Do ISA Cards lower the performance of a PC ?

**felix99** · 11-03-2002, 06:37 PM

Hi,
I was also thinking of buying a touchscreen overlay for my 5" TFT . But the problem is that I have already used all my com ports ( GPS & IR remote ) so I was thining of putting a ISA card which gives me additional comports an LPT ports into my carputer.
But know like my system is slow i care about performance .

What experiences did you do? Do ISA Cards have imapct on PC performance?

Thanks

Felix

**starfox** · 11-03-2002, 09:41 PM

Afaik (i remember reading something in one of Intel's technical documents on their 440BX chipset), installing ISA cards does decrease system performance, because the board needs to meet more requirements (timing for the ISA bus, watching IRQs, etc).

But i don't know if the performance hit is actually noticable!

Can't you use a PCI card to give you some more com and printer ports? Over here, a PCI card with those costs less than an equivalent ISA card.

**cproaudio** · 11-03-2002, 09:50 PM

You should try the keyspan USA49W USB 4 port serial hub. It gets the power from the USB port, so no AC power adapter needed and no IRQ conflict. Ports are configureable from 2 to 99 I think. It works with my Xenarc touch screen, IRman, Garmin GPS16, ODB-II scanner and serial relay control module. Once the driver is installed, its plug and play. If you want another printer port, maybe try a USB port replicator. It also adds another serial port. With both hub and replicator and your computer, you can have 6-7 serial ports, enough to plug everything you can think of.

**Telek** · 11-03-2002, 09:59 PM

The answer to your question is : maybe.

As to the USB 4port com hub... $$$$... wow

Simply sticking an ISA card into your system should not decrease performace, as it is on a seperate bus... just like your PCI and AGP cards are on their own respective busses. However most ISA cards require the use of I/O ports and IRQs... both of these require the CPU to stop doing anything else that it was doing to service these requests which takes a LONG time to complete (relatively to other CPU operations). Do you remember when hard drives went from PIO mode to DMA? PIO (programmable I/O) mode required the processor to stop to service the data passing between the hard drive and memory, whereas DMA mode allows the data to transfer from the IDE controller directly into memory (hence DMA : direct memory access) without bothering the CPU, thus not slowing down your system.

However with any com ports (or just about any, save for USB coverters) require the use of IO ports and IRQs, but since you're pushing such a small amount of data around you should not notice any difference. Additionally the 16-bit ISA bus can only provide 16MB/s (PCI is 133MB/s and AGP depends on the multiplier, 1x=266MB/s 2x=534MB/s 4x=1068MB/s ...) So 16MB/s *maximum* bandwidth is not much to worry about at all.

Now lets say that you were running an ISA sound card that actually maxxed out the ISA bus, then you might notice a *few percent* slowdown in benchmark tests, but with average use you probably wouldn't notice much at all.

**cproaudio** · 11-04-2002, 03:55 AM

Originally posted by Telek
The answer to your question is : maybe.

As to the USB 4port com hub... $$$$... wow

Yeah It is a bit much but I think it's worth the money. I got mine at www.thenerds.net. They were the cheapest at the time I ordered mine.

**Telek** · 11-04-2002, 03:58 AM

$130 for the 4-port, or you can get 4 single 1-port ones, $10 each and a 4-port USB hub for $15, total cost is $55... less than half the price! You don't have to worry about power for the hub either since the 4 ports can't draw more than 500mA combined anyway.

**MP3DUB** · 11-04-2002, 12:39 PM

The problem with buying 4 individual usb>serial adapters is that many of them only allow one per machine, the driver/translation software wiggs out if you have more.

**cproaudio** · 11-04-2002, 11:58 PM

Originally posted by Telek
$130 for the 4-port, or you can get 4 single 1-port ones, $10 each and a 4-port USB hub for $15, total cost is $55... less than half the price! You don't have to worry about power for the hub either since the 4 ports can't draw more than 500mA combined anyway.

Those cheap $10 ones dont work all that well. Some of them only works with PDAs. I rather have 1 hub and get it over with.

**Telek** · 11-05-2002, 06:59 AM

Shrug... I saw a few models for ~$23 that advertised being able to have up to 99 attached to one system, works with all windows versions win98 and up. Even then, you're still a lot cheaper than using the single 4-port, by almost $30, but I guess it's up to you.

Also, that's assuming that you need 4 extra ports. If you already have 2 on your PC, do you really need a total of 6? Or even if you have done, maybe if you did need a whole extra 4 ports then you can do that route, however if you only need 1 or 2 more, then the hub + individual ones is definitely much much cheaper.

I suppose it depends how much money you have to spend

**cproaudio** · 11-05-2002, 07:29 AM

Garmin GPS16 receiver
Xenarc Touch screen
OBD-II scanner
Serial Relay Control Module
IRman
Cliffnet Alarm control

And yes, I do use all 6 serial devices. 1 on FV24 mobo, 4 on Keyspan 4 port serial hub, 1 on CompUSA's USB port replicator. All works on XP cept Cliffnet as the com control doesnt work with XP yet. The port replicator also adds plug and play PS/2 keyboard and mouse. You dont have to reboot to get the PS/2 KB and mouse to work. It is perfect for those who have wireless KB and mouse. Once the battery dies, pull out the backup corded mouse or KB and plug it in with out rebooting. My system is totally catered for convience.

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