The Avanti family is Digital's first generation of 21064 and 21064A desktop workstations and small servers with PCI. ¹⁾

The Alpha XL 233 and 266 are close relatives, and some early XL machines are in fact Avantis. A true XL has a different motherboard, on which Avanti kernels and MILO images do not work correctly; it can be identified by its 82379AB PCI-to-ISA bridge, where Avanti systems have the 82378IB or 82378ZB. ^{2) 3)}

• DECchip 21064A at 266 MHz
• DECchip 21072-AA (APECS) core logic
• 2 MiB write-back secondary cache
• Memory controller with a 128-bit data bus to main memory and a 128-bit bus to the secondary cache, longword parity protected
• Expandable to 512 MiB of memory, added as options of four SIMMs each in 32, 64, 128, or 256 MiB sizes ⁴⁾
• 33 MHz PCI: one PCI-only slot, one shared PCI/ISA slot, and one half-size ISA-only slot
• PCI-based embedded SCSI-2 controller supporting seven peripherals, and a PCI-based Ethernet adapter
• Floppy disk controller supporting a floppy drive and one CD drive
• Keyboard and mouse ports, two serial ports, one enhanced bidirectional parallel port

The AlphaStation 200 takes "72-pin, 70ns, 36-bit PC-type SIMMs if they meet the standard specs"; the SIMMs Digital shipped in the system may be 33-bit parts that will not work in a PC. ⁵⁾

• DECchip 21064A, with a jumper pair (J7 and J32) setting the CPU clock rate
• DECchip 21072-AA core logic
• 2 MiB write-back secondary cache
• 128-bit data bus to main memory and a 128-bit bus to the secondary cache, longword parity protected
• Memory expandable to 256 MiB, 33 MHz PCI
• One PCI-only slot, one PCI/ISA slot, and one half-size ISA-only slot, on a riser card
• PCI-based embedded SCSI-2 controller for up to seven devices, a PCI Ethernet adapter, and a sound card
• Floppy disk controller supporting a floppy drive and one further drive, keyboard and mouse ports, two serial ports, one enhanced bidirectional parallel port

• Socketed DECchip 21064A with DECchip 21071-AA core logic
• 1 MiB write-back secondary cache
• Two PCI, one PCI/ISA combination, and one ISA-only slot on a riser card, PCI at 33.33 MHz
• Two banks of four SIMMs, expandable to 1 GiB "when 128-MB SIMMs are available"
• Twisted-pair Ethernet on the motherboard, with an optional media adapter unit for ThinWire, and onboard audio jacks
• A switchpack replaces the AlphaStation 250's SROM and boot jumpers: switches 1 and 2 select the SROM mini-console, booting the console image from floppy, or clearing the RTC and NVRAM ⁶⁾

The AlphaStation 255's onboard Ethernet is a 10 Mb/s 21040. ⁷⁾

• CPU on a daughtercard: the PB50C-BA module carries a 233 MHz DECchip 21064A (EV4S) with 16 KiB instruction and 16 KiB data caches, DECchip 21071-AA core logic, 512 KiB of direct-mapped writeback secondary cache, 1 MiB of flashROM holding the ARC and SRM consoles, PALcode, and diagnostics, a 64 KiB diagnostic ROM, 8 KiB of NVRAM, and an 8-bit diagnostic LED display ⁸⁾
• Six SIMM sockets on the motherboard, expandable to 192 MiB
• 32-bit PCI at 33 MHz: two PCI slots, three ISA slots, and one combination PCI/ISA slot
• SCSI-2 controller with internal and external buses for up to seven devices
• Floppy disk controller supporting two floppy drives or one floppy and one tape drive, keyboard and mouse ports, two serial ports, one enhanced bidirectional parallel port
• Three 5.25-inch half-height bays, one hidden 3.5-inch half-height bay, and one 3.5-inch diskette drive, on a 300 W power supply

Digital also sold the AlphaStation 400's boards to OEMs as the AXPpci 233XL module set, the same modules used in the AlphaStation 400 4/233. ⁹⁾

• Early units have both the ARC and SRM consoles; later units have only one, and the other can be loaded from the firmware CD with update ARC or update SRM at the update utility's Apu→ prompt. ¹⁰⁾
• The AlphaStation 200 and 255 need different firmware images; flashing the 255 image into a 200 leaves its ARC console in a loop. On the AlphaStation 200, jumper J2 forces a firmware boot from floppy for recovery. ¹¹⁾
• On the AlphaStation 255, clearing the NVRAM with the configuration switches sets console to serial, so power-up messages go to COM1 and the graphics head shows only a blinking cursor. ¹²⁾

Linux 6.9 was the last version to support the Avanti systems, with CONFIG_ALPHA_AVANTI_CH; Linux 6.10 removed support for processors older than the EV56 (21164A). ¹³⁾ They boot from SRM with aboot. To MILO and the kernel, the AlphaStation 200 is identical to the other Avanti systems, although its motherboard does not use a CPU daughtercard. ¹⁴⁾

• MILO must not be written to flash on Avanti systems, which do not support it. ¹⁵⁾ Booting from SRM works cleanly. ¹⁶⁾
• The built-in 21040 and 21041 Ethernet controllers on the AlphaStation 200, 250, 255, and AlphaServer 300 do not work reliably with the de2104x driver. The same source suggested the de4x5 driver instead, ¹⁷⁾ but Linux 5.19 removed de4x5, leaving de2104x as the only driver for these chips. ¹⁸⁾
• The AlphaStation 200 and 400 have an onboard NCR 53C810 fast SCSI-2 controller, and the AlphaStation 200 a DECchip 21040 Ethernet controller on its riser card; ¹⁹⁾ the 53C810 uses the sym53c8xx driver. ²⁰⁾
• Digital offered an upgrade from the AlphaStation 255 to an AlphaStation 500 in the same enclosure; ²¹⁾ of the AlphaStation 500 models, only the 500/400 and 500/500 run current kernels.
• For a serial console on COM1, see Using the SRM Console: Serial console.
• S3 Trio64 cards are unreliable, particularly in the AlphaStation 200 and 400 (see Other Hardware).

Digital announced the AlphaStation 200 4/166 and 4/233 and the AlphaStation 400 4/233 on 3 November 1994, as the PCI/ISA systems that would replace its low and mid-range TURBOchannel DEC 3000 workstations. The 200 is a slimline desktop with three slots and four bays; the 400 is a mini tower with six slots and five bays. ^{22) 23)} The two differ in how they are upgraded: the AlphaStation 200 was to be upgraded by "a user-installable chip replacement", the AlphaStation 400 "via future CPU daughter card replacement". ^{24) 25)}

The AlphaStation 200 4/100 followed on 2 March 1995 as an entry-level desktop, ^{26) 27)} together with the AlphaServer 400 4/166, a 166 MHz uniprocessor server in the mini tower enclosure, taking up to 192 MiB of SIMM memory. ²⁸⁾

Digital announced the AlphaStation 250 4/266 on 3 April 1995. ²⁹⁾

The AlphaStation 255/233 and 255/300 followed on 8 March 1996, and could be upgraded to an AlphaStation 500 within the same enclosure. ³⁰⁾