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Revised 2 slot board with the second generation chipset.


todo: formatting, maybe pics


todo. Pair of NEO-257 on far left of board used for this? 32 bits per slot multiplexed to NEO-ZMC2?


FIXD0~FIXD7 is multiplexed from each from by NEO-257 @ J9. Same one is used for Z80 D0~D7 for cart M1 access.

NEO-257 CHA slot #1
A0(4) FIXD0(B39)
A1(6) FIXD1(B40)
A2(13) FIXD2(B41)
A3(15) FIXD3(B42)
A4(19) FIXD4(B43)
A5(21) FIXD5(B44)
A6(29) FIXD6(B45)
A7(31) FIXD7(B46)
NEO-257 CHA slot #2
B0(5) FIXD0(B39)
B1(7) FIXD1(B40)
B2(14) FIXD2(B41)
B3(16) FIXD3(B42)
B4(20) FIXD4(B43)
B5(22) FIXD5(B44)
B6(30) FIXD6(B45)
B7(32) FIXD7(B46)

Selected FIX data is output to NEO-B1 from Y0~Y7.

NEO-257 NEO-B1
Y0(8) FIXD0(131)
Y1(9) FIXD1(132)
Y2(11) FIXD2(133)
Y3(12) FIXD3(134)
Y4(23) FIXD4(135)
Y5(24) FIXD5(136)
Y6(27) FIXD6(137)
Y7(28) FIXD7(138)

The 257 seems to have common enable/select lines. See M ROM section for those as cart M ROM/S ROM are always enabled together.

V ROM / YM2610 access

todo. NEO-E0 for address outputs only, some NEO-G0 for the databuses?


YM2610 RAD0~RAD7 goes through NEO-G0 @ K9 and out to each cart slot through a separate set of pins. (NEO-G0 needs a proper set of pin names).

NEO-G0 YM2610
(2) RAD0(17)
(3) RAD1(16)
(4) RAD2(15)
(5) RAD3(14)
(15) RAD4(13)
(16) RAD5(12)
(17) RAD6(11)
(18) RAD7(10)
NEO-G0 PROG slot #1
(6) SDRAD0(B49)
(7) SDRAD1(B50)
(8) SDRAD2(B51)
(9) SDRAD3(B52)
(11) SDRAD4(B53)
(12) SDRAD5(B54)
(13) SDRAD6(B55)
(14) SDRAD7(B56)
NEO-G0 PROG slot #2
(62) SDRAD0(B49)
(63) SDRAD1(B50)
(64) SDRAD2(B51)
(1) SDRAD3(B52)
(21) SDRAD4(B53)
(22) SDRAD5(B54)
(23) SDRAD6(B55)
(24) SDRAD7(B56)

Control signals and other address lines buffered through NEO-E0 to both cart slots @ F8.

NEO-E0 YM2610
A7(16) RA8(23)
A8(17) RA9(22)
A9(18) RA20(35)
A10(19) RA21(36)
A11(20) RA22(37)
A12(21) RA23(38)
A13(31) RMPX(20)
A14(32) /ROE(21)
NEO-E0 PROG slot #1 & #2
Y6(12) SDRA8(A49)
Y7(13) SDRA9(A50)
Y8(14) SDRA20(A51)
Y9(22) SDRA21(A52)
Y10(23) SDRA22(A53)
Y11(24) SDRA23(A54)
Y12(27) SDRMPX(A55)
Y13(28) SDROE(A56)

Direction control of NEO-G0 @ K9 is set to inverted /ROE from YM2610.

NEO-E0 74AS04
Y13(28) A5(11)
NEO-G0 74AS04
D0~D7 dir(40) Y5(10)


P ROM / 68k access

todo. some NEO-G0 for D0~D15? NEO-E0 for A1~A23?

M ROM / Z80 access

Z80 A0~A15 is buffered through NEO-E0 @ K10 to SDA0~SDA15 of both cart slots.

Z80 NEO-E0
A0(30) A1(64)
A1(31) A2(1)
A2(32) A3(2)
A3(33) A4(3)
A4(34) A5(4)
A5(35) A6(15)
A6(36) A7(16)
A7(37) A8(17)
A8(38) A9(18)
A9(39 A10(19)
A10(40) A11(20)
A11(1) A12(21)
A12(2) A13(31)
A13(3) A14(32)
A14(4) A15(33)
A15(5) A16(34)
NEO-E0 CHA slot #1 & #2
Y0(5) SDA0(A43)
Y1(6) SDA1(A44)
Y2(7) SDA2(A45)
Y3(8) SDA3(A46)
Y4(9) SDA4(A47)
Y5(11) SDA5(A48)
Y6(12) SDA6(A49)
Y7(13) SDA7(A50)
Y8(14) SDA8(A51)
Y9(22) SDA9(A52)
Y10(23) SDA10(A53)
Y11(24) SDA11(A54)
Y12(27) SDA12(A55)
Y13(28) SDA13(A56)
Y14(29) SDA14(A57)
Y15(30) SDA15(A58)

Z80 D0~D7 is multiplexed from each slot by NEO-257 @ J9. No need for bidirectional D0~D7 since only reads can be done from cart.

Z80 NEO-257
D0(14) Y8(40)
D1(15) Y9(41)
D2(12) Y10(43)
D3(8) Y11(44)
D4(7) Y12(55)
D5(9) Y13(56)
D6(10) Y14(59)
D7(13) Y15(60)
NEO-257 CHA slot #1
A8(36) CHA SDD0(B51)
A9(38) CHA SDD1(B52)
A10(45) CHA SDD2(B53)
A11(47) CHA SDD3(B54)
A12(51) CHA SDD4(B55)
A13(53) CHA SDD5(B56)
A14(62) CHA SDD6(B57)
A15(64) CHA SDD7(B58)
NEO-257 CHA slot #2
B8(37) CHA SDD0(B51)
B9(39) CHA SDD1(B52)
B10(46) CHA SDD2(B53)
B11(48) CHA SDD3(B54)
B12(52) CHA SDD4(B55)
B13(54) CHA SDD5(B56)
B14(63) CHA SDD6(B57)
B15(1) CHA SDD7(B58)

Multiplexer slot selection from NEO-F0, /OE from NEO-D0 and OE from 74HC259 to NEO-257. The 257 must only output to Z80 when it is trying to read ROM (NEO-D0) and the cart M1/S1 is selected (74HC259).

NEO-D0 NEO-257
SDROM(11) Y8~Y15 /OE(33)
NEO-F0 NEO-257
74HC259 NEO-257
Q5(10) Y8~Y15 OE(35)

NEO-D0 signals for Z80 reads are also buffered through NEO-E0 @ K10.

SDMRD(39) A17(36)
SDROM(11) A18(37)
SDRD0(45) A19(38)
SDRD1(46) A20(48)
NEO-E0 CHA slot #1 & #2
Y16(39) SDMRD(B50)
Y17(40) SDROM(B49)
Y18(41) SDRD0(B47)
Y19(43) SDRD1(B48)