System 18 multi - 5) Pinning out the 315-5436 custom chip

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    • System 18 multi - 5) Pinning out the 315-5436 custom chip

      There's absolutely nothing about it online.
      It comes in a SDIP64 package (=Shrink DIP, with 0.07" pitch instead of 0.1").
      Signals names are those determined before for the romboard connectors.

      !RST->164Vcc
      !LWR->263<-ROM1
      D0_PRG->362<-!EXCS
      D1_PRG->461<-D3_PRG
      D2_PRG->560<-D4_PRG
      A13_FIX->659<-D5_PRG
      A14_FIX->758<-D6_PRG
      A15_FIX->857<-D7_PRG
      PRG_A19 (A4/A6)<-956NC
      PRG_A14 (A6)<-1055->SPR_A17
      PRG_A14 (A4)<-1154->SPR_A18
      PRG_A17 (A4/A6)<-1253->SPR_A19
      PRG_A18 (A4/A6)<-1352->SPR_CE3
      FIX_CE0<-1451->SPR_CE2
      FIX_A13<-1550->SPR_CE1
      Gnd1649->SPR_CE0
      FIX_A14<-1748Vcc
      FIX_A15<-1847->PROG_A19 (A5/A7)
      FIX_A16<-1946->PROG_A14 (A7)
      FIX_A17<-2045->PROG_A14 (A5)
      FIX_A18<-2144->PROG_A17 (A5/A7)
      FIX_A19<-2243->PROG_A18 (A5/A7)
      FIX_CE1<-2342->PROG_CE1
      D4 latch->2441<-PROG_RNG0
      A19_PRG->2540<-PROG_RNG2
      A18_PRG->2639<-PROG_RNG1
      A17_PRG->2738<-PROG_RNG3
      A16_PRG->2837<-A17_SPR
      A14_PRG->2936<-A18_SPR
      A3_PRG->3035<-A19_SPR
      A2_PRG->3134<-A0_PRG
      Vcc3233<-A1_PRG



      After all we can see there's no real magic here, relatively high pin count is to be expected:
      - 8 data lines inputs
      - 15 address lines inputs
      - 20 address lines outputs
      - 7 chip enable signals output
      - 4 power pins
      - 4 inputs to configure main program ROM space
      - 5 control signals inputs
      = 63

      DIP48 package is too small to fit everything so SDIP64 makes sense.
      Chip isn't used for security at all, it only performs pure logic operations, we'll see that in the next step.
      Looking for:
      - OutRun boardset even untested or not working
      - Sega Super Scaler hardware (Out Run, Model X, Model Y), even with faulty PCM chip



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