RANA Systems Elite Controller, Руководство пользователя, Страница: 172 / 328

ELITE SERIES USER MANUAL THEORY OF OPERATION
DOS 3.3 re-enters at $Cn5C using a 6502 JMP.
When the PROM is finished, the second stage
expects it to transfer control back, via a JMP,
to $801.
DOS 3.2.1 does not expect the boot PROM to try
to decode the data read on the later calls (the
boot sector is a special encoding scheme which
differs from the rest of a 13 sector disk).
However, DOS 3.3 does require the boot PROM to
decode on these later sectors.
NOTE: The Rana boot code adheres to all the
above standard Apple DOS booting protocols, and
to several extensions to this protocol in order
to support existing software packages.
7 . 2 . 3 . H a r d w a r e
The Elite Controller Card has full data buffer-
ing, using a bi-directional bus driver, which
pro vides more drive than other controllers yet
requires very little drive from the bus. Exten-
sive power switching reduces the power consump-
tion of the data buffer and other circuits.
7 . 2 . 4 . E P R O M L o g i c
The EPROM is split into two sections ($000—$6FF
and $ 700-$7FF). Both sections are mapped into
$C800-$CFFF; however only the $000-$6FF section,
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