Apple SCSI cables and terminators
| Apple SCSI cables and terminators | |
|---|---|
.png) |
|
| The SCSI System Cable, Peripheral Interface Cable and Cable Extender (Apple, Tape Backup 40SC Owner's Guide, 1988) | |
| Manufacturer | Apple Computer |
| Type | SCSI cables and terminators |
| Interface | DB-25 Macintosh SCSI port; 50-pin Centronics-type SCSI connector |
| Compatible | Macintosh Plus and later Macintosh models with a DB-25 SCSI port; Apple IIe and IIGS with an Apple II SCSI card; Apple SCSI peripherals |
| Model | M0206, M0207, M0208, M0209, M3503LL/A, M5871G/A |
The Apple SCSI cables and terminators are the parts of the Apple SCSI Cable System, which connects external SCSI devices to a Macintosh or to an Apple II SCSI card. The desktop Macintosh SCSI port is a DB-25 socket, and Apple's external SCSI devices have 50-pin connectors.[1] The cable system was documented in Apple's manual The Apple SCSI Cable System, part number 030-2042-B.[2] The total length of cable on the bus must not exceed 20 feet (6 metres).[3]
| Product | Order number | Service and engineering numbers | Ends |
|---|---|---|---|
| SCSI System Cable, 18 in | M0206 | 658-8031 or 590-0305 (smoke), 590-0345 (beige) | DB-25 male to 50-pin male |
| SCSI System Cable, 6 ft | M3903LL/A | – | DB-25 to 50-pin |
| SCSI Peripheral Interface Cable, 3 ft | M0207 | 658-8034 or 590-0306 (smoke), 590-0346 (beige) | 50-pin male to 50-pin male |
| SCSI Cable Extender, 3 ft | M0208, later M0208LL/B | 658-8033 or 590-0307 (smoke), 590-0347 (beige) | 50-pin male to 50-pin female |
| DB-25 to DB-25 SCSI Cable | M5557LL/A | – | DB-25 to DB-25 |
| SCSI Cable Terminator | M0209 | 658-8032 or 590-0304 (smoke), 590-0344 (beige); platinum 590-0695-A | 50-pin, pass-through |
| SCSI Cable Terminator II (black) | M5871G/A | 590-0695-B, 590-0705 | 50-pin, pass-through |
| SCSI Active Terminator | M3503LL/A | 922-1185 (service), 590-0772-A (moulded) | 50-pin, pass-through |
| SCSI Passive Terminator | M0332LL/A | – | 50-pin |
Numbers for the first-generation parts are from Apple's Peripheral Interface Guide; the M-numbers added later, and the 6-foot and DB-25 cables, are from Apple's 1996 cable data sheet; the terminator part numbers are from Apple's Tech Info Library.[3][4][5][6] The HDI-30 cables for the PowerBook are covered on Apple PowerBook cables.
Macintosh SCSI port
[edit | edit source]| Pin | Signal | Pin | Signal | Pin | Signal |
|---|---|---|---|---|---|
| 1 | REQ/ | 10 | DB3/ | 19 | SEL/ |
| 2 | MSG/ | 11 | DB5/ | 20 | DBP/ (parity) |
| 3 | I/O/ | 12 | DB6/ | 21 | DB1/ |
| 4 | RST/ | 13 | DB7/ | 22 | DB2/ |
| 5 | ACK/ | 14 | Ground | 23 | DB4/ |
| 6 | BSY/ | 15 | C/D/ | 24 | Ground |
| 7 | Ground | 16 | Ground | 25 | TERMPWR |
| 8 | DB0/ | 17 | ATN/ | ||
| 9 | Ground | 18 | Ground |
The connector on the computer is a DB-25 male. Pin 25 carries terminator power, which the Macintosh Plus and the Macintosh Portable do not supply.[3] The PowerBooks do not supply it either.[7] The Portable leaves it out to save the battery, so devices on a Portable must be switched on and stay on.[8]
The port uses the same DB-25 shell as an RS-232 serial port, but it is a parallel bus. Never plug an RS-232 device or cable into it. A serial printer plugged into the SCSI port of a Macintosh Plus can damage the SCSI chips, and Apple's repair is a new logic board.[3][9]
SCSI System Cable
[edit | edit source]The SCSI System Cable connects the first external device to the computer. It is 18 inches long, with a DB-25 male plug for the computer and a 50-pin male plug for the device.[1][3] Apple lists it for Apple IIe and IIGS computers with an Apple II SCSI Card or High-Speed SCSI Card, every Macintosh except the 128K, 512K and 512K Enhanced, and the Hard Disk SC, Tape Backup 40SC, AppleCD SC, LaserWriter II SC, Personal LaserWriter SC and Apple Scanner.[3] A 6-foot version (M3903LL/A) was on sale by 1996.[4]
| DB-25 | Signal | 50-pin | DB-25 | Signal | 50-pin |
|---|---|---|---|---|---|
| 1 | REQ/ | 49 | 14 | Ground | 1, 2, 3 |
| 2 | MSG/ | 46 | 15 | C/D/ | 48 |
| 3 | I/O/ | 50 | 16 | Ground | 4, 5, 6 |
| 4 | RST/ | 45 | 17 | ATN/ | 41 |
| 5 | ACK/ | 44 | 18 | Ground | 7, 8, 9, 11 |
| 6 | BSY/ | 43 | 19 | SEL/ | 47 |
| 7 | Ground | 16, 18, 19 | 20 | DBP/ | 34 |
| 8 | DB0/ | 26 | 21 | DB1/ | 27 |
| 9 | Ground | 20, 21, 22 | 22 | DB2/ | 28 |
| 10 | DB3/ | 29 | 23 | DB4/ | 30 |
| 11 | DB5/ | 31 | 24 | Ground | 23, 24, 25 |
| 12 | DB6/ | 32 | 25 | TERMPWR | 38 |
| 13 | DB7/ | 33 |
The pin pairs are Apple's cable chart; the signal names are those of the Macintosh port.[3] The chart prints the cable number as 568-8031 on its second panel, a misprint for 658-8031.[3]
SCSI Peripheral Interface Cable
[edit | edit source]The Peripheral Interface Cable joins one external SCSI device to the next. It is 3 feet long with identical 50-pin male connectors, which Apple describes as recessed and lined with gold ribbon pins.[1] It is wired straight through, pin 1 to pin 1 and so on, except that pins 10, 12 to 15, 17, 35 to 37, 39, 40 and 42 are not connected.[3][10]
SCSI Cable Extender
[edit | edit source]The Cable Extender lengthens a System Cable or Peripheral Interface Cable. Apple's Tape Backup guide gives it as 3 feet long. One end has a connector like a device's socket, with protruding contacts and SCSI clips, which takes the plug of the cable being extended; the other end has a recessed plug like those on the other cables, which goes to the next device or to a terminator.[1] Apple's peripheral guide calls it male to female.[3] Apple's support article says extenders are typically 1 metre long.[10] It has the same straight-through wiring and unconnected pins as the Peripheral Interface Cable.[3][10]
Apple's figures for length vary by article. The Peripheral Interface Guide and the AppleCD SC Plus manual limit the whole chain to 20 feet.[3][11] A 1991 article gives 2 metres (about 6 feet) as the most between two devices, or 18 feet with a single device on the bus.[12] The extender article allows up to 7 metres (21 feet) between two devices using several extenders.[10]
Faster machines are less tolerant of poor cable. For the Quadra 800 and other models with the 53C96 SCSI chip, Apple specifies cables with an impedance of 90 to 130 ohms, shielding, and every data line twisted with a ground. A mixture of different external cables can make the bus erratic, and the disk directory damage it causes can keep producing failures after the cables are replaced.[13]
SCSI terminators
[edit | edit source].png)
A SCSI bus must be terminated at both ends. Apple's internal hard disks carry terminating resistor packs, so with an internal disk the computer end of the bus is already terminated; Apple's external SCSI devices have no terminators of their own.[1][14] The Macintosh logic board is not terminated, except on the Macintosh IIfx.[15]
SCSI Cable Terminator
[edit | edit source]The Cable Terminator is a 50-pin plug that passes every pin straight through and terminates each signal line. Each signal pin is connected to terminator power (pin 38) through a 220-ohm resistor and to its own ground pin through a 330-ohm resistor; pin 11 passes straight through and nothing more.[16] The pairs, ground pin first, are 1-26, 2-27, 3-28, 4-29, 5-30, 6-31, 7-32, 8-33, 9-34, 16-41, 18-43, 19-44, 20-45, 21-46, 22-47, 23-48, 24-49 and 25-50.[16] That article gives the terminator's part number as 590-0348, a number not in Apple's peripheral guide, which lists 590-0304 and 590-0344.[16][3]
Apple's article on building a 25-pin terminator uses the same values on the DB-25 port's signal lines: 220 ohms to TERMPWR (pin 25) and 330 ohms to ground on each.[17]
Black terminator (SCSI Cable Terminator II)
[edit | edit source]The Macintosh IIfx came with a black terminator, officially the Apple SCSI Cable Terminator II. Its faster SCSI hardware is more sensitive to reflections, and the black terminator adds filter capacitance and changes some resistor values.[5] In Apple's schematic, REQ and ACK each have a 470-ohm and a 220-ohm resistor to TERMPWR and 330 ohms to ground; every other line has the usual 220 ohms to TERMPWR and 330 ohms to ground; and TERMPWR is decoupled once by 2.2 µF and 0.01 µF capacitors.[18] The LaserWriter IIf and IIg need the same black terminator when a hard disk is connected to their SCSI port, and the black terminator works on other Macintosh models too.[19][20]
On a IIfx, use one black terminator at the end of the external chain and no more. Apple warns that more than one can damage the logic board or the device that supplies terminator power. Remove any built-in terminators from third-party external devices. Inside, a IIfx without a hard disk has an Internal SCSI Termination Block (590-4515) plugged into an Internal SCSI Filter (590-4516). When a drive is fitted, the filter goes between the drive cable and the drive, and the termination block comes out.[5]
Active terminator
[edit | edit source]In 1995 Apple replaced the old terminator (service part 658-8032) with the Apple SCSI Active Terminator, M3503LL/A, service part 922-1185. A low-dropout regulator takes the terminator power, normally 4.25 to 5.25 V, down to 2.85 V and feeds 110-ohm termination resistors, which makes it far less sensitive to the terminator power each device supplies. It has no LED, and its regulator runs whenever terminator power is present. The moulded part number tells the two apart: 590-0304-A on the old terminator and 590-0772-A on the active one. No Apple product requires it, and the IIfx and some LaserWriters still need the black terminator.[6] Apple's 1996 data sheet recommends active terminators for AV and faster SCSI devices and passive pass-through terminators for slower ones.[4]
Where to put terminators
[edit | edit source]- With an internal hard disk, fit one terminator to the last external device. With no internal disk, fit a terminator at the first external device, and a second at the last device if there is more than one.[21]
- Use no more than two terminators on a chain. If a third-party device has a built-in terminator, put it at the end of the chain.[11][1]
- A cable left connected to the last device, with nothing at its far end, is still part of the bus; terminate the end of the cable.[22]
- For a single device on a Macintosh Plus, Apple placed the terminator on the device's input, between the System Cable and the device. With more than one device, or more than 10 feet of cable, add a second terminator on the last device's spare port.[23]
- On a Quadra 900 or 950 the internal bus is terminated at both ends already, so internal drives must have their terminators removed. A Quadra 700 without an internal drive needs internal terminator 630-0408, the part designed for the Macintosh Classic.[24]
A device that takes terminator power from the Macintosh can be switched off without disturbing the bus. A device that supplies its own terminator power leaves the bus unterminated when it is off, and the Macintosh may then fail to start.[25][26]
Faults
[edit | edit source]| Symptom | Probable cause | Action |
|---|---|---|
| Macintosh Plus hangs at power-up with a SCSI device attached | The Plus supplies no terminator power | Switch on at least one SCSI device that supplies it[7][2] |
| Macintosh Plus with several drives mounts only some of them | The drives are not ready when the Plus starts | Switch the drives on about 30 seconds before the Plus, and use one type of terminator throughout[27] |
| Macintosh will not start while one external device is switched off | That device supplies its own terminator power | Leave it switched on, or use a device that takes terminator power from the Macintosh[25][26] |
| Macintosh Portable crashes with an external SCSI device attached | The Portable supplies no terminator power | Switch the device on and leave it on; shut down before connecting or disconnecting[8] |
| Macintosh IIfx starts with one external device but not with two | Wrong terminator, or internal SCSI filter missing | Use the black terminator at the end of the chain and check the filter at the internal drive[28] |
| Macintosh will not start with an external drive attached | Drive off at start-up, SCSI ID 0, or a bad cable or terminator | Switch the drive on first, set its ID between 1 and 6, and swap the cable and terminator[29] |
| Last device on the chain cannot be seen, whatever its ID | Impedance of the particular mix of devices and terminators; Apple names the Apple Scanner as prone to it | Change the chain by adding a terminator, a device or an extender cable[30] |
| Quadra 800 starts or mounts its internal disk intermittently | Internal drive on the middle connector of the internal cable, or mixed external cables | Move the drive to the last connector, use matched cables, and reinitialise the disk if its directory is damaged[13] |
| Printer names appear and disappear in the Chooser | Termination problem | Check the termination of the bus the printer is on[31] |
| Macintosh Plus SCSI port dead after a serial printer was plugged into it | RS-232 signals have damaged the SCSI chip | Replace the logic board; use the Mini-DIN-8 serial cable for serial devices[9] |
Related pages
[edit | edit source]- Apple PowerBook cables (HDI-30 SCSI System Cable and SCSI Disk Adapter)
- Hard Drive Maintenance and Repair
- Apple External SCSI Hard Drive, Apple Hard Disk 20SC, Apple Tape Backup 40SC and AppleCD SC
- Macintosh IIfx
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Apple Computer, Apple Tape Backup 40SC Owner's Guide, 030-5631-A (1988), Chapter 1, "SCSI background" and "Organizing your SCSI chain", pp. 3-7 and 10 (PDF pp. 17-21 and 24). Hosted as File:Apple Tape Backup 40SC Owner's Guide (1988).pdf. Supports: the Apple SCSI Cable System of cables and terminators; the DB-25 connector on the System Cable and 50-pin connectors elsewhere; the 18-inch System Cable, 3-foot Peripheral Interface Cable and 3-foot Cable Extender and their connectors; one terminator at each end of the bus; Apple internal hard disks having terminating resistors and Apple external devices having none; attaching only the System Cable to the computer's SCSI port; where to place terminators.
- ↑ 2.0 2.1 Apple Computer, Tech Info Library article 2896, Macintosh Plus Doesn't Provide Termination Power, created 29 April 1988, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the SCSI Cable System manual, Apple part 030-2042-B; the Macintosh Plus not supplying termination power; a drive alone on a Plus failing when it cannot supply termination power itself, and the remedies.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Apple Computer, Peripheral Interface Guide, 7th edition, rev. January 1991. Hosted as File:Apple Service Technical Procedures Peripheral Interface Guide Jan 1991.pdf. Pages as cited: Macintosh Family Computers, Computer Ports, "SCSI Connector", pp. 8-9 (PDF pp. 12-13): pin assignments, total cable length of 20 feet (6 metres), no termination power on the Macintosh Plus or Portable, and the warning against RS-232 devices; Peripheral Connections, p. 25 (PDF p. 29): model and part numbers of the System Cable, Peripheral Interface Cable, Cable Extender and Terminator; Cables, "SCSI Cables", pp. 12-13 (PDF pp. 138-139): System Cable wiring, compatible computers and peripherals, the straight-through wiring of the Extender and Peripheral Interface Cable and the pins not connected.
- ↑ 4.0 4.1 4.2 Apple Computer, Apple Cable Solutions data sheet, October 1996, L02069A, p. 2, "SCSI Connections". Hosted as File:Apple Cable Solutions data sheet (1996).pdf. Supports: the Apple SCSI Active Terminator M3503LL/A, SCSI Passive Terminator M0332LL/A, SCSI Terminator II (Black) M5871G/A, SCSI Cable Extender M0208LL/B, SCSI System Cable M0206, SCSI Peripheral Interface Cable M0207, SCSI System Cable (6 ft.) M3903LL/A and DB-25-DB-25 SCSI Cable M5557LL/A; the data sheet's description of active terminators for AV and faster peripherals and passive feed-through terminators for slower ones.
- ↑ 5.0 5.1 5.2 Apple Computer, Tech Info Library article 5511, Macintosh IIfx: Termination (4/95), created 14 July 1990, reviewed 13 April 1995, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the four external terminators (590-0304; platinum 590-0695-A; black 590-0695-B and 590-0705, about 10,000 of the first), the name Apple SCSI Cable Terminator II; the Internal SCSI Termination Block (590-4515) and Internal SCSI Filter (590-4516); where each goes; using only one black terminator; the warning that more than one black terminator can damage the logic board or the device supplying termination power; Apple external devices having no internal terminators; the IIfx's faster SCSI and the extra capacitance and changed resistor values of the black terminator.
- ↑ 6.0 6.1 Apple Computer, Tech Info Library article 17218, Apple SCSI Terminator: Description of Active Terminator (2/95), created 23 February 1995, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf. Supports: M3503LL/A replacing service part 658-8032, new service part 922-1185; a low-drop regulator taking 4.25 to 5.25 V termination power down to 2.85 V into 110-ohm resistors; always on when termination power is present; no LED; 590-0304-A moulded on the old terminator and 590-0772-A on the new; not required by any Apple product; the IIfx and some LaserWriters still needing the black terminator.
- ↑ 7.0 7.1 Apple Computer, Tech Info Library article 1750, Macintosh Plus SCSI Port: No Termination Power, created 19 February 1986, reviewed 2 July 1992, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: a Plus hanging at power-up unless at least one SCSI device is switched on; most other Macintosh models except the PowerBooks supplying termination power on pin 25; the Plus not supplying it because of power supply limits; the DB-25 SCSI port being for SCSI devices only.
- ↑ 8.0 8.1 Apple Computer, Tech Info Library article 6073, Macintosh Portable: SCSI Termination Problems (1/95), created 31 August 1990, reviewed 21 November 1994, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the Portable not supplying termination power, to limit battery drain; external devices on a Portable having to be powered on; shutting down before connecting or disconnecting; only the IIfx having termination on the logic board.
- ↑ 9.0 9.1 Apple Computer, Tech Info Library article 1687, Macintosh Plus: Serial Printer Damages SCSI Port, created 23 January 1986, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: logic board damage from an RS-232 serial printer plugged into the SCSI port of a Macintosh Plus, the logic board replacement, and the Mini-DIN-8 to DB-25 peripheral cable for serial devices.
- ↑ 10.0 10.1 10.2 10.3 Apple Computer, Tech Info Library article 2691, SCSI Cables: Extenders And Pinouts (4/94), created 1 March 1988, reviewed 5 April 1994, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: up to 21 feet (7 m) between two devices using several Cable Extenders; extenders typically 1 m long; straight-through wiring of the Peripheral Interface Cable and the Cable Extender, with pins 10, 12-15, 17, 35-37, 39, 40 and 42 not connected.
- ↑ 11.0 11.1 Apple Computer, AppleCD SC Plus Owner's Guide (1991), Chapter 2, "About SCSI devices", pp. 10-11. Hosted as File:AppleCD SC Plus Owner's Guide (1991).pdf. Supports: the 18-inch system cable and 3-foot peripheral interface cables; extenders; a total chain length of 20 feet; a terminator at each end; no more than two terminators; Apple external devices without built-in terminators.
- ↑ Apple Computer, Tech Info Library article 7344, SCSI: Maximum Cable Length Between Devices is Six Feet, created 29 April 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ 13.0 13.1 Apple Computer, Tech Info Library article 12852, SCSI Termination and Quadra 800 Performance (7/93), created 27 July 1993, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf. Supports: the internal drive needing to be on the last connector of the Quadra 800's internal cable; mismatched external cables causing erratic operation on 53C96 machines; cables with 90 to 130 ohm impedance, shielding and data lines twisted with ground; directory damage persisting after the cables are replaced; each part testing good alone.
- ↑ Apple Computer, Tech Info Library article 12500, SCSI Terminators: Use at Both Ends of SCSI Chain (7/93), created 1 July 1993, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf. Supports: a terminator at the beginning and end of the chain; the internal hard drive as the terminated beginning; terminating the last or only external device; possible data integrity problems otherwise.
- ↑ Apple Computer, Tech Info Library article 6070, Macintosh SCSI Termination: A Brief Explanation, last reviewed 31 August 1990, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: Macintosh logic boards not terminated; the IIfx without an internal drive shipping with a terminator on the internal connector; terminating the internal drive and the last device; the IIfx with one external device needing the internal terminator and one on the device.
- ↑ 16.0 16.1 16.2 Apple Computer, Tech Info Library article 2223, SCSI Terminator: Description of the connections inside, last reviewed 2 April 1987, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the terminator, Apple part number 590-0348; the straight-through pins; the 330-ohm resistor from each signal to its ground and the 220-ohm resistor to the common terminator-power line on pin 38; the pin pairs; pin 11 straight through only.
- ↑ Apple Computer, Tech Info Library article 3559, 25-Pin SCSI Terminator: How To Build, last reviewed 31 January 1989, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the DB-25 SCSI pinout; each signal line in the Apple terminator connected to TERMPWR through 220 ohms and to ground through 330 ohms.
- ↑ Apple Computer, Tech Info Library article 6748, SCSI Terminator: Black Terminator Schematic, created 6 February 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the schematic of the black terminator 590-0705-A: REQ and ACK with 470-ohm and 220-ohm resistors to TERMPWR and 330 ohms to ground; all other lines 220 ohms and 330 ohms; 2.2 µF and 0.01 µF on TERMPWR at one place only.
- ↑ Apple Computer, Tech Info Library article 9589, LaserWriter IIf and IIg: Black Terminator Part Number (11/94), created 7 January 1992, reviewed 11 November 1994, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf. Supports: the LaserWriter IIf and IIg needing the black terminator used with the IIfx when a hard drive is attached; finished goods part number M5871G/A for the Apple Terminator II (Black).
- ↑ Apple Computer, Tech Info Library article 7787, Macintosh IIfx Terminators: Compatible with Macintosh Family, last reviewed 18 February 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ Apple Computer, Tech Info Library article 2385, SCSI Terminators: Using them with a Macintosh and a SCSI Drive, last reviewed 1 September 1987, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the terminator placement for a Macintosh II or SE with and without the internal 40 MB drive, and for the Macintosh Plus.
- ↑ Apple Computer, Tech Info Library article 3080, SCSI Cable Connection and Termination, created 29 June 1988, reviewed 9 July 1992, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: a terminated System Cable left on a Macintosh with nothing at its far end being acceptable; cables attached to the last device being part of the bus and needing termination at their end.
- ↑ Apple Computer, Tech Info Library article 662, Hard Disk 20SC: Connecting a terminator, last reviewed 30 September 1987, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the difference between the Hard Disk 20SC Owner's Guide and the Apple SCSI Cable System manual; both placements working; the terminator on the input of the first device, and a second on the last device for more than one device or more than 10 feet of cable.
- ↑ Apple Computer, Tech Info Library article 9399, Macintosh Quadra 700, 900 & 950: SCSI Termination Issues 1/93, created 16 December 1991, updated 26 January 1993, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf. Supports: the Quadra 700 internal terminator 630-0408 from the Classic; the gray external terminator 658-8032; the Quadra 900 and 950 internal bus terminated at both ends; removing terminators from internal drives; SCSI IDs 0 to 6 across both buses.
- ↑ 25.0 25.1 Apple Computer, Tech Info Library article 5472, Hard Drive SCSI Termination Power, last reviewed 1 May 1990, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: Mass Microsystems DataPak and early SuperMac DataFrame drives supplying their own termination power; the bus left unterminated when such a device is off; devices using Macintosh termination power being safe to leave off.
- ↑ 26.0 26.1 Apple Computer, Tech Info Library article 7369, Macintosh: Proper SCSI Termination for Powered-Off Devices, created 29 April 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ Apple Computer, Tech Info Library article 7333, Macintosh Plus: Allow 30 Seconds for SCSI Devices to Start Up, created 29 April 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ Apple Computer, Tech Info Library article 7553, Macintosh IIfx: Proper Placement of SCSI Terminators (11/94), created 22 March 1991, reviewed 8 November 1994, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf. Supports: the IIfx failing to start with a second external device; the black terminator in place of the platinum one; checking the SCSI filter between the internal cable and the drive.
- ↑ Apple Computer, Tech Info Library article 8140, SCSI Termination and External Hard Drives, created 14 May 1991, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ Apple Computer, Tech Info Library article 4532, Macintosh: Multiple SCSI Device Startup Problems, last reviewed 13 September 1989, in the archive.org collection APPLE_TIL_ARTICLES, file TIL00001_to_TIL09432.pdf.
- ↑ Apple Computer, Tech Info Library article 9895, Chooser: Disappearing Printer May Be Termination Problem, created 18 February 1992, in the archive.org collection APPLE_TIL_ARTICLES, file TIL09433_to_TIL17062.pdf.