Re: Some Apple // hardware questions!

[mkelsey@eecs.wsu.edu (Michael Kelsey)]

> Yes.  You can connect up to eight drives to a RamFast SCSI card, seven
> to an Apple SCSI card.  There can be multiple partitions per drive as
> well, though you will run into implementation limits quite quickly.
> 
> The major limits are as follows:
> 
> Original Apple SCSI card: 7 partitions under ProDOS-8, 63 under GS/OS.
> 
> Apple High-Speed SCSI card: 111 partitions under ProDOS-8 (in theory),
> 63 under GS/OS.
> 
> RamFast SCSI card: 14 partitions under ProDOS-8 or GS/OS (as far as I
> know).
> 
> ProDOS-8 itself has a limit of 14 units (logical devices).  One is used
> up for the /RAM volume, and you need one for every other disk drive
> connected to the system (in normal circumstances, two are reserved for
> each slot containing a disk controller).  In most systems, this limits
> you to 11 SCSI partitions assuming you only have one floppy disk
> controller card, or 9 partitions if you have two disk controller cards
> (e.g. 5.25" and 3.5" drives).

Can I mix and match drive/partition configurations?  I currently have
this type of configuration.

[enhanced mainboard]
Slot 1 - SSC [printer]
Slot 2 - SSC [modem/null modem]
Slot 3 - empty
 Aux - Ramworks III compatible [1MB]
Slot 4 - Apple II Mouse
Slot 5 - ThunderClock Plus [?]
Slot 6 - Disk II
Slot 7 - AEC SCSI

An SSC would be sacraficed for a UDC and the AEC SCSI would be replaced
by an Apple HSS or a RAMfast.

Is there some driver I would have to load from the primary drive [slot x,
drive 1 where slot x is the physical slot of the SCSI adapter] in order
to access any additional drives?  With the QRAM //e 1MB card, I have
to load a device driver for using the extended memory under ProDOS.

I am wondering if I could map in slots 1,2,4,5 for this purpose?  Obviously
slot 3 drives 1 and 2 are absorbed by the RAM drives [/RAM and /QRAM]

> As far as hardware compatibility goes: the original Apple SCSI card
> (which is the slowest of the three main ones) works on any Apple II, the
> Apple High-Speed card requires an enhanced IIe or IIgs (and is second
> fastest), and the RamFast works as you noted according to the revision.

For the purpose of the Apple //e, which would you recommend?  I would be
limited by ProDOS 8 to a maximum of 14 devices anyhow [unless I wanted
to rewrite some major portions of code - yikes!]

>> A Macintosh external 800K drive [in good condition] has also come into my
>> possession.

This is a the traditional Macintosh 800K external drive, one you would 
connect to a beige Macintosh.  There is no daisy chain option
on the back and it has no eject button.  A while back I remember seeing
this exact model connected to a Laser 128EX.  From the information you've
listed, I would neet to locate a UDC.  Any ideas who carries this 
product and the RAMFast/Apple HSS ?

On a quick note, how would I be able to discern if my current SCSI 
controller supports DMA?  The manual was put together ad-hoc, basically
photocopied [with a color cover] and stapled.  The performance is quite
good, nowhere as fast as RAM, but I have never found myself waiting
any length of time for programs to load.  I mention this since I saw
another post with someone who had a SCSI controller w/o DMA and they
mentioned it wasn't much faster than a 3.5" drive.  I realize that
this is a poor example, but Copy II Plus 9.1 loads instantly,
as does Publish-It! 4.0 [overlays disabled].

>> Would it be possible to transfer data between a PC and the Apple //e if I
>> could interface the drive with the Apple?
> 
> Not with the Macintosh 800K drive.  The PC cannot read Apple 400K and
> 800K disk formats, and the Apple II cannot read PC 720K or 1.44MB disk
> formats without the right hardware.

I know Macintosh computers can read 720K PC disks, but is the governed
by the fact they have a SuperDrive?  I guess what it really boils down
to is whether the computer can govern the variable speed of the drive.

> There is no software called "Apple II File Exchange".  Might you be
> thinking of the old Macintosh application (System 6.x through 7.1)
> called "Apple File Exchange"?

I know of Apple File Exchange, but there is a program called Apple II
File Exchange.  Check out

ftp://ftp.wustl.edu/usenet/comp.binaries.apple2/Util/as2fx.6.docs

I have been away from the Apple II arena to immediately know if any
major improvements in Apple II software have occurred.

> Hm.  Assuming you connected a CD-ROM drive to the Apple II (no problem
> with the RamFast, possibly limited choice of CD-ROM drive models with an
> Apple SCSI card), there may be a problem accessing ISO-9660 disks from
> ProDOS-8.  It would require specially written software.

I guess I didn't portray my intents correctly.  I would be using my PC
to transfer any information back to my Apple II, however, if the Apple HSS
and the RAMFast treat SCSI devices as SCSI devices without singling out
which are hard drives, I could use my Plextor 12X SCSI with the Apple II
and write some special software that would interpret the MS-DOS ISO-9660
format.  I wonder, though, how I would be able to access blocks higher
than the 32MB limit?!  Apparently my current SCSI controller [in my Apple]
can, on the hardware level, access higher than 32MB.

> You could get an Apple II Workstation Card (LocalTalk card for the Apple
> II) and connect through an AppleTalk network.

My only concern would be software on the Apple II that would support this
device.  Did Apple ship the Workstation card with software for accessing
file shares? 

Have you seen any transceievers that will interpret between LocalTalk and
Ethernet? 

> Otherwise you are limited to floppies, or the exchange of a hard drive.

I have considered locating the two computers close together and on a single
SCSI bus.  Fortunately on the PC side, configuring the adapter is easy,
and it could be set to some ID that would not conflict the the SCSI ID
of the AEC SCSI interface.  At this point data transfer would be at its best
but I still need to develop some software for reading the PC side [not
too terribly tough].  As long as neither machine writes data at the same
time to the same drive, there shouldn't be any problems.

> Note that the Apple II partitioning scheme (identical to the Mac one) is
> not compatible with the PC's partitioning scheme, so you cannot access
> an Apple II SCSI drive on a PC or vice versa, with standard drivers,
> etc.

Right.  On the Apple II reading blocks of data from a device is a cinch.
On the PC side I haven't found any freeware utilites [of any quality]
that let me read blocks straight from the device.  In this case, the 
"device" equals a SCSI hard drive.

> Either could probably be achieved with add-on software.  There is
> software available to read and write an MS-DOS hard drive on a IIgs, but
> I'm not aware of anything for the IIe.

There is one program, and it only works with a SuperDrive.  It is
restricted to reading the root directory of the media. 

>> GCR versus MFM.  This does seem to be a "neat" avenue for data transfer,
>> however, fruitless based on the phyical incompatibilites of the media.  A
>> while back I formatted an PC diskette, single-sided, single density at
>> 160K.  I wrote an obvious disk pattern, consisting of 0xA0 and a variety
>> of other disk bytes.  I am aware of the Disk II's inability to realiably
>> read zero bytes
> 
> Several consecutive zero bits, in fact (more than two is unrelable).
> The Apple II controller also requires bit 7 set in every disk byte when
> reading.

Yes.  When the tech was last working on my floppy drives, I had him con-
figure the read/write ratio for higher than what was outlined in Apple's
guidelines.  I brought in Essential Data Disk Duplicator and performed
read/write tests during the configuration process.  I have performed
many many many test patterns and drives can write invalid bit patterns.
Even 0x80's are read with Copy II Plus correctly.  I know this will
change as the drive wears with time, but for right now it may help me
investigate this further.

> In theory, maybe.  You could use 4-and-4 encoding on the Apple II (split
> each byte into two, insert bits in place of the zeros in AA), and FM
> encoding on the PC.  This assumes that the bit cells are eight
> microseconds on the PC (four microseconds per clock or data bit), but I
> think they are half as wide.  If so, then even this is not possible.

I seem to recall that the Apple II hardware uses 4usec bit cells and the
PC uses 2usec.

I was considering this avenue.  I'm not sure if I can get the Apple II
to write data correctly to mimic the 2usec bit cells.  Another stumbling
block will be the drive speed.  I haven't found any information that
tells me the tolerance and the drive speed on the PC side.

The Apple drive itself does not require a leading zero in order to read
data.  I confirmed this when research a "bit slip" copy-protection fix.
Various vendors used the "bit slip" technique, and a rare few foolishly
left the expected bit pattern unprotected in their programming.  Others
approached intelligently and manipulated the "read" bit patterns without
making data comparisons.  In the process of determining these hidden bit
patterns, I set up the drive to read bytes without checking for the first
bit set to one.  The "sync bit" patterns were read correctly, with bits of
odd data duplicated [extra ones and zeroes as data was read across the bit
cell].  The Apple II was able to grab three different portions
of a single byte when "bit one" checking was not honored.  This makes me
think that "something" may be possible.

I appreciate all of your information!

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/\/\ichael |<elsey
mkelsey@eecs.wsu.edu
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