New csa2 FAQs: F002FDISK (Part 2 of 2)

[Rubywand <rubywand@swbell.net>]

From: Stephen Buggie

015- Can I replace a bombed Apple II 3.5" drive mechanism with
     one from a Mac?

     Yes. 3.5" drive mechanisms are cheaply and abundantly available
from the Macintosh world. Although Apple II users have increased their
interest in 3.5" drives, these drives have declined in their utility for
Mac users who have shifted to hard drives, CD-ROM, and flopticals.  Few
Mac owners have use for the external 3.5" drive any more; if they have
not yet discarded their external 3.5" drive, it is now in storage.


     MAC AND APPLE II 3.5" DRIVES: SIMILARITIES/DIFFERENCES

     The basic Sony 3.5" mechanism is shared by Mac and Apple II.  It
stores 800K of data on a two-sided disk.  Unlike the IBM version with
its constant rotational speed, Mac/Apple II drives maintain constant
head velocity by varying the rotational speed as the head assembly
approaches towards or moves away from the disk hub.  Mac and Apple II
drives differ in their track sectoring arrangements, so disks cannot be
read directly without special translational software.  The opportunity
for compatible disk sharing was lost during development, because rival
teams working on Mac/Apple II drives went their separate ways (Steve
Weyhrich, APPLE II HISTORY, Pt. 9, 1992).

     The platinum 3.5" drive supplied with the IIgs is directly
compatible with the Mac, although the Mac ignores its front panel manual
eject button; Mac disk ejection is handled strictly by the desktop trash
icon command.  An older version of the external Mac 3.5" drive lacks the
manual eject button and, in its casing, is plug-incompatible with Apple
II.  Thanks to advice provided by Ken Watanabe, I learned that the inner
mechanism is identical  among all versions of 800K Mac and Apple II
drives, including the internal drive mechanism in the Mac CPU.  This is
good news for Apple II users who wish to transplant the abundantly
available Mac mechanism into their platinum 3.5" drive casing.


            WHAT ABOUT THE APPLE UNIDISK 3.5" DRIVE?

     The classic white Unidisk drive was released in 1985 as a 3.5"
platform for the IIe and IIc.  This release date was 18 months prior to
the introduction of the IIgs.  Disks written by the Unidisk 3.5 and
Platinum 3.5 drives are fully interchangeable; the two models differed
because the earlier Unidisk 3.5 used an intelligent
microprocessor-controlled analog board to slow the data transfer rate to
match the IIe/IIc parameters.  This slowdown was not needed for the
popular platinum  3.5 drive used by the IIgs.

     Can the Mac mechanism be transplanted to the Unidisk 3.5 casing?
Probably yes, but this has not yet been verified.  I am reluctant tohack
with the working Unidisk 3.5's attached to my IIC's.  I now seek a
mechanically jammed Unidisk 3.5 drive to verify whether its life can be
resurrected with a Mac transplant.


            FINDING A USED MAC 3.5" DRIVE MECHANISM

     The internall DSDD 800k drive mechanism can be salvaged from any
mid-vintage Mac except for early models (Mac 128, Fat Mac 512) ----
those two models used a quaint single-sided 400k drive.  Suitable models
include the Mac Plus, Mac SE, Mac II, or other Macs that have the
standard DSDD 800K mechanism --- newer Macs have incompatible high
density drives.  Get a genuine Mac Sony drive mechanism, not a clone;
the suitability of non-Sony clones is uncertain.

     Salvaged internal drives must be removed from the Mac internal
mounting bracket --- take out the four side-mounted bolts, and slide the
mechanism forward.  The early version of the external Mac mechanism is
mounted in a plastic casing that resembles the Apple II platinum drive
except that the manual eject button is absent.

     Remove the mechanism from the casing, but save its round external
cable and db-19 plug --- that cable/plug can be used later to adapt
flat-ribbon Apple II drives for use with the IIgs or IIIc!  The Mac
externaldrive's plastic casing can be saved for use as a coin bank, or
discarded.

     You should anticipate  that the older Mac drive has had plenty of
use; most Mac users have fewer drives attached to their computer than is
common for the Apple II.

     The 3.5" drives are sturdier than hard drives, but to protect the
drive's head assembly from damage during rough shipment, the seller
should be asked to ship the unit with a disk inserted.


     DISASSEMBLY OF THE APPLE 3.5" PLATINUM DRIVE

     Use a well-light work area that gives you plenty of elbow room,
with containers to hold bolts and other small parts  All dimensions
(left/right/top/bottom/front/rear) refer to the unit's own dimensions,
NOT to your own egocentric viewpoint as the observer.  Standard
precautions against static or other electrical damage must be followed:
Discharge static frequently by touching grounded metal, wear a grounded
wrist strap, hand all power  OFF when attaching/removing drives, put
insulating tape over the db-19 drive plug when not in use.

     Move slowly and patiently when removing or inserting the mechanism
from its housing ---- metal parts must not be forced or bent.  These
tools areneeded: (a) medium and small Phillips-head screwdrivers, (b) a
small pliers, and (c) a fine-tipped felt marker.  This procedure was
outlined in an essay by Lorne Walton (Apples BC, 1992), but many further
details have been added here to facilitate disassembly and drive
replacement.


     The first step is to remove the worn/defective mechanism from its
Apple II platinum casing.  Flip the casing on its back and rest it on
soft cloth.  Re,ove the four shiny bolts from the bottom of the casing.
With the unit inverted, slowly lift the bottom half-shell of the plastic
casing upward and push the external cable's attached grommet towards the
upper casing.  The unit's bottom casing should come off cleany.

     Use the felt marker to label the unit's own main dimensions,
writing on the metal internal shroud: front-bottom, rear-bottom, left
side, right side. Examine the metal innards as they lie upside down in
the upper casing. Note that a red and black wire pair are tucked on the
inner edge of each side --- These two wires go to the eject switch
(right front) and to the red in-use LED lamp (left front).

     At the unit's rear, observe that the wire pairs terminate in RED
and BLACK plugs.  Use the felt-tipped marker to write "R" and "B" on
nearby metal surfaces to identifythe positions of these two plugs. These
letters will help during reassembly when reinsterting the two plugs onto
their proper pins.  Next, use the small pliers to grasp each plug,
slowly and carefully pulling it backwards to remove it from its mounting
pins.


     With the black and red plugs each removed, slide the top plastic
cover in a rear-to-front direction, past the metal-enshrouded mechanism.
The wire-pairs from the eject-button and also from the in-use LED lamp
should remain tucked into their plastic side-braces.

     You now hold the mechanism, enshrouded in its grey metal shielding,
with the external db-19 cable protruding from the rear. Remove the two
medium Phillips mounting bolts (with flat washers) from each side. 
Remove the single medium Phillips bolt/washer that is centered on the
upper-rear metal shroud. Then lift off the upper-rear should and look
inside.

     Note that the round external cable terminates in a familiar IDE-20
flat-ribbon connector that plugs into the inner mechanism.  Unplug that
inner connector --- the small pliers can be used to rock and pull the
connector towards the rear.  With the IDE-20ribbon connector unplugged,
the inner mechanism can be slid forward and out.

     As you hold the inner mechanism in your hand, observe that a shiny
thin metal shroud covers its to and sides.  Use the felt-tipped pen to
label this shrou's dimension: TOP-FRONT and TOP-REAR.  This thin shroud
should be removed by rocking it and spreading its thin side-tabs.  At
this point, you have the bare mechanism in your hand, with heads visible
from its top perspective, and with pancake motor visible underneath.

     You are now ready to begin reassembly, but pause to appreciate what
is before you.  Hold the old mechanism and its Mac replacement
side-by-side --- they should appear identical.  The date of manufacture
is coded on a sticker on the pancake motor (e.g., 8809 = September
1989).  Apply rubbing alcohol with a cotton swab to clean the surfaces
of both read/write heads.


                                REASSEMBLY

     Remount the innermost top-and-sides metal shroud, taking care that
its "fingers" have clicked into place on the mechanism's sides. When
properly fited, both bolt-holes on each side will be visible through the
shroud's thin metal. If the shroud does not fit, or if the bolt-holes
are not seen, check with your dimensional labels to verify that the
front and rear have not been reversed.

     With the top/side inner shroud correctly in place, then reverse the
disassembly steps: Slide the mechanism through the front of the metal
shroud. Reattach the IDE-20 internal ribbon connector, align the two
bolt holes on each side of the outer shroud with the mechanism and
reinstall the four medium Phillips bolts and their washers.  Then
reattach the rear-upper shroud with its centered bolt and washer.
Reassembly of the outer metal shroud is now finished!


     The final reassembly task is to refit the enshrouded mechanism into
the plastic outer casing.  Lay the inverted UPPER plastic half-shell on
the bench,with its front facing away from you.

     Observe the small red or black wires tucked along the sides of the
upper plastic half-shell. With the metal enshrouded drive mechanism
upside down, it should be slid into the plastic top-shell, from  its
rear to its front.  Check that the red-black wires remain tucked along
the inner edge between the plastic casing and the metal shroud.  Insert
the black and red plugs into their respective connectors.  Note the "R"
and "B" markings you wrote on the metal shroud; those markings will
guide the plugs' insertion into their proper connectors.

     The oblong-shaped grommet attached to the round external cable
should be fitted first to the bottom plastic half-shell casing, which is
then mated to the top casing.  Reattach the four small shiny Phillips
bolts through the bottom plastic half-shell, and you're done!

____________________________



From: David Empson

016- I have one 5.25" drive connected to my GS, but the System 6.0.1
     Finder display shows two 5.25" icons!? How can I fix this?

     You need to change the AppleDisk5.25 driver file's auxilary
filetype from $010E to $0101. You can use File Manager (an NDA utility)
to make the change.

     For a standard GS/OS device driver, the lower six bits specify the
number of devices supported by the driver (see the file type note on
GS/OS drivers: FTN.BB.XXXX), so the maximum number of devices that can
be supported by a single driver is 63.  You should NEVER increase this
higher than the original value, because the driver probably doesn't have
space in its device tables to support more drivers than it originally
claimed to.

     The AppleDisk5.25 driver supports a maximum of 14 devices - two
5.25" drives for each available slot.  (In theory, it should be able to
support 16: all seven real slots, plus the built-in disk port, but Apple
never completed the implementation of dynamic slot switching for
drivers, probably for compatibility reasons.)

     Don't change any of the higher order bits.  The high order byte
specifies the type of driver ($01 = GS/OS device driver), and the top
two bits of the low order byte specify the type of GS/OS driver (00 =
standard).

NOTE: All of the above applies ONLY to GS/OS standard device drivers,
not to GS/OS supervisory drivers, printer drivers, or anything else. See
the filetype note for further information.

     There is one bit in the auxiliary type which is the same for all
types of drivers: bit 15 set ($8000) indicates the driver is inactive
(this is what Finder toggles when you click on the "Inactive" check
box).

____________________________



From: Neil Parker

017- How does one distinguish between a 13 and 16-sector Disk ][
     interface card?

     For a while at least, new 16-sector Disk II cards shipped with a
little white circular sticker depicting a red Apple with the number "16"
in the middle.

     But the sticker is hardly a reliable test.  A better test is to
look look at the part numbers of the P5 PROM (the lower left chip on the
card) and the P6 PROM (left column, second from the top).

          13-sector    16-sector
          ---------    ---------
     P5   341-0009-xx  341-0027-xx
     P6   341-0010-xx  341-0028-xx

The 16-sector PROMs may also be labelled "P5A" and "P6A".


A program can test the card type by looking at its slot ROM space.  The
signature bytes are as follows:

     $Cn01: 20
     $Cn03: 00
     $Cn05: 03
     $Cn07: 3C
     $CnFF: 00 if 16-sector, FF if 13-sector

For example,

     1  REM Scan the slots for Disk II interfaces
     2  REM By Neil Parker
     10  FOR S = 1 TO 7
     20 A = 49152 + 256 * S
     30  IF  PEEK (A + 1) <  > 32 OR  PEEK (A + 3) <  > 0 OR
        PEEK (A + 5) <  > 3 OR  PEEK (A + 7) <  > 60 THEN 100
     40  PRINT "Disk II (";
     50 T =  PEEK (A + 255)
     60  IF T = 0 THEN  PRINT "16-sector";: GOTO 90
     70  IF T = 255 THEN  PRINT "13-sector";: GOTO 90
     80  PRINT "other";
     90  PRINT ") in slot "S
     100  NEXT

____________________________



From: Dan DeMaggio

018- Can a Disk ][ Drive be used on a IIc or GS smartport?

     Yes. Call Jameco Electronics. Get the S20-pin header- to -DB19-pin
connector module. It is intended for adapting II/II+ drives for IIc.
(Part# 10022; Product name: AAM APPLE IIC ADAPTER; price: $3.95)

---------------------------


019- What's the scoop on the 3.5" High Density drive?

     In order to do High Density on the Apple II, you will need both the
High Density 3.5" drive and the Apple 3.5" HD controller. If you don't
have both, you will only be able to do regular density. Of course, you
will also need High Density diskettes.

     Once you have collected the above items, you are in for a pleasant
surprise. ProDos 8 programs not only recognize it, but most programs
format and recognize HD disks just fine. You can even boot off of a HD
disk, allowing plenty of room for GS/OS Desk Accessories and such.

     There are a few drawbacks: You cannot boot copy-protected software
or some FTA demos. You can't daisy-chain a 5.25" on an HD card. Also, it
takes up a slot, even on the GS.

______________________________



From: Dave Althoff

020- What DuoDisk mods are necessary?

There are two capacitors which must be clipped from the board on the
DuoDisk regardless of what machine you intend to use them on.  Failure
to do this can cause very nasty failures...for instance, the
copy-protection scheme used on Pascal format applications, and possibly
others (when I watched it happen, it was with PFS:File) can, under
certain circumstances, cause the drive to start writing
unexpectedly...say, during a re-boot...thus trashing the disk without
regard to the write-protect switch.

If you plan to use the DuoDisk on a ROM-01 IIgs, there is/are one or two
resistors which must be clipped from the board.  This reduces the
drive's power consumption, and makes it compatible with the IIgs without
affecting its compatability with other machines.

Both of these are described in a technote or two, but I don't recall
exactly which one...

----------------------------


From: Chet Gerhardt

Regarding : "Data on Disk is damaged when using "Open-Apple-CTL-Reset"
for rebooting, or when using software with certain copyright protection
schemes. Analog board PN is 676-[]101 or 676-[]102."

The Modification From My technical Notes, It is easy to do:

The analog board is the one inside Drive 1 in the Duodisk.  You may have
to unplug the cable near the back right of the board to see the board's
model number.  Anyway, if you have the -101 or -102 board, just cut off
capacitors C29 and C30 (at board locations A1 and B1, respectively).

I have done this with all DuoDisks I have sold and my own DuoDisks.  It
is amazing that after all of this time most still have not had the mod
done...

Sorry,  I can't find my notes on the IIgs modification.

____________________________



From: John L. Graham

021- How do I fix a false Write Protect on duo disk?

     I recently ran into this problem with a Disk II. It insisted the
disk was write protected. I checked the write protect switch, but it was
okay. I pulled all the chips out of the analog board inside the drive,
cleaned the contacts with a clean pencil eraser (one was _really_ dirty,
almost looked burnt) and re-installed them. Voila! The problem went
away.


____________________________



From: Rubywand

022- Both of my Disk ]['s come on when booting! How can I
     fix this?

     Basically, it sounds like Drive 2 does not know when to stay OFF.
There are three fairly high-probability places where a glitch may cause
this to happen:

 1. The 74LS132 on the Disk ][ Controller card may have a blown gate or
some pins may be making poor or no contact. Try unplugging and
re-socketing the IC. This usually takes care of bad contact problems.
(Or, you can replace the 74LS132 IC with another 74LS132 or 74132. A
74LS00 or 7400 may work, too.) Also unplug and re-socket the 9334 and
556.

 2. The ULN2003 IC on the Drive 2 main circuit board may have a bad gate
or may have developed some poor pin-to-socket contacts. Remove the drive
cover. Unplug and re-socket the ULN2003 IC. (Directly replacing a blown
ULN2003 could be difficult. If you do not mind doing some rewiring, a
couple 7404's should get the job done.)

 3. Drive 2's cable may have developed a short between pins 14 and 16.
Mark the position of the cable at the Controller card and at the Drive 2
circuit board and unplug the cable at each end. Use an Ohm meter to
check for shorts between adjacent pins. If you find a short between 14
and any other pin you can try repairing the cable or cutting out line 14
and running a new lead; or you can get a replacement cable.