Soyo SY-015G 386DX reverse engineering by RayeR, 1.2.2026 MX83C305FC GND: 1, 21, 25, 40, 58, 81, 102, 120, 151, 160 MX83C305FC VCC: 18, 60, 103, 109, 152 MX83C306FC GND: 1, 40, 52, 68, 80, 94, 101, 120, 137, 138, 150, 160 MX83C306FC VCC: 21, 69, 93, 100, 121, 149 MX83C305 MX83C306 Am386DX U7(74F244) U8(74F244) U6(74F244) U5(74F245) 160 - GND 159 - ISA.A6 x x 158 - ISA.A7 x x 157 - ISA.A8 x x 156 - ISA.A9 x x 155 - KBC.CS# x x 154 x x 153 x x 152 - VCC 151 - GND 150 - ROM.CS# 149 x x 148 x x 147 x x 146 x x 145 - ISA.D0# 139 - U5.11 - B8 9 - A8 144 - ISA.D1# 140 - U5.12 - B7 8 - A7 143 - ISA.D2# 141 - U5.13 - B6 7 - A6 142 - ISA.D3# 142 - U5.14 - B5 6 - A5 141 - ISA.D4# 143 - U5.15 - B4 5 - A4 140 - ISA.D5# 144 - U5.16 - B3 4 - A3 139 - ISA.D6# 145 - U5.17 - B2 3 - A2 138 - ISA.D7# 146 - U5.18 - B1 - broken PCB trace off ISA slot 9 A2 pin! 2 - A1 137 - ISA.D7:0-DRV-DIR 1 - DIR 136 x x 8 - 1A4 135 x x 6 - 1A3 134 x x 4 - 1A2 133 x x 2 - 1A1 132 x x 8 - 1A4 131 x x 6 - 1A3 130 x x 4 - 1A2 129 x x 2 - 1A1 128 x x 11 - 2A1 127 x x 13 - 2A2 126 x x 15 - 2A3 125 x x 15 - 2A3 124 x x 17 - 2A4 123 x x 13 - 2A2 122 x x 11 - 2A1 121 x x 2,4,6,8 - 1A1-4 120 - GND 119 x x 118 x x 117 x x 116 x x 115 13 x 114 14 x 113 x x 112 - ISA.D7:0-DRV-E# x x 19 - E# 111 2 x 110 15 x 109 - VCC 108 16 29 - BS16# 107 17 x 106 18 x 105 x x 104 20 x 103 - VCC 102 - GND 101 39 x 100 22 x 99 23 x 98 24 x 97 x x 96 x 28 - HOLD 95 x x 94 25 x 93 x 45 - RESET 92 - ISA.A20 x x 91 x 8 - HLDA 90 - A2 29 67 - A2 89 - A3 30 68 - A3 88 - A4 31 69 - A4 87 - A5 32 70 - A5 86 - A6 33 71 - A6 85 - A7 34 72 - A7 84 - A8 35 74 - A8 83 - A9 36 75 - A9 82 - A10 37 76 - A10 81 - GND 80 - A11 38 77 - A11 79 - A12 x 78 - A12 78 44 31 - BE0# 77 43 32 - BE1# 76 42 33 - BE2# 75 41 38 - BE3# 74 26 43 - W/R# 73 x 41 - D/C# 72 28 40 - M/IO# 71 x 26 - READY# 70 x 27 - ADS# 69 - A13 x 79 - A13 68 - A14 x 81 - A14 67 - A15 x 82 - A15 66 - A16 x 84 - A16 65 - A17 x 86 - A17 64 - A18 x 87 - A18 63 - A19 x 88 - A19 62 - CPU.A20 x 89 - A20 61 x x 60 - VCC 59 x x 58 - GND 57 x x 56 - A21 x 93 - A21 55 - A22 x 94 - A22 54 - A23 x 95 - A23 53 - A24 x 96 - A24 52 - A25 x 97 - A25 51 - A31 x 104 - A31 50 x 50 - PEREQ 49 x 47 - ERROR# 48 x x 47 134 x 46 x x 45 x x 44 x x 43 x x 42 x x 41 x x 40 - GND 31 - ROM.OE# 29 - KBC.RD# x x 28 - KBC.WR# x x 18 - VCC 7 - ISA.A0 x x 6 - ISA.A1 x x 5 - ISA.A2, KBC x x 4 - ISA.A3 x x 3 - ISA.A4 x x 2 - ISA.A5 x x 1 - GND 8 - ISA.I/O_CH_CK# U14 KBC 8042 U15(74LS05) U20(74F04) U17(74LS00) 1 - KBCLK, 1k pull-up RP8 2 - 1Y O.C. 2 - X1 (7,14MHz) 6 - 3Y 3 - X2 (7,14MHz) 5 - 3A 4 - RESET 11 - 5A 12 - 6Y 5 - SS, VCC +5V 6 - CS# to pin 155 of MX83C305 7 - EA, GND 8 - RD# to pin 29 of MX83C305 9 - A0 to pin 5 of MX83C305 (ISA.A2) 10 - WR# to pin 28 of MX83C305 11 - SYNC x 12 - D0 (common with ROM & RTC) 13 - D1 (common with ROM & RTC) 14 - D2 (common with ROM & RTC) 15 - D3 (common with ROM & RTC) 16 - D4 (common with ROM & RTC) 17 - D5 (common with ROM & RTC) 18 - D6 (common with ROM & RTC) 19 - D7 (common with ROM & RTC) 20 - GND 21 - P20 to pin 153 of MX83C305 22 - P21 60 (NC on PQFP, GND on PGA J13) 23 - P22 x 24 - P23 x 25 - PROG +5V 26 - VDD +5V 27 - P10 x 28 - P11 x 29 - P12 x 30 - P13 9 - 3A 31 - P14 x 32 - P15 x 33 - P16 JP3 to GND 34 - P17 J17 KEYLOCK.4 35 - P24 to pin 123 of MX83C306 (IRQ1) 36 - P25 x 37 - P26 1 - 1A 38 - P27 3 - 2A 39 - KBDATA, 1k pull-up RP8 12 - 6Y O.C. 40 - VCC +5V 13 - 6A 4 - 2Y 9 - 4A 8 - 4Y