; ; Unlike the normal MTX512 PAL, this logic doesn't care about I2H4L. ; ; Back in the day, the memory decode was done by a PAL14L4. ; Nowadays PALs are superseded by GALs, and PAL programmers are hard to find. ; A GAL16V8 has 20 pins and can emulate a PAL14L4. ; ; http://www.brouhaha.com/~eric/retrocomputing/mmi/palasm/opaljr21.zip ; is the Opal junior 2.1 tools, including EQN2JED.EXE. ; TopWin Ver 6.32 and a TOP853 programmer can be used to program the GAL. ; TITLE MTX with 16KB+8KB ROM and 64KB RAM PATTERN A REVISION 1.0 AUTHOR ANDY KEY COMPANY NYANGAU.ORG DATE 30/6/12 CHIP 2_64 GAL16V8 A13 A14 A15 P2 R1 R2 P1 MREQL RDL GND I2H4L P0 RELCPMH RAM NA15 CE64 CEA P3 R0 VCC EQUATIONS /CEA = /RELCPMH * /A15 * /A14 * /A13 * /MREQL * /RDL + /RELCPMH * /R2 * /R1 * /R0 * /A15 * /A14 * A13 * /MREQL * /RDL /CE64 = /RELCPMH * /R2 * /R1 * R0 * /A15 * /A14 * A13 * /MREQL * /RDL + /RELCPMH * R2 * R1 * R0 * /A15 * /A14 * A13 * /MREQL * /RDL /NA15 = /A15 + /RELCPMH * /P3 * /P2 * /P1 * P0 * A15 * /A14 /RAM = A15 * A14 * /MREQL + RELCPMH * /P3 * /P2 * /P1 * /P0 * /MREQL + /RELCPMH * /P3 * /P2 * /P1 * /P0 * /A15 * A14 * /MREQL + /RELCPMH * /P3 * /P2 * /P1 * A15 * /A14 * /MREQL