'Legacy-Free' PCs Appearing Everywhere

gjt writes "Finally. The death of of the ISA slot is near. Red Herring is running a story on the Legacy Free PC. Plug all of your mice, keyboards, joysticks, modems, etc. into the Universal Serial Bus. Compaq is releasing a computer called the Vista which will do just that. Yes, Apple did that over a year ago with the iMac and PCI based G3 and G4. Of course, if you're like me, you'd want to build your own box. Asus makes legacy free "PC 99" compliant motherboards. I wonder if this means more IRQ numbers. And what's the state of USB and Firewire support in Linux?" Suddenly USB is everywhere. Will it take hold? A lot of PC manufacturers sure seem to think so.

Comments

Legacy Hardware

[wowbagger]

I'm all for ditching the legacy hardware as soon as possible, but...

Why should a manufacturer eliminate the ISA slots in a computer? If you want to avoid using legacy systems, simply do so, but don't deny me the option!

Here are, as I see it, the problems with doing away with the ISA slots as things stand today:

1. PCI only allows you to have about 4-5 slots without adding a PCI-PCI bridge chip. My two PCI machines have no PCI slots left after:
   1. Video card
   2. 3D card (or two)
   3. Network card
   4. SCSI card
   5. Sound card
   
   In fact, my game machine MUST have an ISA sound card, since the dual V2's, video card, NIC and SCSI take up all 5 PCI slots. If it didn't have ISA, it wouldn't have sound!
   
2. There are a lot of legacy devices out there that are either not going to be available on other busses or shall be so expensive as to not be worth considering. GPIB cards, EPROM burners, certain DSP development boards all come to mind (gosh, what do I do for a living?)
   
3. It is a DAMN site easier to design and prototype an ISA card than a PCI card! Kiss the garage hobbyist goodbye when ISA dies.
   

Now, I do want to address a couple of items I've seen mentioned in this thread about IRQs:

1. First, getting rid of ISA doesn't measurably increase the number of IRQs an x86 machine has. When Intel designed the PC implementation of PCI, they (IMNSHO) screwed up by not putting in a dedicated interrupt controller for the PCI bus. So, even when ISA is dead, 15 IRQs will be the law of the land. Now, by sharing an IRQ among all your USB devices, and another IRQ among all your Firewire devices, and getting rid of COM1-4, LPT1-3, and the mouse, you might make a few more devices available, but unless you cut off all back-compatiblity, you cannot get rid of the keyboard IRQ or COM1.
   
2. The fact that USB "doesn't use an interrupt" and therefor will require polling is false. USB uses an interrupt, and when a device changes state, it generates a message that causes a USB interrupt. So, you don't poll your USB keyboard/mouse/whatever. Ditto for Firewire.
   
3. USB is too slow for disk drives: That would depend upon what you are using. Would I want to hook up a true hard drive to USB? Of course not! But would I hook a Jaz, Orb, or other removable up? The speeds on these devices are not that large compared to USB, especially USB 2.0 (400MBit/sec).
   

The only thing about USB/Firewire/I2O etc. that worries me is the "You want drivers? Yer runnin' Winders ain'tcha?" mindset most HW venders have. As an embedded systems designer, I am CONSTANTLY telling these morons "No, I am NOT running Windows, I am running a real time OS, and I need the programming specs for that! No, I CANNOT use the BIOS you provide, I am running in protected mode and your BIOS only works in real mode. No, I am NOT running Windows, weren't you listening the first twelve times I told you that?"

However, things are getting better with more HW vendors supporting Linux (therefor releasing source that I can adapt as needed to my needs).

And before you ask, while I am considering using Linux in several projects I am designing, there are other places where it just doesn't make sense, and therefor I have to adapt drivers, not install the RPM. Let's not get into the mindset of "You want drivers? Yer running Linux ain'tcha?" ;^)

PS: Rob, why don't you put a "Spellcheck" button on the post page? It would sure help us all out!