ATC-1425A © 199? A-Trend
The 1425A is a classic "Early PCI" motherboard. It was one of the first mass-produced boards to attempt the leap from the established VLB standard to the then-nascent PCI bus. It is a more rudimentary board than the B variant, often featuring less mature BIOS code and less flexible voltage regulation, which made it a challenge for the early 486DX4 and 5x86 upgrades.
Chipset: SiS 496 (North) / SiS 497 (South).
CPU Support: Socket 3 (primarily 5V support, with limited 3.3V compatibility via jumpers).
Expansion: 3 PCI slots and 4 ISA slots.
Memory: 72-pin SIMM sockets (though early revisions often had strict memory-matching requirements, meaning you had to fill banks in pairs with identical SIMMs).
Form Factor: Baby AT.
The Jumpers: The "A" revision is notorious for its "jumper spaghetti." To configure the bus speed and CPU voltage, you are looking at a dense cluster of jumpers located right behind the keyboard connector. It is a classic "read the manual or destroy your CPU" board.
VLB vs. PCI Confusion: When the ATC-1425A first hit the market, many users still wanted to use their old VLB graphics cards. While some SiS 496 boards included VLB slots, the 1425A focused entirely on PCI. This caused quite a stir in 1994, as many enthusiasts were forced to buy brand-new PCI graphics cards (like the early S3 Trio) just to get the system to boot.