For the time being, I have a slightly older computer, which thankfully I’ll be upgrading soon. It has an ISA slot which I’m using for an old type 1 SCSI adpater. It’s hooked up to a Zip drive and CD burner. Anyway, I’ve heard warnings that using an ISA slot can slow down your computer. My computer seems to run fine, as far as I’m concerned, but for various reasons I’m taking out my SCSI card. I already have an IDE CD R/RW drive and I just ordered an IDE Zip drive from eBay.
Anyway, after removing the SCSI card, should I be able to expect an improvement in performance? If it helps, a little info on my computer:
FSB - 100MHZ
CPU - Intel Celeron II 1.0GHZ
This question may be hard or imposible to answer, so I’ll understand if nobody has an answer. Sure, I’ll cry and then die a little inside, but I’ll understand.
The mere existence of an ISA slot or ISA device will not slow down your computer at all. When you read/write to the ISA slot then the CPU will end up slowing down considerably as it waits for the data. Your motherboard may have an ISA buffer which will alleviate this a little. It really depends on the design of the chipset on your motherboard, but even with a buffer ISA I/O is slow.
If you were moving a sound card from ISA to PCI I could easily say you will have a performance improvement, but you are moving a CD burner and Zip drive, which are high-latency devices. Again it depends on your motherboard, and also your devices. If they are DMA-capable then you will definitely see an improvement. Otherwise, I am not sure an improvement will be noticeable, but at least you will never have to worry about SCSI driver issues.
I get paid to design things like ISA and PCI cards, so this won’t be difficult at all.
Anyway, having an ISA slot in the computer doesn’t slow the computer down at all when you aren’t using the ISA device. When you do access the device (like your zip drive) what you’ll find is that the ISA bus is slower than an otherwise identical SCSI card on a PCI slot. Quite a bit slower, in fact, if you are doing bulk transfers like copying a large file from one place to another. If you don’t use your zip drive much then it’s probably no big deal. The one thing you would definately want to be concerned about is the possibility of getting a buffer underrun when writing CDs from your burner. The fact that the drive interface is slower means that the data rate on the CD burner will have to be set lower. Since you are replacing the drives anyway this isn’t an issue for you.
If you use something like an ISA modem, the data rate is so slow that the difference in bus speeds compared to something like PCI becomes negligable. A typical modem is going to max out at about 33k bits/sec, or roughly 4k bytes/sec. 4k bytes/sec is going to take about 1 percent of the computer’s time to process, so no matter how much faster you make the interface, you’ll never see a speed improvement bigger than 1 percent. Most PCI modems are what are called “winmodems” which don’t actually have all of the hardware required to be a modem. They have to emulate some of the functions that are missing, and therefore can actually be slower than a plain vanilla ISA modem.
If you aren’t pushing a ton of data, an ISA card won’t slow your system down. Typically the only things that move enough data around to make a difference are video, sound, ethernet, and disk drives.
Actually, I don’t use my SCSI CD burner to burn CDs. I’ve tried it, but apparently it’s too slow (12x8x32), or old, or something, but Nero allways gives me erros, so I allways use my 52x32x52 IDE drive instead. Packet writing (on the SCSI drive) sometimes works, and sometimes doesn’t. But anyway, the SCSI CD burner isn’t a concern.
Yeah, I’ve thought about getting a hardware modem sometimes, but soon, very soon, my wife and I will be switching to DLS (YES!!!)
OK, thanks for the info. So since I really only use the Zip drive, and only from time to time, then when I remove the SCSI adapter, I won’t notice much of a difference. Gotcha.
Note that 10MBit Ethernet is still so slow that ISA network cards have no problem with that speed. So DSL and cable modems don’t really push ISA network cards that much either.
<slight hijack>
I noticed that my computer was taking a long time to boot up, and that even when it was sitting idle it was running at about 25% CPU usage. I had an external zip drive connected to the parallel port, and when I unplugged it – problems gone.
</slight hijack>
Well, I got the drive today, installed it, and when I started my computer back up, it seems to be running a lot faster than before. It’s too early to tell, but I think that the ISA SCSI card was slowing the system down.
Curious thing, the power supply for the SCSI ZIP100 was a floppy connector, but for the ISA ZIP100 it’s a molex connector.
