A+ 220-1001: Day 4: Firmware, Motherboards & Power Supplies

  1. A+ Certification
  2. A+ 220-1001: Day 1: Intro, Resources & the Test
  3. A+ 220-1001: Day 2: CPUs
  4. A+ 220-1001: Day 3: RAM
  5. A+ 220-1001: Day 4: Firmware, Motherboards & Power Supplies
  6. A+ 220-1001: Day 5: Disks & Mass Storage
  7. A+ 220-1001: Day 6: Peripherals & PC Builds
  8. A+ 220-1001: Day 7: OS Operations, User Management & OS Maintenance
  9. A+ 220-1001: Day 8: Users, Permissions and System Management
  10. A+ 220-1002: Day 9: The Command Line & OS Troubleshooting
  11. A+ 220-1002: Day 10: Displays & Networking Basics
  12. A+ 220-1002: Day 11: LANs: Ethernet & WiFi
  13. A+ 220-1002: Day 12: The Internet & Virtualization
  14. A+ 220-1002: Day 13: Portable & Mobile Computing
  15. A+ 220-1002: Day 14: Mobile Administration & Printing
  16. A+ 220-1002: Day 15: Security & Operations
  17. A+ 220-1002: Day 16: Review & Test Preparation



BIOS == Basic Input Output System: A non-volatile memory chip holds firmware instructions for the lowest-level hardware operations. Motherboard BIOS is universal for a particular model of motherboard.

Check out this excellent online Phoenix BIOS simulator:

CMOS == Complimentary Metal Oxide Substrate: A type of volatile memory chip that holds customized configuration for a particular installation, including the date and time. On older systems a battery preserved these settings – until the battery died, causing the PC to revert back to a truly ancient date.

Boot Option Keys for Windows

These vary by manufacturer.

F2 – Startup check

F10, Escape or Delete (among others) – Enter classic BIOS (this won’t work on most UEFI systems)

F8 – On Windows 7 and earlier, this got you to a Windows Boot Options screen where you could select Safe Mode, etc. Boot Options are available through UEFI on later OSs.

F12 – Boot device selection (boot from USB, CD, DVD etc.)

Getting to BIOS in Windows 7 and Older OSs

Getting to UEFI in Windows 10

Why UEFI instead of BIOS? For One Thing, Bigger Disks

GPT drives vs MBR drives

BIOS vs UEFI Booting, In Depth


Generically, Read Only Memory is non-volatile memory used for BIOS/UEFI and a whole lot of stored-instructions chips.


AT – hard power switch, AT keyboard plug and serial mouse, P8 and P9 mobo power connectors
Google Images

ATX – soft power switch, PS/2 (mini-DIN) keyboard and mouse plugs, 20- or 24-pin block power connectors
Google Images

BTX – parallel slots, processor on the diagonal
Google Images

ITX – Not a single form factor, but a standard for multiple size/form factor motherboards
Google Images

NLX – New Low-Profile Extended, for half-height desktops.
Motherboards and Riser Cards:
Google Images




PCI was the “new” bus that replaced the ISA bus.

It functions like a network switch: every device gets full bus speed, a totally separate communication bus, and “plug and play” auto-configuration.

PCI slots run at 33mhz, 32bits bandwidth, for a total bandwidth (per device) of 133MBps.

There ARE 66mhz PCI buses, though these are rare.

And there ARE 5v and 3.3v PCI slots (which accounts for the different frequencies).

There are also 64bit PCI buses, which use a longer slot: PCI-X.



PCI-Xhttps://en.wikipedia.org/wiki/PCI-X ,
Google Search: PCI-X ,
Google Images: Closeup of PCI-X


Lanes: x1, x2, x4, x8, x16

v1, v2, v3, v4


–> Note that some PCIe lanes may be built into the CPU. Some of these may be used for core interconnects. Other PCIe lanes may be provided externally from the frontside bus (IO) controller.

https://www.google.com/search?q=pcie ,

Old IO: serial, parallel, PCI, old USB, IDE, SATA, ethernet, audio, CMOS

New, fast IO: PCIe (PCI Express), HyperTransport, Infinity Fabric

How Memory Controllers Used to Work


How Memory Controller Buses Work Now




Old ribbon-cable IDE (ATA) drives ran at 33MBps, and used a 40-wire cable.

Later generations ran at 66, 100 and 133 MBps, and required an 80-wire cable (to prevent cross-talk).

First-gen SATA ran at 150MBps, so it wasn’t much of an increase, though management was much easier. You can have SATA RAID, but not IDE RAID.

SATA-2 runs at 300MBps, and

SATA-3 runs at 600MBps.

M.2 Slot Drives

M.2 slots can be used for SSDs, wifi or wireless cards, or any accessory that needs big bandwidth.

M.2 slots can be EITHER:

–> A SATA SSD in an M.2 slot will max out at SATA speeds, i.e. 600MBps maximum.

M.2 slots connect on the back end to either 2 or 4 PCIe lanes (obviously 4 is better).

–> An NVME SSD in an M.2 slot will be hugely faster than SATA, i.e. up to 3500MBps!





Power Supplies

Switching, motherboard interfaces, plugs and maintenance

12v, 5v, 3.3v, 12v ground, 5v ground

P8 and P9 motherboard power jacks for AT mobos
Google Images

20-pin and 24-pin mobo power jacks for ATX and later mobos
Google Images

Dual-legged or multi-legged
Google Images

Modular power supplies
Google Images

Molex plug

SATA plug

Berg plug

PCIe power plugs (6 and 8 wire)

Textbook Time

Chapters 5, 6 and 7