Sachen SA8259A pinout

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Sachen SA8259A: 28-pin 0.6" DIP

Most of Sachen's mapper ICs have names that collide with other well-known ICs, presumably as an initial round of indirection to confuse would-be mass copiers. The 8259A is canonically the original IBM PC's Programmable Interrupt Controller.

              .---\/---.              
   PRG A15 <- | 01  28 | -- Vcc
 CIRAM A10 <- | 02  27 | -> r42
   PPU A11 -> | 03  26 | <- CPU A8 (+CE)
   PPU A13 -> | 04  25 | -> rX0
   PPU /RD -> | 05  24 | <- R/W
         ? ?? | 06  23 | <- M2
   PRG A16 <- | 07  22 | <- PPU A12
   CPU A14 -> | 08  21 | <- PPU A10
   CPU  A0 -> | 09  20 | <- /ROMSEL
       rX1 <- | 10  19 | -> r41
   CPU  D0 -> | 11  18 | <- CPU D2
   CPU  D1 -> | 12  17 | -> r60
   PRG A17 <- | 13  16 | -> rX2
       GND -- | 14  15 | -> r40
              '--------'

The exact connectivity of the pins labelled r?? depends on the corresponding mapper number or name allocated.

pin \ mapper 137 138 139 141
rX0 CHR A10 CHR A11 CHR A13 CHR A12
rX1 CHR A11 CHR A12 CHR A14 CHR A13
rX2 CHR A12 CHR A13 CHR A15 CHR A14
r40 CHR A14¹ CHR A14 CHR A16 CHR A15
r41 CHR A14¹ CHR A15 CHR A17 CHR A16
r42 CHR A14¹ CHR A16 CHR A18 CHR A17
r60 CHR A13¹ n/c n/c n/c

¹: r40, r41, r42, and r60 go through a 74LS253 dual 4 to 1 multiplexer and a 74LS257 quad 2 to 1 multiplexer to produce 4x1+4F CHR banking

Reference: Cah4e3 ( http://cah4e3.shedevr.org.ru/%5Blst%5D-sachen-mappers.txt )