No IRQ for graphic card in Windows 95

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Franc Zabkar

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I have two 486/586 machines running Win95B. One has a Cirrus Logic VLB
graphics card based on a CL-GD5428 chipset, the other has an S3 Trio
V64+ PCI card. The latter card has a 2-pin interrupt header which I
have jumpered, and I have also enabled "assign IRQ to VGA" in the BIOS
setup.

Neither machine assigns an IRQ to its graphics card. It appears that
these cards are polled, much like standard (non-EPP/ECP) parallel
printer ports which also don't get an IRQ in Device Manager.

OTOH, my Win 98SE box does assign an IRQ to its PCI card (Diamond
Stealth III S540). Is this normal behaviour? FWIW, both motherboards
have UMC chipsets.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

What software are you still using that requires an IRQ for VGA? You should
be able to update it to a later product.
--
Jeff Richards
MS MVP (Windows - Shell/User)
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:qajh94hkd8r645v2j5juroq41q8f7c71v0@4ax.com...
>I have two 486/586 machines running Win95B. One has a Cirrus Logic VLB
> graphics card based on a CL-GD5428 chipset, the other has an S3 Trio
> V64+ PCI card. The latter card has a 2-pin interrupt header which I
> have jumpered, and I have also enabled "assign IRQ to VGA" in the BIOS
> setup.
>
> Neither machine assigns an IRQ to its graphics card. It appears that
> these cards are polled, much like standard (non-EPP/ECP) parallel
> printer ports which also don't get an IRQ in Device Manager.
>
> OTOH, my Win 98SE box does assign an IRQ to its PCI card (Diamond
> Stealth III S540). Is this normal behaviour? FWIW, both motherboards
> have UMC chipsets.
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

Been awhile but,,, is it an updated 95B? IF so check to ensure the driver
has 95 support. You may find the older drivers work better than the newer.

PnP (and IRQ assignment) wasn't that great in 95 [or that era] so you may
want to manually assign IRQs by SLOT or EDGE in the BIOS, then check the
Device for any setting adjustments.
Older 486 machines had limited BIOS support... early 586 (Socket 5/7) BIOSs
were also somewhat limited.
The VLB card MAY be difficult to get set properly.

What motherboards are we talking about?

--
MEB
http://peoplescounsel.orgfree.com
--
_________



"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:qajh94hkd8r645v2j5juroq41q8f7c71v0@4ax.com...
| I have two 486/586 machines running Win95B. One has a Cirrus Logic VLB
| graphics card based on a CL-GD5428 chipset, the other has an S3 Trio
| V64+ PCI card. The latter card has a 2-pin interrupt header which I
| have jumpered, and I have also enabled "assign IRQ to VGA" in the BIOS
| setup.
|
| Neither machine assigns an IRQ to its graphics card. It appears that
| these cards are polled, much like standard (non-EPP/ECP) parallel
| printer ports which also don't get an IRQ in Device Manager.
|
| OTOH, my Win 98SE box does assign an IRQ to its PCI card (Diamond
| Stealth III S540). Is this normal behaviour? FWIW, both motherboards
| have UMC chipsets.
|
| - Franc Zabkar
| --
| Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:qajh94hkd8r645v2j5juroq41q8f7c71v0@4ax.com...
>I have two 486/586 machines running Win95B. One has a Cirrus Logic VLB
> graphics card based on a CL-GD5428 chipset, the other has an S3 Trio
> V64+ PCI card. The latter card has a 2-pin interrupt header which I
> have jumpered, and I have also enabled "assign IRQ to VGA" in the BIOS
> setup.
>
> Neither machine assigns an IRQ to its graphics card. It appears that
> these cards are polled, much like standard (non-EPP/ECP) parallel
> printer ports which also don't get an IRQ in Device Manager.
>
> OTOH, my Win 98SE box does assign an IRQ to its PCI card (Diamond
> Stealth III S540). Is this normal behaviour? FWIW, both motherboards
> have UMC chipsets.
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.

In reference to the parallel port, you may mean that the standard port is
not assigned any DMA designation. In any case, should not be assigned a
hardware irq.
--
Dave
 
Re: No IRQ for graphic card in Windows 95

On Wed, 6 Aug 2008 00:20:28 -0400, "MEB" <meb@not here@hotmail.com>
put finger to keyboard and composed:

>Been awhile but,,, is it an updated 95B? IF so check to ensure the driver
>has 95 support. You may find the older drivers work better than the newer.
>
>PnP (and IRQ assignment) wasn't that great in 95 [or that era] so you may
>want to manually assign IRQs by SLOT or EDGE in the BIOS, then check the
>Device for any setting adjustments.

The only available option is to choose edge triggered or level
triggered interrupts, but it makes no difference either way.

>Older 486 machines had limited BIOS support... early 586 (Socket 5/7) BIOSs
>were also somewhat limited.
> The VLB card MAY be difficult to get set properly.

The datasheet for the CL-GD542x chip shows the chip's IRQ pin as being
tristate-able which means it can be turned off. This pin goes active
when the "CL-GD542x has reached the end of an active field.
Specifically, the transition occurs at the beginning of the bottom
border."

So it appears that the graphics card only uses the IRQ pin to signal
when it is about to scan the last line of each frame. Maybe the driver
doesn't need to know this and therefore doesn't bother assigning an
IRQ ???

> What motherboards are we talking about?
>
>--
> MEB
> http://peoplescounsel.orgfree.com

The AMD 5x86 board is a "4IP-UMC-AIO" and uses a UMC UM8881F/UM8886BF
northbridge/southbridge plus a UM8663BF/UM8667 Super I/O chipset.

The 486 board is a Biostar MB1433/40/50UIV with a UMC498 chipset
(according to the BIOS ID).

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Wed, 6 Aug 2008 07:36:25 -0500, "Lil' Dave"
<spamyourself@virus.net> put finger to keyboard and composed:

>"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
>news:qajh94hkd8r645v2j5juroq41q8f7c71v0@4ax.com...

>>I have two 486/586 machines running Win95B. One has a Cirrus Logic VLB
>> graphics card based on a CL-GD5428 chipset, the other has an S3 Trio
>> V64+ PCI card. The latter card has a 2-pin interrupt header which I
>> have jumpered, and I have also enabled "assign IRQ to VGA" in the BIOS
>> setup.
>>
>> Neither machine assigns an IRQ to its graphics card. It appears that
>> these cards are polled, much like standard (non-EPP/ECP) parallel
>> printer ports which also don't get an IRQ in Device Manager.
>>
>> OTOH, my Win 98SE box does assign an IRQ to its PCI card (Diamond
>> Stealth III S540). Is this normal behaviour? FWIW, both motherboards
>> have UMC chipsets.
>>
>> - Franc Zabkar
>
>In reference to the parallel port, you may mean that the standard port is
>not assigned any DMA designation. In any case, should not be assigned a
>hardware irq.

My understanding is that a standard 8-bit unidirectional, 8-bit
bidirectional, or 4-bit nibble mode bidirectional parallel port does
not get an IRQ or a DMA resource. In fact I have removed the IRQ
jumper for my SPP port and it still works. OTOH, an EPP port gets an
IRQ but no DMA, while an ECP port gets both an IRQ but no DMA.

See http://www.beyondlogic.org/spp/parallel.htm

"The Parallel Port's interrupt request is not used for printing under
DOS or Windows. Early versions of OS-2 used them, but don't anymore."

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Wed, 6 Aug 2008 09:35:32 +1000, "Jeff Richards"
<JRichards@msn.com.au> put finger to keyboard and composed:

>What software are you still using that requires an IRQ for VGA? You should
>be able to update it to a later product.

I always thought that interrupts were handled by the driver, not the
application. In any case, neither machine appears to require an IRQ
for its graphics card, but I was just curious as to why not.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Thu, 07 Aug 2008 07:27:04 +1000, Franc Zabkar
<fzabkar@iinternode.on.net> put finger to keyboard and composed:

Sorry that should read ...

"an EPP port gets an IRQ but no DMA, while an ECP port gets both an
IRQ and a DMA."

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

The interrupt handler is installed by the driver, but it's optional and it
is only a very small number of applications that expect the interrupt to
occur, and in almost all cases they will check on startup that the handler
is installed and interrupts are occurring and will usually fail to run if
they aren't. It's to do with synchronising screen updates to the refresh
period. I can't think of any software I've used in a long time that needs
the interrupts, but then I don't play a lot of games.
--
Jeff Richards
MS MVP (Windows - Shell/User)
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:pprh94daipfdgfbn72q6ilbdrs9gepjcj6@4ax.com...
> On Wed, 6 Aug 2008 09:35:32 +1000, "Jeff Richards"
> <JRichards@msn.com.au> put finger to keyboard and composed:
>
>>What software are you still using that requires an IRQ for VGA? You
>>should
>>be able to update it to a later product.
>
> I always thought that interrupts were handled by the driver, not the
> application. In any case, neither machine appears to require an IRQ
> for its graphics card, but I was just curious as to why not.
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Wed, 6 Aug 2008 00:20:28 -0400, "MEB" <meb@not here@hotmail.com>
put finger to keyboard and composed:

>Been awhile but,,, is it an updated 95B? IF so check to ensure the driver
>has 95 support. You may find the older drivers work better than the newer.
>
>PnP (and IRQ assignment) wasn't that great in 95 [or that era] so you may
>want to manually assign IRQs by SLOT or EDGE in the BIOS, then check the
>Device for any setting adjustments.
>Older 486 machines had limited BIOS support... early 586 (Socket 5/7) BIOSs
>were also somewhat limited.
> The VLB card MAY be difficult to get set properly.
>
> What motherboards are we talking about?
>
>--
> MEB
> http://peoplescounsel.orgfree.com

I just checked my old Win95B backups for my current socket 7
motherboard (M571, PCChips). There is no IRQ assigned to the onboard
VGA (SiS 5597/5598). However, the same hardware under Win98SE *does*
get an IRQ. Unfortunately I can't be certain whether "assign IRQ to
onboard VGA" was enabled in the BIOS in both instances.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Thu, 07 Aug 2008 15:32:48 +1000, Franc Zabkar
<fzabkar@iinternode.on.net> put finger to keyboard and composed:

>I just checked my old Win95B backups for my current socket 7
>motherboard (M571, PCChips). There is no IRQ assigned to the onboard
>VGA (SiS 5597/5598). However, the same hardware under Win98SE *does*
>get an IRQ. Unfortunately I can't be certain whether "assign IRQ to
>onboard VGA" was enabled in the BIOS in both instances.

Just checked my BIOS again. The option is actually to "assign IRQ to
PCI VGA". There is no such option for the onboard VGA, so it does look
like Win95 doesn't assign an IRQ to the graphics card.

The drivers are here:
http://driver.sis.com/graphic/igp/5598/5598_113.zip

There appear to be two relevant files, SIS597M.DRV and SIS597M.VXD.
The Win95 and Win98 versions of the former are identical, whereas the
two VXD files are the same size and version, but have different
contents.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

Sorry Franc, attending to other things and went on a short trip,,, will
look at the info once I get caught up on the mail and groups.....

--
MEB
http://peoplescounsel.orgfree.com
--
_________



"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:ppjm94dea1t5moqjef1fl7ena2ib86n6vg@4ax.com...
| On Thu, 07 Aug 2008 15:32:48 +1000, Franc Zabkar
| <fzabkar@iinternode.on.net> put finger to keyboard and composed:
|
| >I just checked my old Win95B backups for my current socket 7
| >motherboard (M571, PCChips). There is no IRQ assigned to the onboard
| >VGA (SiS 5597/5598). However, the same hardware under Win98SE *does*
| >get an IRQ. Unfortunately I can't be certain whether "assign IRQ to
| >onboard VGA" was enabled in the BIOS in both instances.
|
| Just checked my BIOS again. The option is actually to "assign IRQ to
| PCI VGA". There is no such option for the onboard VGA, so it does look
| like Win95 doesn't assign an IRQ to the graphics card.
|
| The drivers are here:
| http://driver.sis.com/graphic/igp/5598/5598_113.zip
|
| There appear to be two relevant files, SIS597M.DRV and SIS597M.VXD.
| The Win95 and Win98 versions of the former are identical, whereas the
| two VXD files are the same size and version, but have different
| contents.
|
| - Franc Zabkar
| --
| Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

Like I said, a long time ago, but I seem to remember some issues with VLB.

Lost Colors with Cirrus Logic Based VLB Video Adapter
http://support.microsoft.com/kb/119874

But personally, seems there WAS some sort of issue with the IRQ [seems like
it was 9 on most video adapter boards when enabled], in addition to the
issues when mixed with PCI slots [as indicated above]. As for the on-boards
I can't remember... however, a tidbit of memory seems to indicate what you
placed elsewhere, the IRQ wasn't really that necessary as the VLB design
addressed in a different fashion.

Couldn't get to the driver for some reason...

There were a few discussion groups on tweaker forums related to the VLB
cards/chips, not sure if any would still pop-up, might try over on
http://www.vintage-computer.com/ or the archives on Tom's Hardware.

--
MEB
http://peoplescounsel.orgfree.com
--
_________



"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:ppjm94dea1t5moqjef1fl7ena2ib86n6vg@4ax.com...
| On Thu, 07 Aug 2008 15:32:48 +1000, Franc Zabkar
| <fzabkar@iinternode.on.net> put finger to keyboard and composed:
|
| >I just checked my old Win95B backups for my current socket 7
| >motherboard (M571, PCChips). There is no IRQ assigned to the onboard
| >VGA (SiS 5597/5598). However, the same hardware under Win98SE *does*
| >get an IRQ. Unfortunately I can't be certain whether "assign IRQ to
| >onboard VGA" was enabled in the BIOS in both instances.
|
| Just checked my BIOS again. The option is actually to "assign IRQ to
| PCI VGA". There is no such option for the onboard VGA, so it does look
| like Win95 doesn't assign an IRQ to the graphics card.
|
| The drivers are here:
| http://driver.sis.com/graphic/igp/5598/5598_113.zip
|
| There appear to be two relevant files, SIS597M.DRV and SIS597M.VXD.
| The Win95 and Win98 versions of the former are identical, whereas the
| two VXD files are the same size and version, but have different
| contents.
|
| - Franc Zabkar
| --
| Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95

On Tue, 12 Aug 2008 02:54:41 -0400, "MEB" <meb@not here@hotmail.com>
put finger to keyboard and composed:

>Like I said, a long time ago, but I seem to remember some issues with VLB.
>
>Lost Colors with Cirrus Logic Based VLB Video Adapter
>http://support.microsoft.com/kb/119874

There is nothing wrong with the adapter except that it occasionally
powers up with a strange "pixellation" issue. A hardware reset usually
cures this. Other adapters with the same chipset have the same
problem.

I did once have a colour problem, but that turned out to be an open
inductor in one of the RGB outputs. This prevented the card from
seeing the corresponding 75 ohm termination resistor in the monitor,
which then caused the CL chip to revert to monochrome mode.

> But personally, seems there WAS some sort of issue with the IRQ [seems like
>it was 9 on most video adapter boards when enabled], in addition to the
>issues when mixed with PCI slots [as indicated above]. As for the on-boards
>I can't remember... however, a tidbit of memory seems to indicate what you
>placed elsewhere, the IRQ wasn't really that necessary as the VLB design
>addressed in a different fashion.
>
> Couldn't get to the driver for some reason...
>
> There were a few discussion groups on tweaker forums related to the VLB
>cards/chips, not sure if any would still pop-up, might try over on
>http://www.vintage-computer.com/ or the archives on Tom's Hardware.
>
>--
> MEB
> http://peoplescounsel.orgfree.com

I originally had a black screen problem with the S3 PCI card.
Reseating it seems to have fixed it. It was only while troubleshooting
this adapter that I noticed its open IRQ jumper. Curiosity prompted me
to find out if the card would behave any differently with the jumper
installed. It seems that it is not really needed, at least not for
word processing.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Re: No IRQ for graphic card in Windows 95





"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:ade6a45g3ct9fq1no6082322i3je2jlq46@4ax.com...
| On Tue, 12 Aug 2008 02:54:41 -0400, "MEB" <meb@not here@hotmail.com>
| put finger to keyboard and composed:
|
| >Like I said, a long time ago, but I seem to remember some issues with
VLB.
| >
| >Lost Colors with Cirrus Logic Based VLB Video Adapter
| >http://support.microsoft.com/kb/119874
|
| There is nothing wrong with the adapter except that it occasionally
| powers up with a strange "pixellation" issue. A hardware reset usually
| cures this. Other adapters with the same chipset have the same
| problem.

Well, I do remember difficulties with the VLB format, in that it was
difficult at times to get good connections via the slot. But if your's is
on-board I'd think maybe the connector cable was going bad or one of the pin
connections might be loose. I get that even today with this monitor... the
dang cable stresses the connections and either breaks the soldered joints
[generally IN the monior], or the pins expand causing intermittent issues.
Right now its decided to darken one side (right) while there is a "bleed" of
light stripes from dark colors like black to the right... ah well, some day
I might actaully fix it again.

|
| I did once have a colour problem, but that turned out to be an open
| inductor in one of the RGB outputs. This prevented the card from
| seeing the corresponding 75 ohm termination resistor in the monitor,
| which then caused the CL chip to revert to monochrome mode.

OH yeaaaah, had issues like that on occasion.

|
| > But personally, seems there WAS some sort of issue with the IRQ [seems
like
| >it was 9 on most video adapter boards when enabled], in addition to the
| >issues when mixed with PCI slots [as indicated above]. As for the
on-boards
| >I can't remember... however, a tidbit of memory seems to indicate what
you
| >placed elsewhere, the IRQ wasn't really that necessary as the VLB design
| >addressed in a different fashion.
| >
| > Couldn't get to the driver for some reason...
| >
| > There were a few discussion groups on tweaker forums related to the VLB
| >cards/chips, not sure if any would still pop-up, might try over on
| >http://www.vintage-computer.com/ or the archives on Tom's Hardware.
| >
| >--
| > MEB
| > http://peoplescounsel.orgfree.com
|
| I originally had a black screen problem with the S3 PCI card.
| Reseating it seems to have fixed it. It was only while troubleshooting
| this adapter that I noticed its open IRQ jumper. Curiosity prompted me
| to find out if the card would behave any differently with the jumper
| installed. It seems that it is not really needed, at least not for
| word processing.
|
| - Franc Zabkar
| --
| Please remove one 'i' from my address when replying by email.

--
MEB
http://peoplescounsel.orgfree.com
--
_________
 
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