Subject: SMD disk interface pinout/specs

From: "Jim Donaghue" <[email-masked]>
Date: Mon Mar 3 19:53:08 2003

Does anyone have the specs/pinout for the 60-pin and 26-pin SMD disk drive interface?

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From: Tom Uban <[email-masked]>
Date: Mon Mar 3 22:38:36 2003

According to my Emulex SC31 manual:

Pins    Lo/Hi   Signal                          (Tag 3 
Function)                From/To
-----------------------------------------------------------------------------------------------------------------------
A Cable:
         22,52   Unit Select Tag                                         To
         23,53   Unit Select Bit 0                                       To
         24,54   Unit Select Bit 1                                       To
         26,56   Unit Select Bit 2                                       To
         27,57   Unit Select Bit 3                                       To
         1,31    Tag 1                                                   To
         2,32    Tag 2                                                   To
         3,33    Tag 3                                                   To
         4,34    Bit 0                           (Write Gate)            To
         5,35    Bit 1                           (Read Gate)             To
         6,36    Bit 2                           (Servo Offset Plus)     To
         7,37    Bit 3                           (Servo Offset Minus)    To
         8,38    Bit 4                           (Fault Clear)           To
         9,39    Bit 5                           (AM Enable)             To
         10,40   Bit 6                           (Return To 
Zero)                To
         11,41   Bit 7                           (Data Strobe Early)     To
         12,42   Bit 8                           (Data Strobe Late)      To
         13,43   Bit 9                           (Release)               To
         30,60   Bit 10                                                  To
         14,44   Open Cable Detect                                       To
         15,45   Fault                                                   From
         16,46   Seek Error                                              From
         17,47   On Cylinder                                             From
         18,48   Index                                                   From
         19,49   Unit Ready                                              From
         20,50   Address Mark Found                                      From
         21,51   Busy (dual port only)                                   From
         25,55   Sector                                                  From
         28,58   Write Protected                                         From
            29   Power Sequence Hold                                     To
            59   Power Sequence Pick                                     To

B Cable:
         8,20    Write Data                                              To
         6,19    Write Clock                                             To
         2,14    Servo Clock                                             From
         3,16    Read Data                                               From
         5,17    Read Clock                                              From
         10,23   Seek End                                                From
         22,9    Unit Selected                                           From
         12,24   Index                                                   From
         13,26   Sector                                                  From

Please excuse any typos...

--tom

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From: Jeffrey Sharp <[email-masked]>
Date: Tue Mar 4 12:42:33 2003

What are the differences between SMD-E and SMD-O? Are there other types of
SMD? Where can I find more information on SMD?

-- 
Jeffrey Sharp

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From: jim <[email-masked]>
Date: Tue Mar 4 12:43:01 2003

> SMD? Where can I find more information on SMD?

i think you may be referring to the normal density and high density versions.

If I recall original SMD had about 26K / track.  EMD drives from CDC had twice

that. density.

The main thing that was a problem was that there was originally a chip that
would
do CRC generation in the original 7400 series IC line.  This chip in the same
circuitry
could not keep up with the higher speed SMD and demanded a newer chip.

I recall that most designers went with ECC chips in newer designs, rather than
the
original CRC, as a result of newer logic on the market then.

Our original design at a company I worked for was out in around 1981 or 1982.

If I recall the newer SMD designs were out around 1984 or so.  We did not
support them due to having a very small market to support, and low demand for
further updates.

Jim