A guy claims to be selling a "dual processor" IIfx

[Unknown_K]

Buyer beware, I ask questions when I am not sure what is included. Bid accordingly.

 

[FerazelX]

$127.50 not too shabby considering it is just a shitty picture of the front of a II/IIx/IIfx box. Seller MUST be an Apple sales rep judging by the selling price and what was shown.

The selling price was in part due to price gouging.

 

[equill]

Do you mean what is usually called 'shill bidding'? That thought did cross my mind when I looked at the bidding list after the auction's end.

de

 

[SiliconValleyPirate]

It's a load of BS, that's what it is. I mean, read the part about the 'Black SCSI Terminator' and tell me he's not full of crap...

 

[Quadraman]

It's a load of BS, that's what it is. I mean, read the part about the 'Black SCSI Terminator' and tell me he's not full of crap...

From LEM

The IIfx requires a special "black" SCSI terminator to accommodate its unusual architecture (see Technote DV 15 for more details).

Tech Note DV 15 located here

http://developer.apple.com/technotes/dv/dv_15.html

One of the features of the now obsolete Macintosh IIfx was a new SCSI chip that provides SCSI data transfer rates up to 3 megabytes per second, faster than any Macintosh model prior to the Macintosh Quadra. To achieve these transfer rates, components on the Macintosh IIfx logic board were smaller and faster, requiring different termination configurations from those of previous Macintosh models.

The Macintosh IIfx requires the use of a combination of the following three new termination parts. Users need to use these parts instead of existing SCSI termination parts to configure a Macintosh IIfx with SCSI devices. The Macintosh Quadra does not require special termination as the Macintosh IIfx does, but it does have some special rules of its own and these are discussed in a later section.

Apple SCSI Cable Terminator II: The Apple SCSI Cable Terminator II is a revised external terminator for the Macintosh IIfx. All finished goods Macintosh IIfx systems ship with this terminator in the box. It is easily recognized because of the black color. Under no circumstances should one use more than a single Apple SCSI Cable Terminator II on an external SCSI chain--doing so may damage the logic board.

Internal SCSI Termination Block: The Internal SCSI Termination Block provides internal termination resistance for Macintosh IIfx systems without internal hard drives. All finished goods systems shipping without internal hard drives have the Internal SCSI Termination Block installed.

Internal SCSI Filter: The Internal SCSI Filter provides termination capacitance for internal Macintosh IIfx hard drives that shipped prior to March 19, 1990. All finished goods systems shipping without internal hard drives have the Internal SCSI Filter installed.

The new termination configurations are simple, and you can remember them with a single rule: Macintosh IIfx systems with external SCSI chains require a terminator at both ends of the SCSI chain. One is internal to the system, while the second is external, located at the end of the chain.

The reason for the new terminator is that on the Macintosh IIfx and future hardware, the SCSI controller chip is a 2 micron part, which makes it very fast. One of the results of this speed is that the chip now thinks that glitches in the /REQ line are real signals. This problem is not likely to occur on all of the Macintosh IIfx machines, but if you have a problem with your hard drive not getting mounted on the new machine, you should try a new terminator first. The symptom is more likely to show up on machines with several (three or more) external SCSI devices attached to the computer and long strands of SCSI cables. Figure 1 illustrates the old-style terminator with the signal showing the spike propagation.

Old-Style Terminator (Gray)

Figure 1 - Old-Style Terminator (Gray)

Basically, if a majority of the data lines change state at once, there is a sudden drain on the TPWR line, which is resistively coupled to all of the lines, including the /REQ line. This sudden drain causes a spike in the line, and this spike is propagated into the /REQ line and to the SCSI controller chip. The newer SCSI controller chip in the Macintosh IIfx interprets this spike as a /REQ signal and starts reading data from the data lines; however, since the data lines need 55 ns to settle, the data that the controller chip reads is junk.

All internal hard disk drives sold by Apple with the Macintosh IIfx and later machines have the Internal SCSI Filter installed; however, most third-party drives do not yet have this filter installed and must be modified by a qualified service provider to work correctly with the Macintosh IIfx.

How to Stop the Terminator

Since the problem is caused by a drop in the TPWR line, the fix is to smooth out the line. One need only add a 2.2 uF capacitor and a 0.01 uF ceramic capacitor as illustrated in Figure 2. These capacitors act like a battery and provide a little extra current when it is needed. This extra current results in a smoother signal, which the SCSI controller chip does not interpret as a /REQ signal.

New-Style Terminator (Black)

Figure 2 - New-Style Terminator (Black)

This new type of filter is only for internal hard disk drives. The Macintosh IIfx ships with a new and improved external terminator (black in color), so hard drive manufacturers do not need to worry about external termination. Apple also ships an internal filter with every Macintosh IIfx that handles the capacitance problem. This internal terminator has two parts. The first is the resistors for the terminator. This part should already be installed on all internal hard disk drives, so it is used only for CPUs that do not have an internal hard drive. The second part of the internal terminator is the capacitor filter. This filter should be installed on the hard disk drive end of the SCSI internal cable. If your hard drive implements the new capacitors, you can, and should, install the capacitor filter--you cannot have too much capacitance.

External Termination

If you manufacture an external SCSI device, do not include termination in it. The only terminator that should be outside a Macintosh IIfx is Apple's external terminator, and it should be at the end of the SCSI chain. If you make a SCSI terminator, it is most likely incompatible and may cause damage to the hardware or the data. If your SCSI device cannot connect with Apple's terminator, then you should provide an adapter that allows your SCSI device to attach to the provided terminator.

Note: A notice in the Macintosh IIfx finished goods box instructs customers to return self-terminating SCSI devices to the service provider to disable termination.

 

[Unknown_K]

I have (2) IIfx units none of which have or need the black terminator. From what I read some of the 1st IIfx systems were noisy and needed that part, the rest were not.

 

[Anonymous Freak]

My IIfx needs one.

Too bad I don't have one.

It will work only with one single internal SCSI device, and that one single internal device can not be a hard drive. No external devices. I have been using a Magneto-Optical drive as the primary drive on it for years.

Of course, that may also be a sign that there is something else horribly wrong with it.