Though multitasking and VMs on the AGC were a feat, that's not what amazes me. The IBM 360 demonstrated that both were possible at the time, and the AGC impressively did it on less hardware. What does amaze me is how long it took such things to come to the personal computer, and arguably how much DOS/early Windows held things back. Unix, with its multitasking, ran on PCs and Macs in the 80s, so we only waited 20 years after the 360 (and 15 after the AGC) for multitasking. But usable VMs didn't come (or at least weren't commonplace) until, what, mid-90s? 30 years after the 360, and 25 after the minimal AGC? What the heck took so long?
Few personal computers had protected memory until the late 1980s. Unix didn't run on PC or Mac until protected memory hardware was available.
Emulation was always popular, and it is a type of virtualization. Few people wanted to emulate the same platform they already had. Pure software emulators were pretty slow in the 1980's, unless the target platform had the same cpu as the host.
My family had an Amiga and we had both a bridge board and an A-Max. The bridge board was a full PC on an expansion card, so its not really a VM. The A-Max was more like a VM. Its hardware contained the Apple ROMs and a floppy disk interface because the Amiga floppy drive could not read Mac disks. The software used the ROMs and Apple floppy drive to emulate a Mac.
Now that I think about it, I think the real reason was ram and to a lesser degree hard drive space. My first encounter with virtualization in Linux happened when most people were running between 8 and 64mb of ram. 64mb of ram was very expensive. That's a pretty big constraint.
Comments
Though multitasking and VMs on the AGC were a feat, that's not what amazes me. The IBM 360 demonstrated that both were possible at the time, and the AGC impressively did it on less hardware. What does amaze me is how long it took such things to come to the personal computer, and arguably how much DOS/early Windows held things back. Unix, with its multitasking, ran on PCs and Macs in the 80s, so we only waited 20 years after the 360 (and 15 after the AGC) for multitasking. But usable VMs didn't come (or at least weren't commonplace) until, what, mid-90s? 30 years after the 360, and 25 after the minimal AGC? What the heck took so long?
Few personal computers had protected memory until the late 1980s. Unix didn't run on PC or Mac until protected memory hardware was available.
Emulation was always popular, and it is a type of virtualization. Few people wanted to emulate the same platform they already had. Pure software emulators were pretty slow in the 1980's, unless the target platform had the same cpu as the host.
My family had an Amiga and we had both a bridge board and an A-Max. The bridge board was a full PC on an expansion card, so its not really a VM. The A-Max was more like a VM. Its hardware contained the Apple ROMs and a floppy disk interface because the Amiga floppy drive could not read Mac disks. The software used the ROMs and Apple floppy drive to emulate a Mac.
Now that I think about it, I think the real reason was ram and to a lesser degree hard drive space. My first encounter with virtualization in Linux happened when most people were running between 8 and 64mb of ram. 64mb of ram was very expensive. That's a pretty big constraint.