Radio Shack TRS-80 Service Manual page 105

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WRITE
WRITE/ERASE
DATA
CURRE"'T SOURCE
AI'<O WAVEFORM
GENERATOR
..... RITE ENA8LE
READ DATA READ AMl'llFIER
A"'O DIGITIZER
FIGURE 4_ FUNCTIONAL BLOCK DIAGRAM
DATA ELECTRONICS
Information can be recorded on the diskette using a double-
frequency code. Figure 5 illustrates the magnetization pro-
files in each bit cell for the number sequence shown.
All signals required to control the data electronics are pro-
vided by the user system and are shown in the Block Dia-
gram (Figure 4). These control signals are:
*
SELECT
The erase gaps provide an erased guard band on either side
of the recorded track. This accommodates the tolerances
in track positioning.
*
WRITE ENABLE
*
WRITE DATA
The READ DATA composite signal is sent to the user
system via the interface.
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FIGURE 5. FM RECORDING
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