how to Remember IRQ, I/O etc

borris9

Hello everybody,

i've just finished my A+ OS and HW training and am ready to go and sit my exams. But i still have a problem trying to remember IRQ's, I/O addresses, BIOS beep error code's in my head.
Does any one have a way of easily remembering these, so if a question is asked what is IRQ 11 for example, you could have a way or code or somthing to remember the order.
PLEASE LET ME KNOW IF YOU DO

Tanks

ghaouf

i do not know any way to know them except to memorize them

kesjw

sorry i agree with "ghaouf" the only way to remember is to memerize until u get it Why not just try saying each one at least 3 times until you finally get it. (thats what i did)

BobbyZ_UK

The best way I find is to come up with some crazy mnemonics

You know that IRQs go from 0 to 15 so construct a sentence (the crazier the better) taking the first letter of the device and matching it to the number

EG

0 S (system timer)
1 K (keyboard)
2 C (cascade from 9)

I know someone called Sue who keeps cats.....so I use Sue Keeps Cats...and so on

It sounds really weird but works (for me anyway)

Give it a try

lazyart

I have the IRQs commited to memory (which is kinda silly because the list is nearly obsolete). Probably the best way to do it is to start with 2 or 3, memorize them, then add a couple after a few days.

For the I/O addresses, do this:

323232

then

ffee77

then fill the last line with 8s:

323232
ffee77
888888

reading vertically downward, you have in order:

com1,com2,com3,com4,lpt1,lpt2

BIOS beep codes (borrowed elsewhere from this forum)..the number in the list corresponds to the number of beeps:

"SMacK For Coming Home Naked"
(or, I prefer)
"Slap My Knees For Coming Home Naked"

System board, Memory, Keyboard, Floppy, CMOS, Hard Drive, Network.

Original post: http://www.techexams.net/forums/viewtopic.php?p=122

I'm sitting Thursday (6/26) for Core. Salivating in the meantime.

Good luck!

bellboy

i started by learning them like the multiplication tables, then i wrote them down. actually with irq, i recalled them better by writing them from 0 to 7 and 15 back to 8.

working with windows 95 helps know them when you use legacy hardware because of the configuration you have to do. it made me glad that i retained my old p133 and got some adapters from ebay to mess with

Wyldstar

I think the best way to memorize them is just to write them on paper over and over again until you're so sick of doing it you can't possibly forget them .

- WS

w^rl0rd

Flash cards! Also, remember that the COM and LPT ports' IRQs are numbered backwards. For example:

COM1 - IRQ 4
COM2 - IRQ 3

LPT1 - IRQ 7
LPT2 - IRQ 5

Also, you know that IRQs 2 & 9 are cascaded and IRQs 10-12 are reserved.

As for I/O adresses, there is a pattern for those too. Just make some flash cards with these column headings and you will see:

IRQ Default Function I/O Address
0 System Timer 40h
1 Keyboard 60h
2 Cascade -
3 Default COM2 (external modem), COM4 2F8h, 2E8h
4 Default COM1, COM3 3F8h, 3E8h
5 LPT2 / Sound card * 278h
6 Floppy drive 3F0h
7 LPT1 378h
8 Real time-clock 70h
9 Cascade / USB -
10 Open for use -
11 Open for use -
12 PS/2 mouse * -
13 Math coprocessor F0h
14 Primary hard drive controller 1F0h
15 Secondary hard drive controller 170h

* Optional

trick000

I think it's helpful if you know how to read hexadecimal.
For example the I/O address for:

IRQ 4
COM1 - 3F8
COM3 - 3E8

IRQ 3
COM2 - 2F8
COM4 - 2E8

I just rank them with com1 being the highest or the first or has priority or however you wanna look at it. Since com 1 is ranked number 1, it is assigned the highest hex value in the group and so on and so forth. This also works for the LPT I/Os and the HD controller I/Os.

LPT1 - 378
LPT2 - 278

Primary HD - 1F0
Secondary HD - 170

That's how I remembered. As for the IRQs I just memorized them and remembered what shinobi was talking about (numbered backwards).

Also, what really helps is if you see them all the time on practice exams.

Webmaster

trick000 wrote:

Also, what really helps is if you see them all the time on practice exams.

Great idea

I will create a separate quiz with only IRQs/DMAs/IO addresses, which you can use to drill yourself.

lazyart

trick000 wrote:

I think it's helpful if you know how to read hexadecimal.
For example the I/O address for:

COM1 - 3F8
COM2 - 3E8
COM3 - 2F8
COM4 - 2E8

I just rank them with com1 being the highest or the first or has priority or however you wanna look at it. Since com 1 is ranked number 1, it is assigned the highest hex value in the group and so on and so forth.

COM2 and COM3 are incorrect (swap them).

trick000

lazyart wrote:

COM2 and COM3 are incorrect (swap them).

woops... sorry bout that. edited.

hammer head

I have all the IRQ's and the addresses for COM 1,2,3,4, and LPT1,2 remembered. Do any of the real questions ask for any of the other devices? I hope I can get by with with this!

hammer head

I meant I know all 15 IRQ's plus what is in the other post.

borris9

Tank You all for ur reply.
Its all great advise and i will see which one works best with me.
:P

Webmaster

And if all the above doesn't help you can try the DMA IRQ I/O quiz I promised here.

(be sure to print out the printer-friendly version at the end of the exam)