Zenith Data Systems 85-3017-1 8-Bit CPU Board 053084 ISA Vintage Z-100 1984

Zenith Data Systems 85-3017-1 8-Bit CPU Board 053084 ISA Vintage Z-100 1984

The Zenith Data Systems 85-3017-1 is an 8-bit ISA CPU board produced by Zenith Data Systems, a major American personal computer manufacturer of the 1980s. Marked with assembly number 053084 and sub-number 3585 on the PCB silkscreen, this full-length ISA card served as the central processor board in Zenith's Z-100 series computers. It features a rear bracket with a DIN connector for system interfacing and carries a dense population of through-hole TTL logic ICs, ROM sockets, and DIP configuration switches across the full length of the board.

Specifications & What's Included

• Manufacturer: Zenith Data Systems
• Part Number: 85-3017-1
• Assembly Number: 053084
• Sub-Number: 3585 (silkscreen)
• Type: 8-bit ISA CPU board
• Bus Interface: ISA (8-bit), full-length card
• Rear Bracket Connector: Single DIN connector
• Notable ICs visible: Intel L5503 (U230), 74LS138N (U204), 74LS27N (U205, U229), SN74ALS32N (U203), 5KK8528 (U205), 5KK8549 series logic
• ROM sockets: ROM1 and ROM2 positions populated (visible on board)
• DIP switches: SW1 and SW2 present for configuration
• RDY indicator: Red LED (CR206) on board edge
• Oscillator: Y201 crystal/oscillator module present
• Compatible with: Zenith Data Systems Z-100 series
• Vintage: Circa 1984
• Board only — no cables or accessories included

Applications

The Zenith Data Systems Z-100 was a dual-processor personal computer introduced in the early 1980s, capable of running both CP/M-85 and MS-DOS operating systems — a notable feature for its era that gave it broad software compatibility. The Z-100 series used a modular card architecture, and the 85-3017-1 CPU board was the heart of that system, housing the main processor, ROM firmware, and the logic circuitry that managed system operation. Zenith Data Systems was a significant player in the American business PC market of the early-to-mid 1980s, and the Z-100 was used in business, government, and educational settings. Today, boards like this are sought by collectors and vintage computing enthusiasts restoring Z-100 systems, as well as by researchers and historians documenting the early IBM-compatible PC ecosystem. Replacement CPU boards for the Z-100 are increasingly scarce, making even parts-condition examples useful as a source of hard-to-find components.