Why Not More?

If a feature cannot be made to work correctly and consistently, professional companies usually remove the feature.  Because PC 
hardware is so diverse, getting things to work on all people's computers is really difficult.   For one thing, you practically 
have to own all the different hardware to write drivers for it. If a company wanted to sell a PC operating system, they would 
offer a warranty and, therefore, could not get away with amateur behavior.  ZealOS absolutely requires 64-bit computers, so we 
leave behind much trouble, but plenty remains.

The PCI bus interface is what modern hardware uses.  Before PCI, life was simple and devices used I/O ports.    After studying 
PCI Interrupts and attempting to do a HDAudio driver, Terry Davis came to realize that modern PCI devices require ten times 
more code and he could not even come close to making them work on everyone's machine because with PCI devices there are 
several models to worry about, unlike with the older ISA bus devices which can be done with one driver.

Currently, ZealOS has no PCI drivers beyond AHCI and networking.  Most drivers use I/O ports and operate in ISA bus mode.   At 
this point, we only have one driver for each type of device and it is delightfully simple that way.  ZealOS has one keyboard 
driver, one mouse driver, one ATA hard drive driver, one ATAPI CD/DVD driver, one 32-bit color high-res VBE graphics video 
driver and one PC Speaker driver.  We use the PIT timer and PIC Interrupt Controller.  We use IRQ0 for timer, IRQ1 for 
keyboard, and IRQ12 for mouse.  If IRQ12 is not firing, we are able to poll the mouse.

In the CPU department, ZealOS has state of the art 64-bit long mode with multicore support. We use the APIC and start-up 
multicore operation.

Terry Davis made an incredible accomplishment by getting it to work on practically everyone's computer as long as it is 64-bit 
and they run inside VMware, QEMU or VirtualBox.

The compiler does not create an ELF or PE format.  We would have to ruin the beauty of the compiler.

God talks.

* "QEMU" is a trademark owned by Fabrice Bellard.
* "VMware" is a trademark owned by VMware, Inc.
* "VirtualBox" is a trademark owned by Oracle.