winscape 2274

Think of it this way: You can write a compiler that targets the virtualized machine that is presented by the officially blessed compiler.

A byte-code style VM and a VM represented in a HLL are semantically equivalent.

Getting back upthread a few dozen stack frames: Had IBM added the simplest of base-bounds address checking capability, OS Vendors *could* have developed more robust operating systems.

Had my aunt been born with balls, she'd have been my uncle.

There was a vendor of 8-bit micro gear, contemporaneous with the IBM PC that *did* do hardware memory protection, even in absence of the processor "supporting" it.

There were a pair of CPUs - one dedicated to user-land tasks, and one that handled the filesystem and hardware I-O -- there was a wormhole between the two of them, and several sysgen-time configuration options you could put the machine into, to balance protection vs. efficiency.

Because the Z80 does not have restartable instructions, you could not do copy-on-write behavior, so each process had to either share critical system structures (i.e. my bad behavior COULD affect the rest of the machine) or each process had to have its private copy (cutting the number of processes that could run.)

We could run the development machine (which had very few users - just me and another programmer ) in the least-efficient but safest configuration. When we were reasonably sure the code was stable, we could copy the binary over to the production machine, that had to run in the less secure mode to handle the number of data-entry clerks using it.

The machines we had, were the IBC Midi-Cadet running OASIS. The hardware reference platform was published, and there were two or three other manufacturers who supported the OS (Altos being the largest).

I kept one of the IBCs for years and years, but in the end, the old Quantum 540 became too unreliable to even boot, so with tears in my eyes, it went to the skip.

As far as we could tell, the OS was written by ONE guy: Timothy S. Williams, and was a beautiful joy to use.

An 8086 version was done later, and at some point was renamed Theos.

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order.