Archive-name: apple2/faq/part9
Posting-Frequency: monthly
Last-modified: 2008/10/01
URL: http://home.swbell.net/rubywand/A2FAQs1START.html


The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
the Ground Apple II archive, 1997-2008. Administrator: Steve Nelson

Csa2 FAQs-on-Ground ref: Csa2FDRIVE.txt  rev127 October 2008







Floppy Disk Drives


 001- How do I add a write-protect On-Off switch?
 002- How do I add external speed adjustment to my Disk ][ drive?
 003- How can I adjust my 5.25" drive for optimum performance?
 004- How do I clean my disk drive R/W head(s)?
 005- What is the pinout for a duodisk drive connecting cable?
 006- What DuoDisk mods are necessary?
 007- Will a Duodisk function correctly on my ROM 3 GS?
 008- How do I fix a false Write Protect?
 009- My 3.5 Disk Drives don't work! What should I try?
 010- I added SCSI; now, my 3.5" drives often fail to work. Why?
 011- Both of my Disk ]['s come on when booting! Is there a fix?
 012- In connecting a Disk II I misaligned the connectors. A fix?
 013- A sound like a shotgun going off came from my drive. A fix?
 014- Uni-disk and Laser drives: neither works with my IIc. Why?
 015- How do I replace a 3.5" drive mechanism with one from a Mac?
 016- I have one 5.25" drive. Sys6 shows two icons!? Is there a fix?
 017- How can I tell a 13 from a 16-sector Disk ][ controller card?
 018- Can a Disk ][ Drive be used on a IIc or GS smartport?
 019- How do I install a bi-color LED R/W indicator in my Disk ][?
 020- What's the scoop on the 3.5" High Density drive?
 021- What is a "UniDisk"?
 022- What is a "RAM disk"; and, how do I create one on my IIgs?
 023- Which 3.5" drive/interface combinations work on a IIe?
 024- How can I boot from my /RAM5 RAM disk?
 025- My 5.25" drive ruins every disk I insert. How can I fix it?
 026- Incorrect 'Disk Full' error on a 3.5" Unidisk drive. Why?






From: Stephen Buggie

001- How do I add a write-protect On-Off switch to my Disk ][ drive?


Adding an Auto/Manual Write-Protect (A/MWP) Switch

     Often, as when doing copying, it is useful to be able to guarantee
that a diskette is Write-Protected whether or not the side is notched.
Other times, it is convenient to defeat Write Protection-- for example,
when you wish to write to a diskette side which is not notched. And,
naturally, you also want a setting which permits Normal, notch-controlled,
Write-Protect.

     Based upon a circuit suggested by David Wilson (Australia), the A/MWP
enhancement offers full user control of Write Protect. The switch's three
positions are

Normal:      a diskette side must be notched to permit writing.
Protect ON:  Writing is prohibited regardless of notching.
Protect OFF: Writing is allowed regardless of notching.


A/MWP Step-by-Step

Unplug the drive from the disk controller and remove the case.

Drill a mounting hole. This can be at a convenient spot in the back or in
the plastic front panel. On the front, a good spot is at the lower left,
above and to the left of the "in use" LED. Another open spot is
at the upper right in the space just above the diskette slot; but, we're
saving this place for Part 2's enhancement. (You can't use the lower right,
of course, because this would mess up the "Apple" logo!)

Cut three wires (Brown, Black, and White) long enough to run from the
mounting point to the Large Connector plugged onto the back, middle of the
Disk ][ circuit board.

Solder the leads to a Single-Pole Triple-Throw mini toggle Switch:  Brown
to center, White to one end, Black to other end. Twist the leads or encase
them in tubing.

Mount the Switch. Normally, the Switch handle will point ...

o- in the Black lead direction for "Normal" (center and White connected)
o- at Center for "Protect ON" (no connection).
o- in the White lead direction for "Protect OFF" (center and
Black connected).


Mounting the switch with the Black lead on top is recommended because it is
easy to remember that Up = Normal. Route the leads to the area next to the
Large Connector. (Make sure no wires will get in the way of an inserted
diskette.)

Locate the Brown and Black leads coming from the Notch Detect micro-switch.
The leads are the Brown (bottom) and Black (top) pair near the right end of
the Large Connector (as viewed from the front of the drive).

Cut the Notch Detect micro-switch leads about 1" away from the Large Connector.

Connect the Black Notch Detect, Black Large Connector, and Black Switch
leads (i.e. strip ends, solder, and cover in heat-shrink tubing or tape).

Connect the Brown Notch Detect lead to the White Switch lead.

Connect the Brown Large Connector lead to the Brown Switch lead.


     Viola! Now you're ready to replace the cover, plug in the drive, and
try out your A/MWP enhanced Disk ][.

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


From: Ed Eastman

     Most of the time what you want to be able to do with a Write Protect
modification is turn On Write Enable when a disk is not notched. That is
what this mod for does. Details relate to the 5.25" Unidisk but the
method will also work with other Apple II 5.25" drives.

     The way the write protect sensor works on newer drives is that an LED
on one side shines on a phototransistor (the sensor) on the other side.
When there is a notch in the diskette you insert, light passes through the
gap and the sensor 'closes' to complete the Write Enable circuit. 

     What we will do is give the Write Enable circuit an alternate enable
option using an On/Off switch. A mini toggle switch is okay; but, I like to
use a small normally-open momentary contact pushbutton switch from Radio
Shack. It's compact, looks nice, and pressing the button for the few
seconds usually required for a file, etc. write is no problem.

     I normally mount the switch in the upper left part of the face plate,
opposite the light to balance the look. Drill a hole a little smaller than
required and use scissors or a larger drill to taper the hold to just where
you can screw in the switch. 

     Before soldering on leads and mounting the switch, decide where you
want to make the connections. You can locate the output leads from the
sensor and splice one switch lead to each; or, you can find the place on
the circuit board where the sensor leads go and connect there.

     On a Unidisk you will see a large connector labeled "CN1"
near the front. Pins 9 and 11 of CN1 are the write protect sensor
connections. More convenient connection points are the circuit board edge
side of R12 and the wire at J29.

     Solder on leads long enough to reach the connection points and screw
in the switch. On a Unidisk, connect one switch lead to the R12 point near
the edge and one to the wire at J29.

     Now when you need to override write protect on an unnotched disk, you
simply press the button while writing. Go ahead and plug in the drive and
give it a try.

____________________________



From: Stephen Buggie

002- How do I add an external speed adjustment to my Disk ][?

Reference: FAQs Resource file R006SPDKNOB.GIF


          Adding a Speed Control Knob to your Disk ][ Drive

     This article tells how to move speed adjustment from the Disk ]['s 
dark interior to a handy front-panel location and how to  "tune"
the drive for optimal performance.

     One drive-test software vendor states that Disk ][ is good for about
500 hours of normal use between speed adjustments-- not exactly a strong
argument for placing the control on the front panel! On the other hand many
of today's Disk ][ owners are interested in applications which go beyond
"normal use".

     Some utilities (e.g. DiversiCopy II) report rotational speed during
ongoing applications; so, relocating the speed adjuster to the front panel
is especially helpful. Similarly, users who want to back up their old,
copy-protected wares know that ready access to speed control is essential.

     Finally, there is no question that, whatever your applications,
periodic speed trimming will be required. When it is, you'll be very glad
_your_ Disk ][ has a front panel Speed Knob!



Adding Speed Knob

     To install Speed Knob you will need a good quality, linear taper 5k
Ohm potentiometer, some wires, and a knob with a pointer mark or some other
way to show position (e.g. a ring of numbers).  Most of the work, really,
consists of opening the drive and drilling a hole. There is no need to
disconnect the drive from the controller card.

1. Remove the 4 bottom bolts and slip off the case. Unscrew the 4 bottom
bolts holding the drive to the case bottom, and unplug the main ribbon
cable. The drive can now be moved to your work area.

2. Drill a hole properly sized and centered for mounting your 5k Ohm pot in
the upper right front panel.

3. Place the drive on its face and unscrew the 2 bolts which hold the small
daughter board to the drive. (Be ready to catch loose spacers, washers,
etc..)

4. Turn the small board over to the bottom side. Locate and cut the traces
going to the mini-pot speed adjuster as shown in pic R006SPDKNOB.GIF.

5. Cut three wires, White, Gray, Black, long enough to reach from the board
to the front panel. Connect these to your 5k Ohm pot and to the small
circuit board as shown in pic R006SPDKNOB.GIF. (In case you cannot view the
pic, what you're doing is substituting the new pot for the mini-pot. )

6. Re-mount the daughter board. Mount the 5k Ohm pot. Install knob.

7. Bring the drive back to the computer. Slide it onto the case bottom
plate, reconnect main ribbon cable, replace bottom bolts, slide on and
re-fasten case top.

     You can use Copy II Plus, XPS, APEX, or one of several other utilities
to set speed (see next question). A good starting adjustment will be near
the center of Speed Knob's range. Once speed is adjusted, you can loosen
and re-set the knob so that its position indicates a "correct"
speed setting.

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


003- How can I adjust my 5.25" drive for the best performance?

     The typical 5.25" drive will run for months with no need for
maintenance save an occassional dusting or session with a head-cleaner
disk. When adjustment is required, it will usually be to fine-tune Speed
or, less often, to set track centering.

     If a 5.25" drive has difficuly reading diskettes, including those
it created, and head-cleaning does not help, then, the odds are it's time
to adjust speed. If your drive is a Disk ][ and does not have the external
'Speed Knob' mod, look for a small hole on the lower right side near the
back-- some owners add this hole to allow easy access to the Speed
Adjustment mini-pot screw. If there is no hole, you will need to remove the
case. (Remove bolts on bottom and slide out the drive through the front.)

     On the 5.25" Apple 'Platinum Drive', the Speed Adjustment is
accessed through a small hole on the bottom of the drive near the front on
the right side. Non-Apple 5.25" drives may place the Speed Adjustment
almost anywhere. Look for a small hole through which you can see a screw
head. If you don't fine one, remove the case and look for a mini-pot
labeled "Speed" or something similar.

     The most popular speed adjustment software utility is, probably, dear
old Copy II Plus. From the menu, just select "Verify", then
"Drive Speed". Put a diskette into the drive you want to adjust
and, turning the Speed Knob (or min-pot shaft) use Copy II's numeric speed
display to zero-in on the 'magic' 200ms. number. (Standard Disk ][ rotation
speed is 300 rpm, which comes out to be 0.2 seconds per revolution.)

     Other speed adjustment utilities show an rpm number or a hires
pointer. Whatever, all speed check routines need to read AND write; so, you
will usually need a "scratch diskette" which you do not mind
having over-written.

     Track-center realignment is needed when a Disk ][ writes and reads its
own disks fine, but does not 'communicate' with many other Apple II
5.25" drives. It generates disk errors when reading disks written by
other drives and other drives have the same problem with its diskettes.

     CALL A.P.P.L.E's APTEST, now in the public domain, tests track-center
alignment. With  this software, the user checks the alignment of the drive
with disks regarded as well aligned --- such as Apple diskware supplied
with the computer or some unprotected, original, commercial software
diskette. (In a pinch, a diskette formatted by any drive that has no
problem reading most other diskettes should be okay.)

     Basically, a track-centering test tries to step your head between two
tracks of the 'standard' diskette and read the tracks on either side. If
the number of successful reads from each track is about equal, the head is
"centered" and your drive is well-aligned with the standard
diskette.

     The test may indicate serious misalignment. ("Aha! That explains
why my IIgs and II+ have problems reading each other's diskettes!") 
Centering adjustment is done by slightly repositioning the stepper motor
(mounted on the underside of the drive). This requires loosening the two
bolts holding the stepper-motor, rotating it clockwise or
counter-clockwise, and retightening.

     The adjustment/test process may require several repetitions. Each
time, the program will report "differential fractions". The
smaller these numbers, the closer you are to near perfect alignment with
tracks on the diskette.


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


From: Rubywand

     Suppose you have just one drive and it is so far out of adjustment
that it will not boot a speed adjustment utility diskette? In this case,
you can remove the drive cover, turn over the drive, and (probably) find
that the drive has a strobe pattern on the main pulley or flywheel.

     Set a fluorescent light near the drive (or do the adjustment in a room
with fluorescent lighting).  Get the drive spinning via power-on booting or
a PR#6 and adjust the speed for a stable pattern.

Note: If you live in a place which supplies 50Hz power and the drive is
intended for use in the U.S. or other country with 60Hz power, you may have
to experiment with + deviations in speed from a stable pattern.


____________________________



From: Rubywand

004- How do I clean my disk drive R/W head(s)?

     The easiest way to clean a drive's R/W head(s) is with a Cleaner
Diskette. This is a diskette with a paper disk such as the 5.25" and
3.5" Cleaner Diskettes available in Radio Shack's Disk Drive Head
Cleaner Kits. These kits usually include "Cleaning Fluid"
(isopropyl alcohol), too.

     The 5.25" Cleaner Diskette has panels you pop out to expose the
cleaning surface. Apple II 5.25" drives have a single head which
contacts the disk from the bottom and a pressure pad which presses against
the top side. So, pop out the panel on the bottom side of the Cleaner
Diskette and leave the top panel in place. When cleaning, insert the
diskette with the bottom side facing down. This lets the paper disk rub
against the head and avoids wear on the pressure pad.

     The 3.5" diskette has a small plastic panel you can snap out for
cleaning two-head drives. Since the standard 3.5" 800k Apple II drive
has two heads, snap out the panel so that both the top and bottom heads get
wiped.

     To clean your drive head(s), you sqirt a few drops of Cleaning Fluid
onto the Cleaner Diskette disk, insert it into the drive, and get the disk
spinning. Allow about 20 seconds for a 5.25" and a couple10-second
spins, with drops between spins, for a 3.5" drive. (Booting the
Cleaner Diskette is one way to get it spinning. If DOS or ProDOS is
installed, doing a CATALOG is another way. For example: CATALOG,S6,D2 would
get your 5.25" Drive 2 spinning. Doing a RESET will stop the
spinning.)

     If you think it has been several months since the drive was last
cleaned, repeat the procedure-- i.e remove the Cleaner Diskette, add more
fluid, etc.. As a rule, do not let the disk spin more than 15-20 seconds
for any cleaning cycle. This is especially a concern with 3.5" drives
where the heads are mounted on springs and much more subject to snagging
and being pulled out of alignment.

____________________________



From: Steve Jensen

005- I picked up an apple IIe and a duodisk drive at a thrift
     store. Could someone describe the connecting cable?

     I just checked the pinout on a Duodisk cable.  The numbers for the
pins are inside the plug by the pins, but I'll draw them for you.


DB 19 looking at the end of the cable:

    1   2   3   4   5   6   7   8   9  10
    o   o   o   o   o   o   o   o   o   o
      o   o   o   o   o   o   o   o   o
     11   12  13  14  15  16  17  18  19



DB 25 looking at the end of the cable:  (x = no pin)

     1   2   3   4   5   6   7   8   9   10  11  12  13
     x   o   o   o   o   o   o   o   o   o   o   o   x
       o   o   o   o   o   o   o   o   x   o   o   x
      14  15   16  17  18  19  20  21  22  23  24  25


Cable

DB 19   DB 25

1       2
2       4
3       9  & 21
4       10 & 14
5       23
6       7
7       19
8       20
9       8
10      12
11      15
12      16
13      17
14      18
15      5
16      24
17      11
18      3
19      6

____________________________



From: Steve Jensen and Jonathan Adams

006- What DuoDisk mods are necessary?

     The following is excerpted from an info file from my old bbs ...

     There are TWO modifications that should be made to Duodisk drives:

     The First one was recommended by Apple several ago to solve occasional
problems with trashing diskettes. The solution is to remove 2 capacitors.

     The Second modification is only required to solve a problem with
daisy-chaining on the GS Smartport, though the modified Duodisk will still
work fine on older Apple II's. It requires removing a resistor.



DUODISK MODIFICATION #1- REMOVAL OF TWO CAPACITORS

     This mod should be done on ALL Duodisks, no matter whether they're
used on //e's, IIGS's, etc.  The problem was that diskettes would sometimes
be damaged when doing an Open-Apple-CTL-Reset or when using disks with
certain kinds of copy protection.  The mod was in an Apple dealer service
bulletin several years ago for "analog board  PN 676-[]101 or
676-[]102."

     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
snip out Capacitors C29 and C30 at board locations A1 and B1, respectively.


DUODISK MODIFICATION #2- REMOVAL OF A RESISTOR

     This mod should be done for Duodisks used with a GS; otherwise, it is
optional. The problem is that the Duodisk draws just a little too much
current when connected to the GS Smartport. This can render other drives on
the chain inoperable. Problems are MOST likely to occur when the Duodisk is
daisy-chained from a Unidisk 3.5 Drive.

     Remove the top cover and turn the drive so that the identifying number
will be at the bottom left of the analog board. The number might read
676-[]101, 676-[]102 or 676-[]107. (ROM 3 GS users should check Q&A
007.) 

If the I.D.# for the analog board is 676-[]101 or 676-[]102, use a pair of
nippers and cut out resistor R8 (located at position A2).

If the I.D.# for the analog board is 676-[]107, use a pair of nippers and
cut out resistor R39 (located at position C3).

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


From: Dave Althoff

     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 lead to very nasty failures. For instance, some copy-protection
schemes can cause the drive to start writing unexpectedly-- say, during a
re-boot-- thus trashing the disk without regard to the write-protect
switch.

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


From: Chet Gerhardt

     I have done the capacitor removal mod 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.


____________________________



From: Steve Buggie

007- Will a Duodisk function correctly on my ROM 3 GS?

     I have three Duodisks.  The one connected to my flagship ROM 3 IIgs
has had the resistor and capacitors clipped out as recommended in a memo
from Mitch Spector. It works perfectly!

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

From: Rubywand 

     A Duodisk may not be entirely functional connected to the usual ROM 3
"Disk" connector (i.e. the SmartPort).  Users report that the
system may not start up unless a write-protected disk is inserted in the
Duodisk. Apple, in Tech Library notes #5010 and #5434, mentions these
reports and says that there is some code in the ROM 3 ROM that does not
handle the interface to a Duodisk properly. Apple's workaround is to
connect the Duodisk to a drive interface card instead of to the Smartport. 

____________________________



From: John L. Graham

008- How do I fix a false Write Protect?

     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

009- My 800K, 3.5 Disk Drive is no longer working on my IIGS.
     When a disk is inserted the drive tries to read it and then
     locks up the entire system forcing me to do a 3 finger reboot.
     Any suggestions on where to start troubleshooting?

     If you have a SCSI interface card plugged into your GS, you may have
run into a bug which seems to affect setting up of the diskette port. (See
the next question and answer.)

     Try cleaning the heads using a Head Cleaner Diskette, such as a paper
diskette + cleaning solution kit from Radio Shack. (See Q&A 004.)

     In a few rare cases, a drive may actually have globs of dust inside
which end up interferring with its operation. You can shine a flashlight
into the slot to check for a heavy dust buildup. The safest way to clean
out dust is to open the case and the drive and remove the dust. However,
you can try inserting a small cheap plastic artist's paintbrush (slightly
dampened) into the slot and, with a flashlight, _lightly_ sweeping around
to pick up dust. ("Lightly" means you do not push or snag on
anything, 

especially the R/W heads.) Blow into the slot and do another sweep with your brush.

     If cleaning does not seem to help, try wiggling the drive cable while
attempting to CAT a known-good, unprotected diskette in the drive. If
wiggling helps, you are likely to have a bad cable or a GS plug with a
loose connection to the motherboard.

     Try formatting a diskette. A drive which can format and R/W diskettes
it has recently formatted but cannot read most other diskettes probably has
heads which have become misaligned.

     Set your boot Slot to Slot 5 and try power-up booting a couple
bootable ProDOS diskettes known to be in good condition. If you can boot a
variety of disketts, including commercial game, etc. diskettes, the odds
are pretty good that your drive is okay.

     A 3.5" drive that, after cleaning, cannot boot known-good
diskettes is likely to have screwed-up heads. However, it's a good idea to
try unplugging and re-plugging the drive (with the computer OFF) and, then,
try another boot.

     If you have a 5.25" drive attached, boot ProDOS from the
5.25" drive and try some CAT's of non-protected known good 3.5"
diskettes in the 3.5" drive. As earlier, do the cable wiggling test
while attempting the CAT's.

     A very good test is to try out the drive on a friend's IIgs or IIc+.
If it continues to bomb, it is likely to have R/W heads which have become
badly misaligned, heads which are badly worn, or heads which have been
partially dislodged from the mountings. (The 3.5" drive's heads are
held in place by springy metal sheets. Unlike the mounting for the
5.25" Disk ][ head, these are fairly delicate. If anyone has tried
cleaning the heads by sticking in an alcohol swab and 'swishing around',
there is a good c

hance the head mountings are messed up.)

     Shops which replace heads are fairly rare. I had this done a few years
ago and the drive still works fine. However the charge is around $80. It is
cheaper and easier to get a good 2nd-hand drive at a swap-meet. You can,
also, look for a bargain Mac drive and do a "transplant" as
described by Steve Buggie in the Winter 1996 issue of II Alive.

     Steve Buggie is a good source of information on drive repairs. Check
out some of his recent posts to this newsgroup.

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


010- Sometimes the 3.5" drives on my GS do not function correctly.
     This started after adding a SCSI interface card.
     Is there a fix?

     This problem seems to crop up from time to time, especially when a
SCSI interface is present and when no device is connected and recognized on
the SCSI chain. (For example, you may have only a Zip Drive connected to
your SCSI interface; but, it is not powered ON or no Zip disk is inserted.)

     Evidently, something (e.g. a register or softswitch) involved in the
usual GS power-up routine relating to on-line devices gets messed up.
Arranging to have some active, on-line device on the SCSI chain (or
removing the SCSI card) seems to help reduce frequency of the problem.

     A nearly certain fix is inserting a 3.5" diskette into Drive 1
before or just after power-up. This usually forces recognition of 3.5"
diskette drives and enables correct functioning.

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


011- 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. (Replacing a blown ULN2003
should not be too difficult. Both Mouser and Newark carry the IC.)

 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.

___________________________



From: Rubywand

012- In connecting a second Disk II drive to my Disk II card I
     misaligned the connectors. The result upon turning it on was a
     static-like clicking noise. Now I can't load anything from
     disk. Is the Disk II card dead? Are the IIe and Drives all
     right?

     Try removing the drive which was connected incorrectly. If your system
boots from the remaining drive (connected in the Drive One position), this
is a fairly good indication that the Disk II card and IIe are okay and that
the removed drive is messed up.

     If it looks like a drive is bad, remove the cover and inspect the
drive's main circuit board for blown components. If nothing obvious shows
up, a decent fix try is to replace the 74LS125 IC on the drive's main
circuit board. (Also, see Q&A 013.)

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


From: Ryan Underwood

     I accidentally offset a row of pins on the //e disk controller card
when plugging one of the drives in. Snap, crackle... you get the picture. I
opened up my freshly fried Disk II, and in the center of the board there is
a 74LS125 that is blown. Replaced it (it was socketed) with the same chip
from another Disk II, and voila! it works again.

     I would reasonably assume that misaligning the drive connector on the
controller is what blew the 74LS125 in several Apple II drives before they
got to me. Note that while the genuine Apple Disk II simply lights the LED
and doesn't move the head at all when this IC was blown, a Mitac drive
actually ate disks. So any number of dead Apple II drives with different
symptoms could have a blown 74LS125.

___________________________



From: Rubywand

013- Last night a sound like a shotgun going off came from my 5.25"
     Disk ][ drive. Now it doesn't work. How can I fix it?

     The noise was probably an electrolytic capacitor exploding. Sometimes,
these develop internal shorts, heat up, and blow (kind of like a sealed can
of beans on a campfire).

     The fix is to remove the drive cover and replace the blown capacitor.
(Look for a small can-like component with goo and/or shredded foil coming
from it.) Circuit board markings should help identify the component. Here
are some suggested replacement values:

C2 (on +12V line):  220uF-500uF at 20V-50V
C4 (on +5V line):    470uF-500uF at 10V-25V
C5 (on -12V line):  10uF-50uF at 20V-50V

     If there is some difficulty identifying the blown capacitor, replace
it with a 500uF unit rated at 20V-50V.

     Before removing the bad capacitor, note which lead is connected to the
outside 'can' part and mark the circuit board where this lead is connected.
This is the Negative side of the capacitor. When installing the new
capacitor make sure its negative lead goes to the marked point on the
circuit board.

____________________________



From:  Wayne Stewart

014- Recently I picked up two 3.5" drives at a swap meet-- a
     Uni-disk and a Laser 128 drive. I've tried cleaning the
     heads; but, neither works with my IIc. What's the problem?

     The 3.5 UniDisk won't work on the earlier IIc unless the IIc has had a
ROM upgrade. The Laser 3.5 is actually a Macintosh drive with the addition
of an eject button. It isn't compatible with any Apple II unless it has a
special controller card, which of course a IIc doesn't.

____________________________



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 sh

aring 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,
includi

ng 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 d

b-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' in

sertion 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 ][
     controller 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: FF if 13-sector; 00 if 16-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)

____________________________



From: Rubywand

019- I would like to add a Read/Write indicator to my Disk ][
     drive. How can I do this with a bi-color LED?

     The circuit described below works well. It shows Red for Drive Enabled
+ Write and Green for Drive Enabled + not Write. That is, a Read is assumed
if the drive is ON and no Write is occurring. The advantage of this
approach is that you always have a lighted LED 'drive ON' indicator and,
so, there is no need to drill a new hole in your drive panel. The new LED
can use the hole occupied by the old "in Use" indicator LED.


Parts

IC-     74121 or 74LS121 1-Shot multi-vibrator
Qgreen- 2N2222A gen purpose NPN transistor
Qred-   2N2222A gen purpose NPN transistor
Rcath-  120 Ohm 5% 1/4 watt resistor
Rgreen- 3.3k 5% 1/8 watt resistor
Rred-   3.3k 5% 1/8 watt resistor
Rp-     20k 5% 1/8 watt resistor
Cp-     10uF/10v 10% "dipped tantalum" capacitor
LED-    2.2V 20ma 3-lead (common cathode) Green/Red bi-color LED


Building the Circuit

IC- locate pin-1 and mark it on bottom side with white-out.
 'Dead-bug' mount the IC using epoxy in the open area near
  top-middle of board with pin-1 end pointing to the right.

connect Rcath to solder pad at - (minus) end of C2
connect #20 wire from IC pin-7 to solder pat at - end of C2

connect Rp from IC pin-11 to IC pin-14
connect Cp + to IC pin-10 and Cp - to IC pin-11

connect #20 wire from IC pin-14 to solder pat at + end of C4

connect a wire from IC pin-3 to end of R16 closest to 74LS125

connect Rgreen to IC pin-1 (74121 "/Q" output)
connect Rred to IC pin-6 (74121 "Q" output)

solder transistor Qred Collector to Q1 power transistor Collector
 (solder pad area at left front of circuit board just to left of
  the power transistor). Position toward left edge of pad.

solder transistor Qgreen Collector to Q1 power transistor Collector
  solder pad to the right of Qred.

LED- connect a 3-wire 11" cable to the LED (black to center, red to
  to lead with right-angle bend, green to lead with slant bend).

Old "in Use" LED- pop off the retainer ring and push through the
  LED. Leave the LED mount in the hole. Cut off the LED, spread
  cable ends and tab over with cellophane tape. (Put old LED and
  ring into parts box.

Spread apart retainer 'leaves' of LED mount (at back side of panel)
  to permit easier insertion of new 3-lead LED.

Run LED + cable over back of board and along bottom toward the
  hole in the front panel. Push through hole. (If hole is too small,
  use a Dremel tool and steel 'bulb bit' to slightly enlarge front
  part of hole.)

connect LED cable black to free end of Rcath
connect LED cable green to Emitter of Qgreen (right transistor)
connect LED cable red to Emitter of Qred.

position old LED cable beneath new LED cable.

connect a wire from the free end or Rgreen (on IC pin-1) to the
  Base lead of transistor Qgreen.

connect a wire from the free end or Rred (on IC pin-6) to the
  Base lead of transistor Qred.

Add epoxy to the back of the LED and holder to secure the LED.



How it Works

     When /Enable goes low to select the Drive, the power transistor (Q1)
switches ON and supplies +12V at its Collector. If there is no Write, 74121
output /Q is high, Qgreen conducts, and the LED shows Green. That is: the
Green LED will light during boots and for any READs.

     If the Drive is selected (/Enabled is low) and there is a Write
operation and Write Protect is not ON, then, the /Write Request signal at
74LS125 pin 8 will go low. This triggers the 74121 One-Shot (at pin 3)
producing an aprox. 160ms pulse at 74121 output Q. For the duration of the
pulse, /Q is low and Q is high. Qred conducts, and the LED shows RED to
indicate WRITE.

____________________________



From: Dan DeMaggio

020- 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 System 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: Benjamin Summers

021- What is a "UniDisk"?

     The UniDisk 5.25 was Apple's replacement for the venerable Disk ][. It
featured an updated design, tan color plastic case, a DB-19 cable, and
daisy-chain port on the back to which other drives could be connected. The
case color was later changed to platinum and the drive was rechristened to
the "Apple 5.25 Drive".

     The UniDisk 3.5 was Apple's first 3.5" drive for the Apple II
line. Like the UniDisk 5.25, it had the DB-19 cable and daisy chain port on
back. UniDisk 3.5 was dropped in favor of the Apple Disk 3.5, a different
design, at the time of the launch of the IIgs.

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


From: Mitchell Spector

     One important difference you forgot to mention: The UniDisk 3.5 was an
"intelligent" drive, whereas the Apple 3.5 was a "dumb"
drive. There was a specialized circuit board inside the UniDisk 3.5 drive
which had its own processor, memory, IWM controller and firmware. This was
needed for the //c, in order for the drive to process data before sending
it on to the machine (which was too slow to do the job by itself). You can
easily spot a UniDisk 3.5 as it matched the snow-white color of the //c and
had i

ts access LED and eject button _above_ the disk insert slot (the Apple 3.5
has them in-line).

____________________________



From: Rubywand

022- What is a "RAM disk"; and, how do I create one on my IIgs?

     A RAM disk is a block of memory which your computer uses like a disk.

     To create a RAM disk on your IIgs ...

o- Boot a ProDOS-8 or DOS 3.3 diskette; or, start your computer with no
boot and press CONTROL-Reset to get to the Applesoft prompt.

o- Press OpenApple-Control-ESC (all three keys at once) to get to the Desk
Accessories menu and select "Control Panel".

o- In the Control Panel menu, select "RAM Disk".

o- Set "Minimum RAM Disk Size" and "Maximum RAM Disk
Size" to the the same value = size of the RAM disk you want. If you
have enough RAM left over to start your operating system and run your
favorite application, a good RAM disk size is 800k.

o- Press Return to set the value. Exit the Control Panel. Exit the Desk
Accessories menu. Turn OFF the computer.

     When you next power up your computer, your RAM disk will be ready to use.

____________________________



From: David Empson

023- Which 3.5" drive/interface combinations work on a IIe?
  
     For the UniDisk 3.5 (model number A2M2053), you need either Apple's
"SuperDrive" card or the "Liron" card. The UniDisk 3.5
is quite rare. It is a clean white color instead of greyish
"platinum". It also has the eject button just above the line of
the disk insertion slot, with a separate manual ejection hole.

     The "Liron" card's official name is "Apple 3.5 Floppy
Disk Drive Interface Card". It has the word "Liron" on the
back (which is the nickname of the IWM disk controller chip, if I remember
right).

     For the Apple 3.5 Drive (model A9M0106 as used on the IIgs), you need
either Apple's "SuperDrive" card or the third party
"Universal Disk Controller" card. The drive is platinum in color
and has the eject button in line with the disk insertion slot and the
ejection hole is in the middle of the button.

     The "SuperDrive" card's official name is "Apple II 3.5
Disk Controller Card". The card has an LED on top, and has its own
processor, RAM and ROM.

     For the Apple SuperDrive, you need the "SuperDrive" card.
Model ID is inconsistent. Check for something like "Family number
G7287".

     The SuperDrive looks exactly the same as the Apple 3.5 Drive. It
supports 1.44 MB high density and 720 KB double density disks as well as
the 400 KB and 800 KB formats. You can use a SuperDrive with the Universal
Disk Controller card, but you won't be able to use its extra capabilities,
and it will behave like an Apple 3.5 Drive.

____________________________



From: O Aaland and Michael Pender

024- How can I boot from my /RAM5 RAM disk? All the files are there
     but it just beeps at me and says 'check startup device'!?

     For the RAM disk to be bootable, you need to do a whole-disk copy of a
same-size bootable diskette to the RAM disk. Or, you can initialize* the
RAM disk before you copy files to it or do an install.

*Note: To initialize the RAM disk, click on the RAM disk icon to select it.
Then, click on "Disk" on the menu bar and select
"Initialize". Follow the prompts to init the disk.

     Finally, in the IIgs Control Panel, go to Slots and set Startup Slot
to "RAM Disk".

____________________________



From: Ryan Underwood

025- My 5.25" drive ruins every disk I insert. How can I fix it?

     Probably, the drive's Write signal is ON when it shouldn't be. This
happens with some 5.25" drives when a 74LS125 IC on the drive's
circuit board is blown. (I accidentally offset a row of pins on the //e
disk controller card when plugging in a drive and blew the IC.)  I removed
the drive cover and replaced the 74LS125-- it was socketed-- voila! it
worked again. (For possible disk-trashing fix for DuoDisk drives, see
Q&A 006.)

____________________________



From: Beverly Cadieux

026- I have a 3.5" UniDisk drive on my GS that has performed
flawlessly for years. Recently, when I try to save a file to
a diskette, I get a 'Disk Full' message; but it isn't full.
This happens with other diskettes, too. What's going on?

     There is a known problem when attempting to save an Appleworks file to
a 3.5" UniDisk drive when the disk in the drive is write-protected. It
ruins the disk for future use, and you can't save to it any more. If you
try to save to that disk again later, the situation you describe will
happen.

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


From: Mark R. Percival

     Perhaps the cable has come loose at the back of your IIgs or there is
some buildup of corrosion on the pins. I had a similar problem with an
Apple 5.25" drive once that ended up beng that. Try unplugging your
drive and making sure the contacts are clean and then plug it back in.
--- SBBSecho 2.12-Win32