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 |
| PPU A10 | PPU A11 | PPU A10 | ||
| PPU A11 | PPU A10 | PPU A11 | ||
| PPU A12 | PPU A11 | PPU A12 | ||
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 )