Commodore 1570 - Page 97

CONTROLLER STATUS (MFM)
OOOX ..... OK
0010
...... SECTOR NOT FOUND
0011
...... NO ADDRESS MARK
01 00 ...... RESERVED
0101
...... DATA CRC ERROR
0110
...... FORMAT ERROR
0111
...... VERIFY ERROR
1000
...... WRITE PROTECT ERROR
1001 ...... HEADER BLOCK CHECKSUM ERROR
1010
...... RESERVED
1011 ...... DISK CHANGE
1100
...... RESERVED
1101 ...... RESERVED
1110
...... SYNTAX ERROR
1111
...... NO DRIVE PRESENT
BURST TRANSFER PROTOCOL
Before using the following burst transfer routines, you must determine whether or not the
peripheral
is a fast device. The Fast Serial (byte mode) protocol makes that determination
internally when you include a query routine (send-cmd-string;). This routine addresses the
peripheral
as a listener and thereby determines its speed.
BURST READ
send-cmd-string;
if device-fast then
serial-in;
repeat
read-error;
toggle clock;
repeat
wait-byte;
if status = ok then
toggle-clock;
repeat
wait-byte;
toggle-clock;
store-byte;
until end-of-sector;
until no-more-sectors;
set-clock-high;
else
read-1541;
89
(*determine speed*)
(*turn 6526 to input*)
(*repeat for all sectors*)
(*retrieve error byte*)
(*wait for status*)
(*wait for byte*)
(*start double buffer*)
(*get data*)
(* start next*)
(*save data*)
(*release clock line*)
(*send unit read*)
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