Uploads from NostalgiaPC

Currently Playing: I removed the 64KB barrier from the operating system

This video is about a memory release for os8088, the graphical operating system for the IBM XT you can download at os8088.com. See the release information at https://github.com/jggonz/os8088/releases/tag/v1.0.20260729 The task stacks, the disk buffers and two of the coldest modules move out of the kernel's 64KB segment, taking the headroom left for future features from 1,089 bytes to 28,129. What changed Room to grow -- 1,089 bytes of headroom becomes 28,129 (#24) The kernel was not short of memory, it was short of segment: everything it touched through DS had to fit in one 64KB window, and 59% of that budget was uninitialised scratch. The task stacks alone -- eleven of them at 1,536 bytes -- were 41% of the window. Three moves fixed it. The stacks and the floppy buffers went to their own segment at linear 0x08000, in low memory that sits free on every machine once the boot sector hands off, which is 20KB back. The package pool slid up from 0xA000 to 0xB000 into the 4KB that task 0's stack used to occupy. And two cold modules, the Control Panel and the Task Manager, now assemble into a far segment that is copied out of the kernel image at boot and lands on top of .bss -- 2,922 bytes of code that costs the window nothing. Nothing left conventional memory and nothing on screen changed, so a 256KB machine behaves exactly as before. The RAM figure means something different now The site said 39,871 bytes last release and says 16,927 this one. No code was deleted -- the number counts what the kernel keeps inside its own segment, and the stacks and disk buffers that made up most of it still exist, just at another address. The ceiling moved too, from 0xA000 to 0xB000, because the package pool moved with it. The Task Manager's RAM total and its System row both add back what now lives outside the segment, so its rows still sum to the total. Packages load at a new address. The pool moved from offsets 0xA000-0xEFFF to 0xB000-0xFDFF and is 19,968 bytes rather than 20,480. A .o88 built before this release carries the old link base in its header and will not load -- reassemble it against the current SDK. The three packages on the software floppy here are already rebuilt.