The PSG distortion problems have been fixed with this revision. It is essentially a much improved VA1.8, using the 315-5684 amplifier first featured on the VA2 and VA2.3 revision motherboards. This is the first Model 2 system to utilize a smaller motherboard footprint.
Doesn't include the YM2612.ģ15-5685 ASICs have faulty shadow/highlight support. The 315-5786 ASIC does not have this problem.Īs with the VA2, a series resistor at R31 causes PSG distortion. The 315-5685 ASIC has slightly broken shadow/highlight support, where the shadow/highlight effects are offset to the right by one pixel onscreen. Most VA2.3s use the 315-5685 main ASIC, but some systems may use the 315-5786 alternatively. This revision integrates the 74HC14 hex-inverting Schmitt trigger, and moves some components around. I/O, Bus arbiter, VDP, TMSSVDP and IO chip all-in-one.
The BA10358 op-amplifier serves as the FM pre-amplifier.Ī series resistor at R31 is responsible for the distorted PSG sound reported on these models. A small daughterboard with a 74HC14 hex-inverting schmitt trigger is typically present, its function is unknown. It is also the first Model 2 to feature the 315-5684 sound network/headphones amplifier. This revision, along with the VA2.3, uses a discrete YM2612 FM synthesizer. It even shares the same PCB prefix (PC).ĬMOS 256K (32K x 8) High Speed Pseudo-Static RAMĦ5,536-WORDx4-bit Multiport CMOS video ram The VA7 is almost a Genesis 2 PCB in a Genesis 1 case. VA3 837-7071 List of IC'sĢ56K (64K x 4-bit) VRAM & dual-port graphics buffer CMOS 256K (32K x 8-bit) Pseudo-SRAM, 12nsĢ56K (64K x 4-bit) VRAM & Dual-Port Graphics Bufferįrequency modulation synthesizer (Sound Chip)
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