PVI-486AP4 © 1994 Asus
The PVI-486AP4 is a premium, late-generation 80486 workstation-grade Baby AT motherboard designed and manufactured by ASUS around 1994 to 1995. Built to deliver maximum storage flexibility and peripheral compatibility, the system board is driven by the highly regarded SiS 85C496 (Northbridge) and 85C497 (Southbridge) Green PCI/VLB core logic chipset. It features a 168-pin Socket 3 footprint backed by an adjustable onboard Voltage Regulator Module (VRM) to cleanly support both 5V and energy-efficient 3.3V processors, including late-model Intel 486DX4 and AMD Am5x86 microprocessors running on a 33 MHz Front-Side Bus (FSB). Its extensive expansion subsystem features three 32-bit PCI local slots, four 16-bit ISA slots, and a dedicated 32-bit VESA Local Bus (VLB) slot. System memory is managed through four 72-pin SIMM banks supporting Fast Page Mode (FPM) and Extended Data Out (EDO) DRAM, complemented by an on-board secondary L2 write-back static cache (SRAM) DIP array expandable up to 512 KB.
The High-End Workstation Focus: While the sibling SP3 layout conquered the consumer clone market, the AP4 revision was heavily marketed toward corporate environments requiring advanced multi-tasking capabilities. It featured an exceptionally clean layout around the SiS Southbridge to optimize simultaneous data transfers between the PCI slots and the on-board Enhanced IDE channels without triggering data packet collision or latency overhead.
Elite Voltage Tuning: The PVI-486AP4 includes a highly robust and detailed set of onboard voltage jumpers. This advanced power configuration design allowed early hardware technicians to fine-tune the delivery rails to precise decimals, ensuring that sensitive late-generation write-back enhanced 486 CPUs could run cool and remain perfectly stable under heavy, continuous compilation workloads.