Data Interface; Mfm Write Data Timing; Mfm Read Data Timing - Quantum Q2080 Product Description

1.3.9 DATA INTERFACE
The function of each of the five (5) data signals is described below:
• MFM WRITE DATA - Provided there is a LO level on the WRITE GATE control line the transi-
tion of the
+
MFM WRITE DATA line more positive than the -MFM WRITE DATA line will cause
a flux reversal to be written on the disk. During read operations the
+
MFM WRITE DATA line
must be held more negative than the -MFM WRITE DATA line. Figure 1-24 shows the write data
timing.
-
DRIVESELECT~~~~~~~~~~~~~~~~~~~~~~~
-HEADSELECT--,~~~~~
__
~
____
~
______
~
____
~~
__
~
___
- WR ITE GATE __
I..- _____
2_0_Il_S_M_A_X ___
---+- __ ...
1
I
1 ---'1 1"-
50 7l S TO 150 7l S
+ MFM WRITE DATA ____________________
r--LrLrl _________ _
460 7lS MAX
---.-11..- -'1 I-
BIT CELL
=
230 7lS TYP
FIGURE 1-24
MFM WRITE DATA TIMING
• MFM READ DATA - Provided there is a HI level on the WRITE GATE control line, the transi-
tion of the
+
MFM READ DATA line more positive than the -MFM READ DATA line indicates a
flux reversal was detected on the track. Figure 1-25 shows the read data timing.
- DRIVE SELECT--,
-HEADSELECT-,~~--~~~~----~-~~~~~----~-
20 p.s MAX
_I I .....
-'1 1.-
50 1lS TYP
+
MFM VALID READ DATA_--,
-WRITE GATE
~
BIT CELL
=
230 TlS TYP
--..J
~ 20
p.s MAX
I I
WRITE (REFERENCE)
FIGURE 1-25
MFM READ DATA TIMING
• DRIVE SELECTED - This open collector line will go to a LO level when this drive is selected by
the appropriate drive select line.
• RADIAL SEEK COMPLETE - Select this output by installing Jumper D at PCB location 11.
When selected, a LO level on this line indicates the R/W heads have settled at a cylinder and a read,
write or another seek may take place. This signal is not gated with drive select.
• RADIAL INDEX - Select this output by installing Jumper H at PCB location 11. When selected,
a LO pulse of 10 1'-sec duration on this line indicates the beginning of a track. This signal is not
gated with drive select.
1-23 REV A (01184)