onboard SCSI controller is an NCR 53C8xx part: in 1996 the advice for Multia kernels was to select the NCR 53C8xx SCSI driver. ³⁰⁾ In Linux 6.9 that family is handled by sym53c8xx, ³¹⁾ and the onboard TGA (21030) graphics by tgafb. ³²⁾

SRM can also boot a Multia over the network with aboot; the 2007 report above booted the Debian installer with boot ewa0.0.0.8.0 -flags console=ttyS0, using the serial console. For serial console setup, see Using SRM. Current installers need more than the Multia's standard 24 MiB of memory: a 2016 report said that a 32 MiB Multia, tried a few years earlier, booted the installer but could not continue. ³³⁾

• Heat: the Multia's compact case causes overheating. ³⁴⁾
• Power connector: the 3.3 V wires of its power connector discolor and fail. ³⁵⁾

The 21066 integrates the memory controller, a PCI I/O controller, and an external cache controller on one die. ³⁶⁾ The 21066 is an EV4 core with half the on-chip L1 cache and an on-chip PCI interface, which together limit memory performance. ³⁷⁾

Digital did not sell the Multia as a general purpose workstation: the family was announced on 1 December 1994 as a "MultiClient Desktop", a network ready thin client with user applications and data held on central servers, shipping with Windows NT Workstation V3.5 factory installed. ³⁸⁾ In May 1995 Digital added a 233 MHz model at the top of the family, ³⁹⁾ and in November 1995 added Intel Pentium models alongside the Alpha ones. ⁴⁰⁾

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

• Whether the Multia's memory is parity or ECC
  • "Re: UDB RAM question", Jay Estabrook, axp-list, 23 Jul 1996: parity SIMMs are required and parity cannot be disabled.
  • Multia MultiClient Desktop Service Information, pp. 1-2: every model ships with "24 MB of ECC memory expandable to 128 MB".
• Multia maximum memory
  • Multia MultiClient Desktop Service Information, pp. 1-2: "24 MB of ECC memory expandable to 128 MB"
  • "Fact Sheet/Multia MultiClient Desktop", Digital Press and Analysts News, biz.digital.announce, 3 Nov 1994, gives 256 MiB, and "Multia install", Harmon Seaver, comp.os.linux.alpha, 3 Feb 2006, reports a Multia running with 256 MiB.