Sachen SA8259A pinout

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 )