🚀 go-pugleaf

In article <1993Jan7.122713.17450@walter.cray.com> kelly@spyro.cray.com (Matt Kelly) writes:
>I built a home-brew MIDI interface for my synthesizer setup.  When
>I built it, I had an old PC-XT clone.  I hooked up the receiver
>section of the interface's UART chip (8250) to IRQ2.  This worked
>just dandy.
>
>Now I have a 386-SX system.  IRQ 2 doesn't work anymore.  All docu-
>mentation I have read has said that IRQ2 is a "cascade" interrupt.
>WHAT DOES THIS MEAN, AND HOW DO I MAKE IT WORK????

The PC and XT had one IRQ controller chip, driving the interrupt pin on the
CPU. The AT uses a second IRQ controller, fed through IRQ2 of the first
chip, to signal the CPU. IRQ5 (formerly the HDD controllers IRQ) is now
used by LPT2 (normally!)

>
>In an effort to speed up my success, I rewired the interface so
>that it would use IRQ5 instead of IRQ2.  Still no interrupt response.
>
>I took the software I was using on the old system (which I wrote),
>and re-compiled the .ASM files which handle the interrupts so that
>they would use IRQ5 instead.  Total death.
>
>Any help would be appreciated.  The system I have is a Goldstar with
>2 serial, 1 parallel, 1 game port, 40 meg HD, 2 floppy drives, VGA.

What IRQ is the game-port on?


--
--- Kiz (aka Ian Stuart) istuart@nyx.cs.du.edu
	{ Chivalry is not dead! - Just the Horse }

In <1993Jan7.122713.17450@walter.cray.com> kelly@spyro.cray.com (Matt Kelly) writes:
>HELP!!!!

>I built a home-brew MIDI interface for my synthesizer setup.  When
>I built it, I had an old PC-XT clone.  I hooked up the receiver
>section of the interface's UART chip (8250) to IRQ2.  This worked
>just dandy.

>Now I have a 386-SX system.  IRQ 2 doesn't work anymore.  All docu-
>mentation I have read has said that IRQ2 is a "cascade" interrupt.
>WHAT DOES THIS MEAN, AND HOW DO I MAKE IT WORK????

>In an effort to speed up my success, I rewired the interface so
>that it would use IRQ5 instead of IRQ2.  Still no interrupt response.

>I took the software I was using on the old system (which I wrote),
>and re-compiled the .ASM files which handle the interrupts so that
>they would use IRQ5 instead.  Total death.

>Any help would be appreciated.  The system I have is a Goldstar with
>2 serial, 1 parallel, 1 game port, 40 meg HD, 2 floppy drives, VGA.

>Thanks in advance,

>Matt K.
>==============================================================================
>kelly@els.cray.com                   |   Cray Research, Inc.
>                                     |
>Opinions expressed herein are just   |   "The world's fastest supercomputers".
>that.                                |
>==============================================================================

That's "cascade" as in falls into a bunch of pieces.  The IRQ2 was split
at the time of the AT (I think) to provide more interrupts for use.  Eight
bit cards still can't use the bigger numbers, but I understand that the
16bit cards that need interrupts can do so.  

According to my new motherboard's manual, here they are:

IRQ 2	|--IRQ 8	Realtime clock interrupt
        |--IRQ 9	INT 0AH
        |--IRQ 10	Reserved
        |--IRQ 11	Reserved
        |--IRQ 12	Reserved
        |--IRQ 13	Coprocessor
        |--IRQ 14	Hard Disk
        |--IRQ 15	Reserved
       

-- 
__
"Even if you're on the right track, 
you'll get run over if you don't move."  --Will Rogers.

terry@dadstoy.gbdata.com	Terry Stockdale		Houston, Texas

In article <1993Jan9.124633.19036@mnemosyne.cs.du.edu> istuart@nyx.cs.du.edu (Ian Stuart) writes:

>What IRQ is the game-port on?

Game port does not have any IRQ line. It is just a simple polled
device. It has just I/O address 201h, which you can read and write.
Writing to that address resets the flip-flop timers in the card, which
are used for measuring the state of the joystick potentiometers.
By reading the card you get the state of the buttons and flip-flops.



--
Tomi.Engdahl@hut.fi    !  LOWERY'S LAW:
then@snakemail.hut.fi  !  "If it jams - force it. If it breaks,
                       !   it needed replacing anyway." 

In article <zvtTrAsDBh107h@dadstoy.gbdata.com>, zatar@dadstoy.gbdata.com (Terry Stockdale) writes...
> 
>That's "cascade" as in falls into a bunch of pieces.  The IRQ2 was split
>at the time of the AT (I think) to provide more interrupts for use.  Eight
>bit cards still can't use the bigger numbers, but I understand that the
>16bit cards that need interrupts can do so.  
> 
>According to my new motherboard's manual, here they are:
> 
>IRQ 2	|--IRQ 8	Realtime clock interrupt
>        |--IRQ 9	INT 0AH
>        |--IRQ 10	Reserved
>        |--IRQ 11	Reserved
>        |--IRQ 12	Reserved
>        |--IRQ 13	Coprocessor
>        |--IRQ 14	Hard Disk
>        |--IRQ 15	Reserved

IRQ15 isn't exactly "reserved."  At least not to Artisoft.  My LANtastic
Ethernet card had the option of using IRQ2 for 8-bit PC's or IRQ15 for AT
buses.

>>Now I have a 386-SX system.  IRQ 2 doesn't work anymore.  All docu-
>>mentation I have read has said that IRQ2 is a "cascade" interrupt.
>>WHAT DOES THIS MEAN, AND HOW DO I MAKE IT WORK????

The IRQ2 is used by the second interrupt controller.  Interrupts coming
in on IRQ2 are vectored to IRQ9 instead on a PC-AT.  You can leave your
hardware interrupt on IRQ2, but expect the interrupt vector to be IRQ9
on the software side.

-- 
#ifdef TRUE        | Fuzzy Fox (a.k.a. David DeSimone)       fuzzy@netcom.com
#define  TRUE   0  |
#define  FALSE  1  |  "911 Emergency Rescue Service - Can you hold, please?"
#endif             |

Fellow bit-twiddlers,

I'd like to thank everyone who replied to my post, both on the net
and via e-mail.  The information was most helpful.

I solved my problem.  I am using IRQ5.  The reason it didn't work 
when I tried it before is that the interface I built is now connected
to a new synthesizer which sends periodic "active sensing" bytes.
My interface received these and set the INT bit.  By ignoring these
sense bytes in my interface code, I was never clearing the INT bit,
which caused subsequent bytes to generate overrun errors, etc.  

I inserted code to read these sense bytes, acknowledge them, and keep
the input channel clear.  This fixed it!!!!

FYI, I have discovered AT-class machines pretty much use IRQ interrupts
for whatever reason they want -- there is no real "standard".  Some use
IRQ5 for the floppy drive, some for LPT2, some for LPT1, some for VGA,
etc.  This is unfortunate, but a fact of life.


May your bit buckets always be empty!!!

Matt