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1 PassMark ® Software MemTest86™
2 Copyright (C) 2013-2018 PassMark Software
3 All Rights Reserved
8 PassMark's MemTest86 is a standalone memory testing software for x86 computers.
9 MemTest86 boots from a USB flash drive and tests the RAM in your computer for
10 faults using a series of comprehensive algorithms and test patterns.
11 <For more details see the MemTest86 User Guide>
16 - x86 System (Mac and PC)
17 - USB Flash drive (>= 256MB capacity)
20 Creating a bootable USB drive
23 For Linux:
25 1) Insert a USB drive into a USB slot.
26 2) Determine which device the USB drive is assigned as (eg. /dev/sdc).
27 3) As root, use the 'dd' command to write the image to the USB drive. For example,
29 sudo dd if=$USB_GPT_FREE_FILE.img of=<dev>
31 where <dev> is the device the USB key is assigned to. Use the base device (ie. /dev/sdc) not a partition designation (ie. /dev/sdc1).
33 For Mac:
35 1) Insert a USB drive into a USB slot.
36 2) Determine which device the USB drive is assigned as by opening the Terminal and typing the following command:
38 diskutil list
40 3) Unmount all volumes on the USB drive by typing the following command:
42 diskutil unmountDisk [device name]
44 4) As root, use the 'dd' command to write the image to the USB drive. For example,
46 sudo dd if=$USB_GPT_FREE_FILE.img of=<dev>
48 where <dev> is the device the USB key is assigned to. Use the base device (ie. /dev/disk1) not a partition designation (ie. /dev/disk1s1).
50 Warning: all data on the USB key will be lost.
51 Warning Warning: Make sure that the device used in the dd command above
52 is correct!!!
55 Booting the MemTest86 USB drive
57 This USB drive supports dual booting on UEFI and BIOS platforms.
58 Most newer systems are able to run the UEFI version of MemTest86.
59 On machines that don't support UEFI, the older V4 BIOS release of MemTest86
60 will be automatically booted.
62 To boot from the drive you may need to go into your BIOS settings and
63 alter your boot order. Or launch the boot menu at system startup.
64 The methods for doing this will vary depending on your motherboard.
66 To start MemTest86 insert the USB flash drive into the appropriate drive and
67 restart your computer. If running on a UEFI system, the UEFI BIOS must be configured
68 to boot from the device that MemTest86 is installed on. Most systems have an optional
69 boot menu that is enabled by pressing a key at startup (often ESC, F9, F11 or F12).
71 If available use the boot menu to select the correct drive.
72 You may see both the UEFI and BIOS as separate options.
73 Please consult your motherboard documentation for details.
75 On a Mac, you need to hold down the 'c' key while the computer is booting to boot from CD.
76 To boot from USB, you need to hold down the ALT / Option key on the Mac keyboard
77 while powering on the machine.
80 Reclaiming disk space from the USB drive
82 You may have noticed that the MemTest86 USB drive you have created may have lost some
83 disk space and normal formatting will not recover the lost space.
84 For example, this can happen when a UFD contains multiple partitions, such as the
85 MemTest86 image. Formatting will not span across multiple partitions/volume.
86 To erase the partition records and reclaim the whole disk, you will need to
87 zero the MBR.
89 WARNING: THIS PROCESS WILL COMPLETELY DELETE THE DATA ON THE DRIVE
91 For Linux/Mac:
93 1) Insert the USB drive into a USB slot.
94 2) Determine which device the USB drive is assigned as (eg. /dev/sdc on Linux, /dev/disk1 on Mac).
95 3) As root, use the 'dd' command to erase the partition table of the USB drive. For example,
97 dd if=/dev/zero of=<dev> bs=512 count=1
99 where <dev> is the device the USB key is assigned to. Use the base device (ie. /dev/sdc) not a partition designation (ie. /dev/sdc1).
104 All the documentation is included in the MemTest86 User Guide PDF. It can be found under the
105 'help' folder in the USB flash drive.
110 For technical support, questions, suggestions, please check the User Guide or
111 visit our web page at http://www.memtest86.com
114 Ordering / Registration
116 All the details are in our sales information page
121 The PassMark Development team