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Eagle 300/500 Upgrade: Hardware Installation

Page 41

Eagle 450 Upgrade Instructions, Rev. A00

6.

Install cabling from any other serial I/O boards to the back panel, following the installation
instructions for the I/O board. If you’re using AM-90 cards for the back panel connections
(which we recommend), insert the bottom AM-90s first and work your way up the back panel.
Make sure pin-1 orientation is correct for all cable connections.

7.

If you have a brace for the serial I/O boards (DWB-20791-00 or -01), install it following the
instructions in PDI-20791-00.

8.

Attach the front panel display cable. If it’s a 26-pin connector, use P9; a 20-pin connector plugs
in at P10.

If you use the 20-pin connector, you should also have four wire pairs which were connected to
the front panel from the AM-319. Attach these to the P8 connector on the AM-138, as follows:

Board Label

Wires

Purpose/Notes

Run

Yellow/White

Run light; white wire goes toward
edge of board.*

Disk

Red/White

Disk activity light; white wire toward
edge.*

Power

Green/White

Power light; white wire toward edge*

Reset

Green/Black

Reset switch

*: If the light does not work in this orientation, reverse the wires.

FINISHING UP

The hardware portion of the upgrade is complete. Continue with Chapter 9 to test and boot the new Eagle
450. Perform these procedures before attaching the computer's cover, in case you need to make some
adjustments.

Once your system completes the testing procedures successfully, shut it off again and reattach the top
cover.

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Содержание AM-1600

Страница 1: ...PDI 03500 21 A00 For Authorized Service Personnel Only Upgrade Instructions AM 1600 or Eagle 100 300 500 to Eagle 450 ...

Страница 2: ...N Il y a danger d explosion s il y a replacement incorrect de la batterie Remplacer uniquement avec une batterie du même type ou d un type recommandé par le constructeur Mettre au rébut les batteries usagées conformément aux instructions du fabricant For AM 3500 E100 E200 E300 E400 E500 and AM 990 01 systems replace battery with Panasonic or Ray O Vac BR2325 only For AM 3500 E550 AM 3500 6000 and ...

Страница 3: ...ives 4 SCSI 2 Dispatcher 4 CHAPTER 3 UPGRADING EAGLE 450 ON BOARD MEMORY 5 ELECTRONIC EQUIPMENT HANDLING PRECAUTIONS 5 INSTALLING THE EXTERNAL CACHE SIMM MODULE 6 INSTALLING MEMORY 7 Setting Memory Jumpers 7 Changing Memory SIMMs 8 CHAPTER 4 CONFIGURING THE AM 138 9 AM 138 BOARD ILLUSTRATION 9 AM 138 Jumpers 11 AM 138 Connectors 12 THE CMOS MENU 13 ETHERNET PORTS 13 REMOTE RESET CAPABILITY 13 INST...

Страница 4: ... 23 REMOVING THE AM 137 BOARD 24 PREPARING THE AM 138 BOARD 26 INSTALLING THE NEW REAR PANEL AND AM 138 26 HOOKING UP THE AM 138 28 FINISHING UP 30 CHAPTER 7 EAGLE 300 500 UPGRADE HARDWARE INSTALLATION 31 PREPARING FOR THE UPGRADE 31 REMOVING THE CHASSIS COVER 31 REMOVING THE ROADRUNNER BOARD 32 Removing a Vertically mounted Roadrunner 32 Removing a Horizontally mounted Roadrunner 35 REMOVING THE ...

Страница 5: ...AND INITIALIZATION FILES 54 BACK UP AND MAKE A NEW WARM BOOT TAPE 54 ADDITIONAL DOCUMENTATION 54 APPENDIX A SCSI TERMINATION 55 SCSI TERMINATION USING EXTERNAL TERMINATOR 55 ATTACHING EXTERNAL DEVICES 56 TERMINATOR POWER 56 APPENDIX B READ AHEAD AND WRITE BUFFERING 57 READ AHEAD 57 Controlling Read Ahead 57 WRITE BUFFERING 58 Potential Pitfalls 59 Setting Up Write Buffering 59 FINAL NOTES 60 ...

Страница 6: ... Figure 7 1 Deskside Chassis Cover Removal 32 Figure 7 2 Roadrunner Mounting Bracket Early Model Eagles 33 Figure 7 3 Roadrunner Removal Early Model Eagles 34 Figure 7 4 Roadrunner Removal Late model Eagles 35 Figure 7 5 AM 319 Mounting Bracket Removal 36 Figure 7 6 Removing the Old Rear Panel 38 Figure 7 7 Eagle 450 Rear Panel 40 Figure 8 1 Deskside Chassis Cover Removal 44 Figure 8 2 Roadrunner ...

Страница 7: ... DOCUMENT This document contains installation instructions for upgrading your computer with an AM 138 board Besides this introduction its chapters include Chapter 2 talks about what hardware and software works with the Eagle 450 upgrade and what doesn t Chapter 3 describes how to install RAM SIMMs and the AM 701 cache board on the AM 138 Chapter 4 covers AM 138 jumper settings and connectors SSD i...

Страница 8: ...er way to do something This indicates a note information which relates to the current topic and may be important for you to remember Text We show characters the computer displays on your screen such as prompts and information messages in this typeface TEXT In examples we use this typeface for the characters you type on your keyboard KEY This symbol tells you to press the indicated key For example ...

Страница 9: ... 50 pin SCSI bus interface the same as on the Roadrunner 030 and 040 Eagles and the AM 4000 The second is a 68 pin Wide SCSI bus interface the same as on the AM 6000 and AM 6060 All devices must connect to one of the two busses the other connector cannot be used You cannot attach peripherals to both busses in the same computer Either SCSI bus will support the SCSI disk and tape devices in your cur...

Страница 10: ...ame bus tends to degrade performance and is not recommended SCSI 2 Dispatcher You must define a SCSI dispatcher in the system initialization command file AMOS uses the dispatcher to communicate with the SCSI controller chip The dispatcher handles all communications with the SCSI controller chip There are two versions of the SCSI dispatcher for the AM 138 board SCZ138 SYS is a high performance vers...

Страница 11: ...propriate place in the upgrade instructions in Chapters 6 7 and 8 Do not attempt install any SIMM until you reach the appropriate place in the installation procedure for your configuration ELECTRONIC EQUIPMENT HANDLING PRECAUTIONS While your computer s hardware is exposed and the AC power cord is unplugged the components are vulnerable to damage caused by static discharge Your body and clothing ar...

Страница 12: ...le is on the notched end of the module see Figure 3 2 below 4 Insert the cache SIMM module into the J12 connector at a slight angle 5 Rotate into the upright position RETAINER CLIP RETAINER CLIP MAKE SURE THIS CURVE IN THE SIMM CARD ALIGNS WITH PIN 1 IN THE SIMM CONNECTOR PIN 1 INDICATOR SIMM CONNECTOR SIMM SINGLE INLINE MEMORY MODULE Figure 3 2 AM 138 SIMM Module Installation The cache SIMM will ...

Страница 13: ...stallation process for your upgrade 1 Insert one SIMM the larger if the SIMMs aren t of equal capacity in connector J10 Align pin 1 at the notched end of the SIMM module with pin 1 on the connector as in Figure 3 2 2 Insert the SIMM module into the connector at a slight angle Rotate into the upright position The SIMM will engage the metal retainer clips and click into position locking the SIMM in ...

Страница 14: ... 64MB X X O O O O 64MB 4MB 68MB X X O X X X 64MB 8MB 72MB X X O O X X 64MB 16MB 80MB X X O X O X 64MB 32MB 96MB X X O O O X 2 x 64MB 128MB X X O X X O 128MB 128MB O X O O O O 128MB 4MB 132MB O X O X X X 128MB 8MB 136MB O X O O X X 128MB 16MB 144MB O X O X O X 128MB 32MB 160MB O X O O O X 128MB 64MB 192MB O X O X X O 2 x 128MB 256MB O X O O X O Table 3 1 AM 138 Memory Module Jumper JP7 Settings Cha...

Страница 15: ...n refer to Chapter 3 AM 138 BOARD ILLUSTRATION Your AM 138 board has been factory tested and shipped with its configuration jumpers set in their standard default positions There are only two areas on the board which may require you to change jumper settings Memory size select JP7 Enabling or disabling the supply of SCSI bus termination voltage JP3 default set at enabled All other jumpers should be...

Страница 16: ...00 Figure 4 1 AM 138 Board Cache SIMM goes here First memory SIMM Second memory SIMM Memory jumpers Serial I O expansion slots On board serial ports Narrow SCSI connector Wide SCSI connector SSD goes here Remote reset adapter attaches here Remote reset jumper ...

Страница 17: ...e When set to FP front panel Turbo switch enables Level7 diagnostic Not user configurable JP3 20 16 IN out Ethernet bus clock select Not user configurable JP5 TERMPWR EN SCSI bus termination voltage EN Enabled DS Disabled User may change JP6 DISC IN Not user configurable JP7 Memory Size Select See Table 3 2 Memory size configuration Installer must configure JP8 32 16 25 20 33 out out out out IN No...

Страница 18: ...10 Bank 0 SIMM First memory SIMM J11 Bank 1 SIMM Second memory SIMM J12 Cache SIMM SIMM AM 701 cache board J13 SCSI 2 Wide 68 pin Cable pin 1 down use keyed cable Cannot use both this and P7 P1 Ports 0 3 40 pin First four on board ports P2 Ports 4 7 40 pin Second four on board ports P3 Power Molex For 5V 12V 12V and GND P4 Power Molex For 5V and GND P5 Option Connector FOR FUTURE USE P6 Program FO...

Страница 19: ...ller so performance is the same with both Use whichever matches your network cabling You cannot use both Ethernet connectors at the same time Attempting to use the Eagle 450 as a gateway between two physical networks will not work To use the AM 138 s Ethernet port you ll need Alpha Micro s networking software AlphaTCP which is included with AMOS 2 3A and later There are two software drivers for th...

Страница 20: ...Attach the adapter s single wire connector to the connector labeled RESET at location P8 Attach it to the pin away from the edge of the board INSTALLING THE SSD CHIP If you are upgrading from an Eagle 100 300 or 500 you must remove the SSD chip from your existing computer and install it in on the AM 138 If you are upgrading from an AM 1600 your upgrade kit includes a new SSD chip which you must in...

Страница 21: ...t panel status display which can show various codes indicating the state of the system Some of these codes will occur only while the computer is booting others may occur any time the computer is running If you have a problem with your computer check the front panel if there is a code displayed look it up in the table in the Eagle 450 Installation and Technical Manual to help diagnose the problem A...

Страница 22: ...If your computer is on a network modify the network configuration file 8 Back up DSK0 and prepare and test a warm boot tape 9 Install the Eagle 450 hardware 10 Turn the computer back on and perform self test 11 Set your CMOS configuration options to match the new system hardware and software 12 Boot up your system Ensure that all peripherals are working correctly The rest of this chapter describes...

Страница 23: ...n how to create a warm boot monitor and a bootable tape You must make a warm boot tape You cannot create a bootable diskette as an emergency boot method The Eagle 450 uses only a SCSI floppy drive and does not support booting from diskettes created on any other type of floppy drive STEP 2 INSTALL THE CORRECT VERSION OF AMOS The Eagle 450 is compatible only with AMOS 2 3A PR 10 98 and later Make su...

Страница 24: ...NTST using the new monitor STEP 5 CREATE A NEW SYSTEM INITIALIZATION FILE You need to make several changes to your system initialization INI file so the computer will boot correctly after you ve installed the Eagle 450 hardware As with the monitor file the CMOS configuration lets you give this file any name you want with an INI extension The steps below create an initialization file called AM138 I...

Страница 25: ...318 0 19200 AM62A 100 100 100 EDITOR 15 VER SCZDSP SCZ138 SYS ET DEVTBL DSK The SCZ138 dispatcher supports several option switches as shown in the following table Switch Description ET Enable tolerant active negation EW EW id Enable Wide SCSI negotiation for all devices Enable Wide SCSI negotiation for SCSI device ID NQ NQ id Disable Command Queuing for all devices Disable Command Queuing for SCSI...

Страница 26: ...ver for the Ethernet interface Remove any line loading the driver for the old CPU board To use the AlphaTCP compatible driver which we recommend in almost all situations use this statement SYSTEM DVR AM138 LDV N To use the AlphaNET compatible driver which is necessary in certain configurations add this statement instead SYSTEM DVR AM138 NDV N The AM 138 supports write buffering for SCSI disk drive...

Страница 27: ...ATA AGAIN Now that you ve installed a new operating system you should make a complete backup of DSK0 and create a new warm boot tape and or bootable floppy disk That way in the unlikely event that you do have to warm boot and restore your disk drive you won t have to repeat the installation of the new operating system If you have an available logical disk device you can copy DSK0 to it rather than...

Страница 28: ...nd clothing are capable of storing an electrical charge that can damage or destroy unprotected electronic components Before you handle any computer hardware make certain your work area is properly protected against static discharge There are a number of commercially available static protection devices like the wrist strap shown in Chapter 3 designed specifically to protect your equipment from harm...

Страница 29: ...7 2 Remove the two male female standoffs on either side of the parallel port connector which attach the AM 137 to the back panel 3 Unplug and label all cables still attached to the AM 137 If you will be using the Wide SCSI 2 bus on the AM 138 disconnect the narrow SCSI cable from all devices and the external connector and remove the cable 4 Remove the two screws attaching the AM 137 s mounting pla...

Страница 30: ...arefully lift the mounting plate up and forward toward the front of the chassis then out The mounting plate helps to stabilize the chassis With it removed you will be able to rock the chassis back and forth slightly This is normal 6 Remove the AM 137 from the mounting plate by unscrewing the nine screws holding it in place 7 If the computer contains an AM 219 floppy controller remove it and the di...

Страница 31: ...he jumpers on the AM 138 board to make sure they are set correctly Refer to the table in Chapter 4 3 Install the cache SIMM DWB 00701 00 at location J12 following the instructions in Chapter 3 4 Install one or two memory SIMMs at J10 and J11 following the instructions in Chapter 3 INSTALLING THE NEW REAR PANEL AND AM 138 1 Remove the five screws attaching the rear panel to the chassis as shown in ...

Страница 32: ...08 to the back of the chassis using the five screws you just removed Leave the screws loose for now 3 Reinstall the CPU mounting plate which now has the AM 138 attached First slide the connector end of the AM 138 into place in the rear panel Then move the other end into the proper orientation and press down over the small locating bumps in the chassis bottom You may have to rock the chassis top sl...

Страница 33: ...lling You must attach the cables to the boards before installing the boards in the AM 138 CAUTION Take care when removing or adding any I O SIMM board Do not force the board into or out of the SIMM connector These connectors are fragile and may break if not handled properly Do not remove or attach an I O cable while the I O board is plugged into the SIMM connector 4 Install any serial I O boards A...

Страница 34: ...Rev A00 8 STANDARD SERIAL PORTS 10 BaseT ETHERNET PORT EXTERNAL SCSI PORT BOOT PORT 0 1 2 3 4 5 6 7 115 9 PIN UPS STATUS PORT 25 PIN PARALLEL PORT 15 PIN AUI ETHERNET PORT NOTE You can use either Ethernet port but not both SERIAL I O EXPANSION SLOTS Figure 6 4 Eagle 450 Rear Panel ...

Страница 35: ...P10 If you use the 20 pin connector you should also have four wire pairs which were connected to the front panel from the AM 137 Attach these to the P8 connector on the AM 138 as follows Board Label Wires Purpose Notes Run Yellow White Run light white wire goes toward edge of board Disk Red White Disk activity light white wire toward edge Power Green White Power light white wire toward edge Reset ...

Страница 36: ... static discharge Your body and clothing are capable of storing an electrical charge that can damage or destroy unprotected electronic components Before you handle any computer hardware make certain your work area is properly protected against static discharge There are a number of commercially available static protection devices like the wrist strap shown in Chapter 3 designed specifically to pro...

Страница 37: ...lly on a special bracket Later model Eagle computers have their Roadrunner boards mounted horizontally on the chassis bottom The screen on the bottom of the chassis has four threaded standoffs designed to the hold the Roadrunner board in place Removing a Vertically mounted Roadrunner The Roadrunner is attached to a mounting bracket on the left side of the computer as you face the computer from the...

Страница 38: ... the DWF 20754 00 bracket shown To remove the board remove these four Phillips head screws You can then fold down the mounting bracket and board assembly onto your work surface to unplug the cables Figure 7 2 Roadrunner Mounting Bracket Early Model Eagles 2 Fold the Roadrunner board and mounting bracket down onto your work surface as shown in Figure 7 3 ...

Страница 39: ...o cables from the X Bus connectors the SCSI cable and the 4 pin power cable Then remove the entire Roadrunner board mounting bracket assembly Figure 7 3 Roadrunner Removal Early Model Eagles 3 Unplug all cables from the Roadrunner board including the SCSI cable power cable X bus cables etc 4 Lift out the entire Roadrunner bracket assembly ...

Страница 40: ... from the Roadrunner board including the SCSI cable power cable X bus cables etc 2 Unscrew the four Phillips head screws holding the Roadrunner to the standoffs and lift the board out 3 Unscrew the standoffs from the screen on the chassis bottom They aren t needed in the Eagle 450 In this configuration the Roadrunner board is mounted on top of four standoffs which are attached directly to the scre...

Страница 41: ... cables SCSI cable and front panel display cable Label the power and display cables as they ll be used in the Eagle 450 If you will be using the Wide SCSI 2 bus on the AM 138 disconnect the narrow SCSI cable from all devices and the external connector and remove the cable 4 Remove the two screws attaching the AM 319 s mounting plate to the chassis as shown in Figure 7 5 POWER SUPPLY 1 2 3 4 5 6 MA...

Страница 42: ...drives are supported with the Eagle 450 PREPARING THE AM 138 BOARD 1 Use eight of the mounting screws you just removed to attach the AM 138 to the mounting plate 2 If you haven t yet check the jumpers on the AM 138 board to make sure they are set correctly Refer to the table in Chapter 4 3 Install the cache SIMM DWB 00701 00 at location J12 following the instructions in Chapter 3 4 Install one or ...

Страница 43: ...F1 F2 G1 G2 H1 H2 PARALLEL 1 PARALLEL 0 ETHERNET E1 E2 Figure 7 6 Removing the Old Rear Panel 3 The new rear panel is smaller so the fan attaches directly to the back of the chassis Use the same four screws to reattach it in the same position it previously occupied 4 Attach the new Eagle 450 rear panel DWF 20753 08 to the back of the chassis using the five screws you just removed Leave the screws ...

Страница 44: ...onnector Attach the connector to the adapter using the provided standoffs If you have narrow SCSI devices you must use a 50 pin to 68 pin adapter PDB 00440 91 to attach each to the wide SCSI cable 3 Attach I O cables to any serial I O boards you ll be installing You must attach the cables to the boards before installing the boards in the AM 138 CAUTION Take care when removing or adding any I O SIM...

Страница 45: ...NDARD SERIAL PORTS 10 BaseT ETHERNET PORT EXTERNAL SCSI PORT BOOT PORT 0 1 2 3 4 5 6 7 115 9 PIN UPS STATUS PORT 25 PIN PARALLEL PORT 15 PIN AUI ETHERNET PORT NOTE You can use either Ethernet port but not both SERIAL I O EXPANSION SLOTS Figure 7 7 Eagle 450 Rear Panel ...

Страница 46: ...tor plugs in at P10 If you use the 20 pin connector you should also have four wire pairs which were connected to the front panel from the AM 319 Attach these to the P8 connector on the AM 138 as follows Board Label Wires Purpose Notes Run Yellow White Run light white wire goes toward edge of board Disk Red White Disk activity light white wire toward edge Power Green White Power light white wire to...

Страница 47: ...performed all of the necessary preliminary processes While your computer s hardware is exposed and the AC power cord is unplugged the components are vulnerable to damage caused by static discharge Your body and clothing are capable of storing an electrical charge that can damage or destroy unprotected electronic components Before you handle any computer hardware make certain your work area is prop...

Страница 48: ...d and the mounting bracket If your AM 1600 does not have a Roadrunner board skip this section and continue with Removing the AM 135 Board This part of the procedure may be easier if you lay the computer cabinet on its right side Make sure your work surface won t scratch the cabinet 1 Remove all cables from the Roadrunner board 2 Four screws attach the Roadrunner to the mounting bracket Remove thes...

Страница 49: ... bracket with screws in these four positions Figure 8 2 Roadrunner Mounting in AM 1600 REMOVING THE AM 135 BOARD 1 Label all cables between the AM 135 and the rear panel then unplug them from both the rear panel and the AM 135 2 Remove the two male female standoffs attaching the AM 135 to the back panel 3 Unplug all cables still attached to the AM 135 or to the AM 986 if your AM 1600 had a Roadrun...

Страница 50: ... AM 135 s mounting plate to the chassis as shown in Figure 8 3 POWER SUPPLY 1 2 3 4 5 6 MAIN ELECTRONICS BOARD MOUNTING BRACKET To remove the board mounting assembly you must remove these two screws Figure 8 3 AM 135 Mounting Bracket Removal 6 Carefully lift the mounting plate up and forward toward the front of the chassis then out The mounting plate helps to stabilize the chassis With it removed ...

Страница 51: ...haven t yet check the jumpers on the AM 138 board to make sure they are set correctly Refer to the table in Chapter 4 3 Install the cache SIMM DWB 00701 00 at location J12 following the instructions in Chapter 3 4 Install one or two memory SIMMs at J10 and J11 following the instructions in Chapter 3 INSTALLING THE NEW REAR PANEL AND AM 138 1 Remove the four screws attaching the fan to the back pan...

Страница 52: ...F1 F2 G1 G2 H1 H2 PARALLEL 1 PARALLEL 0 ETHERNET E1 E2 Figure 8 4 Removing the Old Rear Panel 3 The new rear panel is smaller so the fan attaches directly to the back of the chassis Use the same four screws to reattach it in the same position it previously occupied 4 Attach the new Eagle 450 rear panel DWF 20753 08 to the back of the chassis using the five screws you just removed Leave the screws ...

Страница 53: ...ector Attach the connector to the adapter using the provided standoffs If you have narrow SCSI devices you must use a 50 pin to 68 pin adapter PDB 00440 91 to attach each to the wide SCSI cable 3 Attach I O cables to any serial I O boards you ll be installing You must attach the cables to the boards before installing the boards in the AM 138 CAUTION Take care when removing or adding any I O SIMM b...

Страница 54: ...NDARD SERIAL PORTS 10 BaseT ETHERNET PORT EXTERNAL SCSI PORT BOOT PORT 0 1 2 3 4 5 6 7 115 9 PIN UPS STATUS PORT 25 PIN PARALLEL PORT 15 PIN AUI ETHERNET PORT NOTE You can use either Ethernet port but not both SERIAL I O EXPANSION SLOTS Figure 8 5 Eagle 450 Rear Panel ...

Страница 55: ... plugs in at P10 If you use the 20 pin connector you should also have four wire pairs which were connected to the front panel from the AM 968 Attach these to the P8 connector on the AM 138 as follows Board Label Wires Purpose Notes Run Yellow White Run light white wire goes toward edge of board Disk Red White Disk activity light white wire toward edge Power Green White Power light white wire towar...

Страница 56: ... User s Guide DSO 00156 00 for more information To begin the self test procedure hold the reset button and turn on the computer When the front panel displays 56 press SPACE several times on the boot terminal The CPU will output the results of the self test to that terminal If any problem arises contact the Alpha Micro Technical Assistance Center SET YOUR CMOS CONFIGURATION AND BOOT Once you have c...

Страница 57: ...u need to safeguard your data in the new configuration Use your normal backup procedure to make and verify a complete system backup as discussed in Chapter 5 Then create and test a new warm boot tape and or bootable diskette which reflects the new system configuration If you do not back up your system and make a good warm boot tape you risk losing your data and or having to repeat large portions o...

Страница 58: ...he SCSI bus must be terminated at each end of the cable The AM 138 terminates one end of the bus The other end must be terminated by an active external terminator An active terminator for the SCSI bus you ordered either narrow PRA 00222 21 or Wide PRA 00222 20 is included in your Eagle 450 upgrade kit The AM 138 board is sensitive to incorrect SCSI bus termination If you are using the external ter...

Страница 59: ...e Wide SCSI bus are properly terminated To do so 1 Use an external wide to narrow SCSI cable which actively terminates the high nine lines of the Wide SCSI bus Alpha Micro offers this cable in both three foot and six foot lengths PDB 00440 80 and PDB 00440 81 2 Plug the narrow active external terminator provided with your Roadrunner mounting kit PRA 00222 21 into the unused SCSI I O port of the ex...

Страница 60: ...y execute much faster because the data they require is already in memory and only has to be transferred from the cache into the user partition Programs that do significant random disk access such as RNDRED tend to slow down with this read ahead scheme Most of the slowdown is caused by thrashing of the disk cache where cache entries that will be used again are removed from the cache due to the allo...

Страница 61: ...drive If the program then writes the next sequential block the system must wait the latency time of the drive i e the time it takes the drive to complete one revolution before the next block can be written Latency even on fast SCSI 2 drives is around 7ms Write buffering can speed up the write process When write buffering is enabled all writes to the SCSI disk are first transferred into a buffer If...

Страница 62: ...ty of write buffering it may be worth keeping in mind that the AM 520 disk controller has always used write buffering on a track by track basis however not quite as efficiently as the AM 138 write buffering scheme The SMARTDRV program that comes with MS DOS does write buffering you may have noticed the Waiting for system shutdown message when rebooting a PC with CTRL ALT DELETE and UNIX based comp...

Страница 63: ...ould set up 100K of write buffering for the DSK devices and 100K of write buffering for the SUB device All three drives would have their write buffers flushed every minute or sooner if the drives are not busy with read requests FINAL NOTES Both read ahead and write buffering schemes used on the AM 138 board dramatically improve system performance in our lab tests Both schemes are fine tuned for th...

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