1. LIOCS

LIOCS wasn't an operating system. The System Ten didn't really need one, as such, but the actual OS was called DMF (Disk Management Facility). There were two versions, DMF-I, and DMF-II, which was far superior. LIOCS was equivalent to the access method system on the mainframe. A series of subroutines that handled file management.

2. Partitions

A partition had to have at least 1K. There were index registers mapped to memory locations (11, 21, 31) in that area, and there was a failure address, I think in 41. You also needed a place for the boot instruction. SIPOS, which was the retail software, (also called MDTS) ran mostly in Common, but stored pointers, indices, etc. in low partition memory.

3. Divide

Divide worked similarly to Multiply. If I recall correctly, the quotient was left in the LA part of the result, and the remainder in the LB part, but I'd have to look at my booklet to tell for sure. Unfortunately, it's packed up right now.

4. Other Instructions

There was also an "Exchange" instruction, a "Move address" instruction on the model 21 that preserved the zone bits, and an "Add address" instruction on the model 22 that handled overflow between memory pages. While common could go up to 60K on a model 21, you could go to 80K in both common and partitions on a 22. Anyway, that about exhausted the op-code range. 16 instructions was the limit.

5. Partition Types

5) There were several other types of partitions: A clock, that kept time by providing the number of seconds between reads, an Async adapter called an ACA, a Bisync adapter, called an SCA, and in later years, an ATA card to talk to standard Async terminals.

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