No to jednak nie rozumiem :), jeżeli RDY pauzuje procka, pozwalając na kontynuację opercji na pamięci i I/O, choć może znalazłem odpowiedź, a nie umiem jej zinterpretować:
On the Atari, there are two microprocessors, ANTIC and the 6502. To allow
them to coexist, ANTIC must shut off the 6502, a process called DMA. The
6502B supports DMA, but in Atari's implementation, it required 4 chips. The
6502C has an extra line called HALT. It is controlled by ANTIC which uses it
whenever it needs the data/address bus.
ANTIC ("Alpha-Numeric Television Interface Circuit") is a microprocessor
dedicated to the television display. It is a true microprocessor; it has an
instruction set, a program (called the display list), and data. The display
list and the display data are written into RAM by the 6502. ANTIC retrieves
this information from RAM using direct memory access (DMA). It processes the
higher level instructions in the display list and translates these
instructions into a real-time stream of simple instructions to GTIA.
i conieco o Freddie'm (co się dzieje, jak go nie ma ?):
The XEGS has a FREDDIE but it doesn't have the extended RAM.
Even if it did, you would still need the chip that does the REAL bank
switching. It is a small 16-pin chip (Atari/Best Electronics catalog number
CO25953: rev9/page 42). It gets RAS from FREDDIE, the bank select bits from
PIA, A14, A15 and the 6502 halt signal to control which bank of 8 chips RAS
goes to. A14 and A15 then go to FREDDIE for the address range of the extra
memory bank (or normal address range with no bank switching). The ANTIC/6502
select bits in combination with the 6502 halt line, control the switching of
the PIA bank number bits to A14/A15 and which bank of memory RAS goes to.
podkreślenie moje.
//EDIT: stąd: http://www.faqs.org/faqs/atari-8-bit/fa … on-12.html
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