Altos 9122X eISA Multidrop Controller /2 Card 615-23201-001 ISA Bus

Altos 9122X eISA Multidrop Controller /2 Card 615-23201-001 ISA Bus

The Altos 9122X eISA Multidrop Controller /2 is a full-length ISA expansion card designed for Altos multi-user server systems. It provides multidrop serial communications capability, allowing the host system to support multiple simultaneous terminal or device connections over a shared serial bus. The board carries the PCA designation 615-23201-001 and is silkscreened directly on the PCB.

Specifications & What's Included

• Manufacturer: Altos
• Model: 9122X
• Part Number (PCA): 615-23201-001
• Card type: eISA Multidrop Controller /2
• Bus interface: ISA / eISA (full-length card)
• Bracket connector: DB-25 female (single, bracket-mounted)
• Board populated with multiple DIP IC packages and DIP socket arrays
• Oscillator/crystal present on PCB (frequency not legible in photos)
• Board revision: REV (suffix character not clearly legible in photos)
• Card only — no cables, brackets beyond the installed one, or accessories included

Applications

Altos Computer Systems was a prominent maker of multi-user Unix-based servers and workstations during the 1980s and into the early 1990s, targeting small-to-medium business environments that needed multiple simultaneous terminal users on a single system. The 9122X series were Altos multi-user servers that relied on specialized expansion cards like this Multidrop Controller to extend their serial terminal connectivity beyond what the base I/O provided. Multidrop serial controllers of this type allowed a single card to drive several RS-232 terminals or serial devices in a party-line (multidrop) topology, which was the common architecture for character-based terminal networks of that era. This card dates from the late 1980s to early 1990s ISA-bus generation. Today these cards are primarily sought by collectors and technicians maintaining legacy Altos systems still in operation.