GW4404A is a 68-pin VRAM SIMM which provides Apple Macintosh computers with 256 kB of VRAM.
GW4404A is built with an ENIG gold-plated, 4-layer PCB, and only new parts are used to build the VRAM SIMMs. All units are tested extensively before shipment, and all SIMMs conform to 80 ns timing or better, ensuring compatibility with all Macintosh models which support 68-pin VRAM SIMMs.
GW4404A features solid power and ground planes. Particular attention was paid to signal integrity, ensuring reliable performance on the fastest machines. The address bus traces are run as asymmetric striplines shielded inside the SIMM PCB, reducing interference generated by large VRAM SIMM arrays such as on the Quadra 700. Ample separation is provided between the DQ and SDQ buses routed on the front-side of the board. Particular attention was paid to the edge-sensitive RAS, CAS, and SCLK signals. These are optimized for minimum length, with large spacing between these edge-sensitive signals and all other signals and buses.
GW4404A's design is fully open-source. The schematics and board layouts are all freely available for commercial and noncommercial use. To download the design files, visit the Garrett's Workshop GitHub page.
GW4404A is always built with 80ns or faster VRAM chips, ensuring compatibility with all Macintosh models. We also have 70ns SIMMs available for overlocking purposes.