MMU

Description

Selects cartridge banks, hw chips, osrom, BASIC rom. In older machines had no Atari number, was PAL16L8.

Catalogue numbers

CO60609 (1200/1400)
CO61618 (XL/XE)
C101686 (XEGS) = 16L8

Pinout (CO61618)

/MAP	IN from PB7 - low selftest on, hi selftest off
RD4	IN from cartridge port
RD5	IN from cartridge port
REN	IN from PB0 - low OS off, hi OS on
/REF	IN refresh
/S5	OUT cart bank select
/BASIC	OUT basic rom chip select
/MPD	IN MPD PBI
/OS	OUT OS rom chip select
/CI	OUT CAS inhibit
/IO	OUT goes to 74LS138, selects hw chips (Y0 - GTIA, Y2 - POKEY, Y3 - PIA, Y5 - CCTL)
/BE	IN from PB1 - low BASIC in, hi BASIC out
/S4	OUT cart bank select

Here is PAL (2 KB SRC) source by Bob Woolley and GAL (0 KB SRC) source from Erhard Puetz. I didn't check them for correctness (which means nothing... :)