Commodore Amiga A1000, Hardware Reference Manual

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DSKBYTR - DISK DATA BYTE AND STATUS READ (READ-ONLY)
This register is the disk-microprocessor data buffer. In read mode, data from the disk is
placed into this register one byte at a time. As each byte is received into the register, the
DSKBYT bit is set true. DSKBYT is cleared when the DSKBYTR register is read.
DSKBYTR may be used to synchronize the processor to the disk rotation before issuing a
read or write under DMA control.
Table 8-7: DSKBYTR Register
Bit
Number Name Function
15 DSKBYT When set, indicates that this register contains
a valid byte of data (reset by reading this
register).
14 DMAON Indicates when DMA is actually enabled. All the
various DMA bits must be true. This means the
DMAEN bit in DKSLEN, and the DSKEN & DMAEN bits in
DMACON.
13 DISKWRITE The disk write bit (in DSKLEN) is enabled.
12 WORDEQUAL Indicates the DISKSYNC register equals the disk
input stream. This bit is true only while the
input stream matches the sync register (as little
as two microseconds).
11-8 Currently unused; don't depend on read value.
7-0 DATA Disk byte data.
ADKCON AND ADKCONR - AUDIO AND DISK CONTROL REGISTER
ADKCON is the write-only address and ADKCONR is the read-only address for this register.
Not all of the bits are dedicated to the disk. Bit 15 of this register allows independent
setting or clearing of any bit or bits. If bit 15 is a one on a write, any ones in positions 0-
14 will set the corresponding bit. If bit 15 is a zero, any ones will clear the corresponding
bit.
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