Click here to Skip to main content
15,113,726 members

Welcome to the Lounge

   

For discussing anything related to a software developer's life but is not for programming questions. Got a programming question?

The Lounge is rated Safe For Work. If you're about to post something inappropriate for a shared office environment, then don't post it. No ads, no abuse, and no programming questions. Trolling, (political, climate, religious or whatever) will result in your account being removed.

 
GeneralRe: I just noticed I missed my CP birthday! Pin
Nagy Vilmos20-Apr-18 1:56
professionalNagy Vilmos20-Apr-18 1:56 
GeneralRe: I just noticed I missed my CP birthday! Pin
S Houghtelin20-Apr-18 3:01
professionalS Houghtelin20-Apr-18 3:01 
GeneralRe: I just noticed I missed my CP birthday! Pin
RJOberg20-Apr-18 3:47
professionalRJOberg20-Apr-18 3:47 
GeneralRe: I just noticed I missed my CP birthday! Pin
Daniel Pfeffer20-Apr-18 6:28
professionalDaniel Pfeffer20-Apr-18 6:28 
GeneralThought of the Day Pin
OriginalGriff19-Apr-18 6:17
mveOriginalGriff19-Apr-18 6:17 
GeneralRe: Thought of the Day Pin
lopatir19-Apr-18 6:23
Memberlopatir19-Apr-18 6:23 
GeneralRe: Thought of the Day Pin
W Balboos, GHB19-Apr-18 6:31
mveW Balboos, GHB19-Apr-18 6:31 
GeneralArgh! Interrupt problems! Pin
CodeWraith19-Apr-18 6:15
MemberCodeWraith19-Apr-18 6:15 
I have been designing my little 8 bit computer and now have a memory map that should be adequate.
16k ROM
8k RAM (basic RAM if no paged RAM is present, later fixed RAM that should not be paged away)
6k Video RAM
2k I/O registers
32k Paged RAM (32k pages out of up to 16MB)

Nice, huh? NOT!
The 2k for the I/O registers would allow 16 bytes memory space for each of up to 128 I/O devices. No need to overdo it, but I'm going to need about 16 of them. The problem is that at least six of the planned devices will need interrupts. I don't want to poll for keystrokes, mouse events, bytes coming from the IDE port, bytes coming from the serial port, sound chips having empty buffers...

There is an interrupt controller IC, but it will hog up a 4k area in the memory map (which I don't have) at a fixed place where it really hurts (in the 32k paged RAM). This will not help.

Now what will I do? I could simply use an AND gate with enough inputs to unite the IRQs from all devices. When any one of them goes low, the output of the gate will go low and trigger the interrupt.

Nice and well. The processor will call its interrupt routine - and now what? It does not know which device to service. Any ideas?
I have lived with several Zen masters - all of them were cats.

His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.

GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 6:22
mveOriginalGriff19-Apr-18 6:22 
GeneralRe: Argh! Interrupt problems! Pin
CodeWraith19-Apr-18 6:31
MemberCodeWraith19-Apr-18 6:31 
GeneralRe: Argh! Interrupt problems! Pin
lopatir19-Apr-18 6:42
Memberlopatir19-Apr-18 6:42 
GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 6:49
mveOriginalGriff19-Apr-18 6:49 
GeneralRe: Argh! Interrupt problems! Pin
Marc Clifton19-Apr-18 7:32
mvaMarc Clifton19-Apr-18 7:32 
GeneralRe: Argh! Interrupt problems! Pin
CodeWraith19-Apr-18 8:03
MemberCodeWraith19-Apr-18 8:03 
GeneralRe: Argh! Interrupt problems! Pin
Marc Clifton20-Apr-18 3:52
mvaMarc Clifton20-Apr-18 3:52 
GeneralRe: Argh! Interrupt problems! Pin
Slacker00719-Apr-18 6:36
professionalSlacker00719-Apr-18 6:36 
GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 6:50
mveOriginalGriff19-Apr-18 6:50 
GeneralRe: Argh! Interrupt problems! Pin
Slacker00719-Apr-18 7:07
professionalSlacker00719-Apr-18 7:07 
GeneralRe: Argh! Interrupt problems! Pin
lopatir19-Apr-18 7:17
Memberlopatir19-Apr-18 7:17 
GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 7:21
mveOriginalGriff19-Apr-18 7:21 
GeneralRe: Argh! Interrupt problems! Pin
lopatir19-Apr-18 7:36
Memberlopatir19-Apr-18 7:36 
GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 9:27
mveOriginalGriff19-Apr-18 9:27 
GeneralRe: Argh! Interrupt problems! Pin
CodeWraith19-Apr-18 8:13
MemberCodeWraith19-Apr-18 8:13 
GeneralRe: Argh! Interrupt problems! Pin
Marc Clifton19-Apr-18 7:23
mvaMarc Clifton19-Apr-18 7:23 
GeneralRe: Argh! Interrupt problems! Pin
OriginalGriff19-Apr-18 7:27
mveOriginalGriff19-Apr-18 7:27 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.