Talk:Sachen 8259

Pins

Whatever this IC looked like, if it was ever not just an epoxy blob, it probably existed in a 24-pin package.

For the behavior described here, the following 22 signals must be attached to it: Vcc Gnd /ROMSEL CPU_A14 CPU_A8 CPU_A0 CPU_M2 CPU_D0 CPU_D1 CPU_D2 PRG_A15 PRG_A16 PRG_A17 PPU_A10 PPU_A11 PPU_A12 CHR_A11 CHR_A12 CHR_A13 CHR_A14 CHR_A15 CHR_A16

Plus at least one of the following two: CIRAM_A10 or PPU_A13

The behavior described on iNES Mapper 137 is satisfied by the addition of one 74'153 as well as specifying one extra digital output for the contents of register 6. —Lidnariq (talk) 13:33, 31 January 2014 (MST)

Unfortunately, I don't know much about the chip(s); just what I've seen other emulators implement. But what you say does make sense. Natt (talk) 13:39, 31 January 2014 (MST)

Evidently I'm wrong! The Pirated (Pirates') Games Forum had a thread ( s4.zetaboards.com/PGC_Forums/topic/9974526/1/ ) with a picture of Rockball's PCB. It was on the PCB TC-A003-72P and had two mask ROMs, a place for PRGRAM, a CIC stunner, and a 28-pin 0.6" DIP labelled SA8259A. ( img31.imageshack.us/img31/8521/r93f.jpg ). Cah4e3 has a writeup, including a pinout, which I'll incorporate into the wiki here shortly. —Lidnariq (talk) 16:00, 31 January 2014 (MST)

Indirect addressing

It'd be nice to be consistent across the wiki about how we refer to indirectly addressed mapper registers:

• Yamaha synthesizer IC datasheets call it address/data
• The AY-3-8910 datasheet calls it 'latch address'/'write to psg'
• The TI SN7649x datasheet calls it register address/data
• MMC3 calls it bank/bank data
• Sachen 8259 calls it select/(data/internal)
• FME-7 calls it command/parameter
• Sunsoft 5B audio calls it audio register select/write
• VRC7 audio calls it register select/write

—Lidnariq (talk) 13:33, 31 January 2014 (MST)