Apple II Hard Drives and SCSI Interface Manual

Csa2 FAQs-on-Ground file: Csa2HDNSCSI.txt  rev012

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 001- How difficult is it to add a hard drive to my IIgs?
 002- What kinds of hard drive systems are available? 
 003- What do SCSI ID numbers mean?
 004- What is "SCSI-2" and how is it different from SCSI-1?
 005- Will a SCSI-2 hard drive work with an Apple II system?
 006- Will my Rev. C SCSI Card work with a SCSI-2 drive?
 007- What is SCSI "termination power"?
 008- Can I avoid the "RamFAST/SCSI is searching SCSI bus" delay?
 009- What is the pin-out for the standard 50-pin SCSI cable?
 010- What's the SCSIHD.DRIVER patch to ignore DRIVER43 partitions?
 011- What is the "bad bug" in the ROM 3.01e RamFAST?
 012- What are correct HS SCSI settings, etc. for a Bernoulli drive? 
 013- What are the settings for a CMS hard drive controller card?
 014- Does it matter when I power-ON my SCSI hard disk?
 015- Can I leave SCSI devices I'm not using turned OFF? 
 016- Is there a generic SCSI tutorial available for downloading?
 017- What is the correct time-out setting for a Focus hard drive?
 018- How do I modify my Apple HSS card to supply Termination Power?
 019- Can I get a Focus drive bigger than a couple hundred MB?
 020- My hard disk is on a CMS SCSI. How do I install System 6.0.1?
 021- How is DMA set for SCSI cards with 8MB RAM cards on the GS?
 022- My 20MB Focus bombs and there's some goo on the card. A fix?
 023- Where can I find the RamFAST manual on the net?

From: Bradley P. Von Haden

001- How difficult is it to add a hard drive to my IIGS?

Adding a hard drive is not much of a problem. Usually, you will need to
insert an interface card, possibly connect a cable or two, and change a
Slot setting in the Control Panel Desk Accessory.


002- What kinds of hard drive systems are available for Apple II

     The most versatile and most common hard drive set-up is an internal
SCSI interface card and an external SCSI drive.  Hard drives, cd-rom
drives, removable media (SyQuest, Iomega), flopticals, and scanners all
can be added to the SCSI chain.  Insert the card in a slot, connect a
cable or two, and change a slot setting.

     The preferred SCSI card is the RamFAST Rev. D SCSI card from
Sequential Systems. The next best card is the Apple Hi-Speed SCSI card.

Here are some RamFAST notes:

- still being produced and supported by Sequential Systems
- faster than Apple Hi-Speed, especially in ProDOS
- provides termination power to the SCSI chain
- allows partitions to be mapped in ProDOS
- device drivers come on the card in the upgradeable ROM chip
- allows up to 8 devices to be added to the chain
- allows up to 12 partitions to be active at any one time
- allows up to 12 partitions per drive
- about $130 new

Here are some Apple High Speed notes:

- no longer produced or supported by Apple
- does not provide termination power to the SCSI chain (can be
  modified to provide termination power)
- does not allow partitions to be mapped in ProDOS
- device drivers are software
- allows up to 7 devices to be added to the chain
- allows over 100 partitions to be active at any one time
- allows up to 20 (?) partitions per drive
- about $110 new (if still available)

For the hard drive itself, look for a SCSI drive in an external
enclosure with the following features:

- 30 day money-back guarantee
- external SCSI ID switching
- dual 50 pin SCSI connectors
- no or switchable termination (use an external terminator at
  end of SCSI chain)
- switchable termination power (on/off) is a plus for users of
  SCSI interface cards which do not supply termination power


From: Rubywand

     Another way to go is a 2.5" IDE drive mounted on an IDE interface
card. This "hard card" plugs into a Slot-- usually Slot 7. Alltech sells
the Focus Hard Card in varying sizes (e.g. 60MB for $99) with system
software installed. SHH Systeme offers the FileCard (about $170 + cost
of drive) as well as a series of IDE controller cards to which you can
add a 2.5" IDE drive (about $120-$170 including mounting kit).

     The IDE hard card approach offers speed and capacity comparable to
SCSI, very easy installation, and, it eliminates hassles with external
boxes and cables. Of course, you will still need to add a SCSI interface
card if you want to connect a SCSI CD-ROM and/or Zip Drive.

Note: If you want your system to include a SCSI CD-ROM drive, it is best
to have a SCSI Zip Drive or SCSI hard disk connected to the SCSI
interface, too. This provides a write-able medium for saving SCSI
interface card setup parms.


From: Rubywand

003- What do the SCSI ID numbers mean?

     SCSI ID numbers identify devices on the SCSI chain. Each device
should have its own, unique ID number in the range 0-7. (If two devices
on the SCSI chain have the same ID number, there will be a conflict and
your system will not function correctly.) Higher numbered devices have
higher priority-- get 'looked for' first-- so, it is standard practice
to set the device you boot from to 6 or 7.

     Most external SCSI devices have a thumbwheel switch, slide switch,
or jumper block on the back to set ID number. Some, like the Creative x2
CD-ROM drive let you click through 0-7. The Zip Drive lets you pick 5 or
6. (By the way, SCSI ID numbers have nothing to do with which Slot the
SCSI interface card is in.)


From: David Empson

     SCSI ID 7 is usually special because the Apple SCSI and Hi-Speed
SCSI cards count as a device set to ID 7 by default (and every Macintosh
has a hard-wired SCSI ID of 7).  The only thing that is special about ID
0 is that it is the standard ID used for an internal drive on a

     There is no problem using SCSI ID 0 on an Apple II. On a RamFAST
SCSI card, it is also safe to use SCSI ID 7 for a drive. The RamFAST
doesn't have a SCSI ID, but every other SCSI card does.


From: David Empson

004- What is "SCSI-2" and how is it different from SCSI-1?

For hard drives, "SCSI-2" basically means that the drive supports a
stricter command set. The physical interface is usually identical.

For other device types, "SCSI-2" means a lot more, because the original
SCSI standard didn't define much in the way of device types and command
sets, so most devices use proprietary command sets. SCSI-2 standardises
the command sets for most types of devices.

There are three special types of interface that you might see mentioned:

 "Fast SCSI" supports data transfer at twice the speed of the  original
SCSI standard (10 MB per second vs 5 MB per second).  This  will not be
a compatibility issue, as it is just the maximum transfer  speed
supported by the drive.  The Apple II cannot transfer more than  one
megabyte per second.

 "Wide SCSI" uses a different cable arrangement to double the width of 
the data path (16 bits instead of 8 bits).  A wide SCSI drive cannot be 
used with an Apple II, unless it can also operated in "narrow" mode
with  the original 50-pin connector.  (There is also "Fast Wide SCSI",
which  doubles the data rate and the width of the bus.)

 "Differential SCSI" involves a different type of interface to the 
computer, where every data signal has a balanced positive and  negative
pair of wires, rather than a single wire and a ground line.  I believe
it has a different type of connector.  Differential SCSI  drives cannot
be used with an Apple II."

Some drives use a proprietary connector, but the standard (narrow,
non-differential) SCSI bus uses the same 50-pin connector for SCSI-1 and

The only significant problem you might run into is termination, and
supply of termination power.  SCSI-2 devices tend to be fussier about
termination than older devices.


005- Will a SCSI-2 hard drive work with an Apple 2 system?

     Usually, yes. I'm on my second Quantum drive that is described as

     There is a major caveat to this answer.  Some newer drives require
a host which implements the arbitration phase of the SCSI communication
dialogue. The RamFAST doesn't do this, and as a result there are some
drives that cannot be used with a RamFAST SCSI card. A notable example
is the Quantum Fireball series. However; the Trailblazer and all older
Quantum models work fine.


006- I have a plain ol' Rev. C SCSI Card, will this work with a
     SCSI-2 drive?

     My Quantum LPS240 is working fine on an original Apple SCSI card.

Note: With the original Apple SCSI card, the card itself is not
terminated, so if you are connecting more than one device, you need to
add a second terminator between the computer and the first drive (using
a "pass-through" external SCSI terminator, or internal termination on
the first drive).


007- What is SCSI "termination power"?

     At least one device (SCSI card or any SCSI drive) must provide
power for the SCSI terminators by feeding 5 volts onto the TERMPWR line
on the SCSI bus.

     Usually, termination power is fed through a diode to prevent
backfeeding from a higher voltage source in case some other device is
also supplying termination power. A good implementation will have a fuse
to protect against shorts and a capacitor to cope with a sudden rise in
termination power drain.

     The Apple SCSI cards do not provide termination power (though some
recent Apple Hi-speed SCSI cards were modified by Apple to provide
termination power).  The RamFAST SCSI card can supply termination power.

     If a drive can supply termination power, I recommend letting it do
so. The TERMPWR line can, in some cases, represent a significant load on
the +5V rail going to the Slots. Both of my Quantum drive mechanisms
provide termination power to the SCSI bus, avoiding the need to supply
it from anywhere else.


From: Rubywand

     On the RamFAST SCSI RevC card, DIP switch #1 is set to ON to supply
termination power. On other RamFAST SCSI cards, a jumper is placed at
JP1 to supply termination power.

     According to RamFAST documentation, it is okay to have the card set
to supply termination power whether or not another device does with a
few notable exceptions. If a connected hard disk (e.g. a Sider drive)
has a sticker saying that the drive supplies termination power and that
the interface must not, then the RamFAST must be set to _not_ supply
termination power.


From: LJSilicon

008- I just reinstalled System 6.01. Now every time I cold boot
     I get this message 'RamFAST/SCSI is searching the SCSI bus
     for devices..etc.' and have to wait several seconds. WEIRD?!

     When you reinstalled the software, the RamFAST set itself for a
long search. This is an option that you can change using the RamFAST
utility. What it is doing is giving your scsi devices a chance to spin
up. If you want a fast check, go to the options menu on the utilities
and reset the Short Timeout option there to "YES".


From: David Empson

009- I would like to make my own SCSI cable. Does anyone on csa2
     know the pin-out for the standard 50-pin SCSI cable?

     The cable pinout is documented in the technical reference manual
for the Apple High-Speed SCSI card (and the original one as well).

This pinout is not a simple mapping from one end to the other.

I repeat that it is NOT easy to make one of these yourself.  Apart from
any issues of wiring errors, you also need a properly shielded cable to
minimise noise being picked up or radiated.  You should definitely not
use a ribbon cable.

Here is the pinout, assuming I haven't made any typos (I can't see any).

DB-25   50-pin     Function

1       49         -REQ
2       46         -MSG
3       50         -I/O
4       45         -RST
5       44         -ACK
6       43         -BSY
7       16,18,19   Ground lines
8       26         -DB0
9       20,21,22   Ground lines
10      29         -DB3
11      31         -DB5
12      32         -DB6
13      33         -DB7
14      1,2,3      Ground lines
15      48         -C/D
16      4,5,6      Ground lines
17      41         -ATN
18      7,8,9,11   Ground lines
19      47         -SEL
20      34         -DBP
21      27         -DB1
22      28         -DB2
23      30         -DB4
24      23,24,25   Ground lines
25      38         TERMPWR

The unlisted pins in the 50-pin connector (10, 12, 13, 14, 15, 17, 35,
36, 37, 39, 40, 42) are ground.

Note: the numbers for the 50-pin connector are counted along each row,
like a DB-25.  They are NOT the wire numbers in a ribbon cable.


From: Steve Reeves

010- Is there some patch for SCSIHD.DRIVER to make it ignore
     APPLE_DRIVER43 driver partitions?

     Yes; you can change the counter in the string comparison routine
that checks for the "Apple_Driver" partition type string so that it only
checks the first 12 characters.  This counter is at byte $3574 in the
System 6.0.1 SCSIHD.DRIVER file and is originally $1F.  Change this to
$0B and the driver will then ignore "Apple_Driver43" partitions.

     If you make this or any other patch to the driver, I also you
recommend you bump up the version number.  Change byte $01FF from $10 to
$2E (for version 6.02 experimental).


from Harold Hislop

011- Someone told me there's supposed to be a bad bug in the
     ROM 3.01e RamFAST. What is it?

     Don't use the built in backup/restore in 3.01e!!! The restore
opeation will nuke the partition map on the drive being restored to, as
well as all existing partitions on that drive!


From: Bradley VonHaden

012- What are correct HS SCSI settings, etc. for a Bernoulli drive? 
     My system is as follows:
     ROM 1 Apple //gs
     4mb AE RAM card
     8mhz ZIP GS
     Apple High-Speed SCSI card
     90 mb Bernoulli hard drive
     System 6.0.1

Three things I can think of to check:

One possibility is DMA compatibility.  If your memory card is not DMA
compatible, then switch 1 on the Apple HS SCSI card should be open (up).

Another possibility I guess is a SCSI ID conflict.  The Apple HS SCSI
card's ID at the factory is set to 7.  Here are the Apple HS SCSI card
switch combinations:

 note1: Switch 1 controls DMA; open (up) turns DMA off
 note2: Switches 2-4 control SCSI card ID
 note3: 'U' means open (up), 'D' means closed (down),
        'z' means Set for correct DMA (see note1)

 SWITCH:     1234  1234  1234  1234  1234  1234  1234  1234
 CARD ID:      0     1     2     3     4     5     6     7

Third, the scsi chain needs termination power to work properly.  This is
different from termination.  Both are required for a properly
functioning scsi chain.  It is possible that neither the Bernoulli drive
nor the Apple HS SCSI card is supplying termination power.  If this is
the case, and there is no other device on the scsi chain to supply said
power, it probably won't work.  There is a modification (requires
soldering skills) to the Apple HS SCSI card to make it supply
termination power.


From: Jack Countryman IAC

013- I want to configure a CMS hard drive controller card to run a
     20 meg drive for a //e. Could someone supply info on settings?

     According to the CMS manual, page D3, the six sets of eight pairs
of jumpers
(u1....u6) are for the following purpose:
   /                                                               |
  /     u 1          u 2            u 3            u 4       j2    |
 /                                                                 |
/                                                                  |
|                                                                  |
|                                                                  |
|                                                                  |
|                                                                  |
|                                                                  |
|    u 5     u 6                                                   |
|___________________________________________                    j1 |
                                            |                      |

u 1: Boot Scan delay....manual shows no jumpers here in default

u 2: first (left) jumper is 'Enable I.C.P. (Yes/No)', middle 6 not
     used, last (right) is 'multiple initiators (Yes/No)'...manual
     shows no jumpers in default configuration

u 3: Selection phase time out delay....I believe this sets how long
     the card waits for the drive to come up to speed(?)...manual
     shows the default as having 4, 5, and 7 with jumpers installed

u 4: Arbitration phase time out delay....manual shows default as no
     jumpers installed

u 5: Bus Free phase time out delay...manual shows default as jumper
     on number 1

u 6: Interrupt recovery delay....manual shows jumpers on 3, 4,
     and 5

     J1 and J2 are single sets of pins. The manual says J2 is not used,
but J1 is to be jumpered.

     The card I have here, came out of a IIGS where it was hooked to
first a twenty meg CMS drive, and later a forty meg CMS drive.  It has
the following jumpers set:

u1:  jumper on 7
u2:  no jumpers
u3:  jumpers on 4, 5, and 7
u4:  no jumpers
u5:  jumper on 1
u6:  jumpers on 3, 4, and 5
j2:  no jumper
j1:  jumper

     As I recall, this setup yeilded a rather long pause for the hard
disk to come up to speed (about 40 to 45 seconds) that we found
necessary at the time to avoid boot problems.


From: B.J. Major

014- Does it matter when I power-ON my SCSI hard disk?

     From the Apple IIgs Owner's Reference, page 267:

"In order for the Finder to recognize a hard disk, the hard disk must be
switched on and up to speed before you start up (or restart) the
computer. Switch on the hard disk, wait about 10 seconds for it to come
up to speed, and then restart the computer."

     From the Macintosh User's Guide for desktop Macs, page 216:

"IMPORTANT:  Always turn on any external SCSI devices connected to your
Macintosh before turning on the computer itself.  Otherwise, your
computer cannot recognize the SCSI devices."


From: Randy Shackelford

015- Can I leave SCSI devices I'm not using OFF when I
     turn ON my GS?

     If it were not okay, I would have fried plenty of hardware. I do
this all the time. I have seen no problems with having some devices off.
As I have mentioned, I keep my magneto optical off most of the time;
and, my buddy who uses my 700 now has a flatbed scanner and leaves it
off most of the time. Both work fine.


From: Daniel L. Miller

Related FAQs Resources: R008SCSITUT.TXT (text)

016- Is there a generic SCSI tutorial available for downloading?

     Yes. Bus signals, commands, etc. for the Small Computer Serial
Interface are described in the text resource file R008SCSITUT.TXT .


017- What is the correct time-out setting for a Focus hard drive?

From: Rubywand

     Supposedly, the purpose of having the Focus spin down and stop
after 2, 10, or whatever minutes of idleness is to prevent over-heating
and unnecessary wear. After a few days of trying various TO settings, I
set my "Time Out" to "Never" and have had no problems with over-heating
or crashes even after many all-day sessions.


Related FAQs Resources: R009HSSTMOD.GIF (GIF pic)

018- How do I modify my Apple Hi-Speed SCSI card to supply
     Termination Power?

     The Apple High Speed SCSI Termination Power modification consists
of adding a diode. It is shown in resource file R009HSSTMOD.GIF from
Harold Hislop and Dan Brown.

The pic shows a simple sketch of the back of the Apple High Speed SCSI
card near connectors 26-33. The directions say that you connect a 1N914
diode between two points:

The anode (non-banded end) of the diode goes to the *top* of L1. The
cathode (banded/striped end) of the diode goes to the >bottom< of RP2

The pic shows the *top* of L1 to be a solder pad (just a solder pad with
no trace showing) a little ways up from a point between connectors 32
and 33.

The >bottom< of RP2 is just a bit up and to the left of the *top* of L1.
It is the lowest of several points (the pic shows 8) arranged in a
vertical column and should have a trace going off to the left.     


From: Scott G

019- Can I get a Focus drive bigger than a couple hundred MB?

   Get a 40MB Focus Hard Card from Alltech.  Get an 800MB IDE 2.5"
Quantum GO-drive from Computer Shopper sources for pennies.  Replace the
original drive on the Focus Hard Card with the big one (VERY easy and
self-explanatory, just use a screw driver).  Low level format,
partition, and high level format. That's it!


From: Gary Black

020- On my ROM-03 GS the hard disk is connected to a CMS SCSI card.
     How do I install System 6.0.1?

     It turns out that the SCSI drivers that come on the Sys 6.0.1
Install Disk downloaded from are incompatible with CMS ver
3.0 (and probably earlier) SCSI cards.

     What I did was to replace scsi.manager and scsihd.driver in the
System 6.0.1 Install disk SYSTEM/DRIVERS folder with scsi.manager,
scsihd.driver, AND CMS.driver from the CMS Utility disk.

     With the replacement scsi drivers installed, the Install disk
recognizes the hard drive and installation went smoothly from that
point. (The CMS files are dated 1989 and 1990, so they are a bit older
than the 6.01 files, which are dated 1993. But, they work!)


From: Scott G

021- How is DMA set for SCSI cards with 8MB RAM cards on the GS?

     DMA needs to be turned off with the Apple HS SCSI card or the
RamFAST revision C card.  It does not need to be turned off with the
RamFAST revision D card (differentiated by being half sized).  All
Sequential Systems RamFAST cards are revision D as are late model CV
Tech cards.  It is the RamFAST revision D that is designed to DMA into
any RAM card, even 8MB models. It was made around the time of the CV RAM
8MB model that turned into Sequential's RAM GS Plus, but functions just
as well with the Sirius card.


From: Louis Cornelio

022- My 20MB Focus bombs and there's some goo on the card. A fix?

     The goo is leaking from the drive due to a failed seal which seems
to plague some of the older Conner drive modules. The fix is to check
with the seller of the drive for a replacement. At Alltech, a good Apple
II person to contact is Tony Diaz.


From: Joe Walters

023- Where can I find the RamFAST manual on the net?

     You can find it at several sites:

Plain text on-line readable at ...

In a .SHK and/or binscii file at ...