[Info-vax] Hobbyist licences for VAX

[Bob Eager]

On Fri, 15 Apr 2022 18:16:58 -0700, gah4 wrote:

> As long as they don't use track overflow, that is, actually write tracks
> using it,
> you don't notice the difference.  As well as I know, the only problem is
> in the paging file for MVS, and only on devices that support track
> overflow.

See below.

> I had thought it was only 2314 and 3330, but the above suggests 3340. As
> well as I know (it was years ago when I thought about this) it is not on
> the 3350, 3380, or 3390.

This is an OEM of the 3330 mechanism, using 3336 packs. It's the ICL 
EDS100 and EDS200.

The operating system uses the track overflow feature for IPL. The whole 
boot program sits in linked records/tracks starting at 0. The IPL thus 
loads the entire boot program in one go. I think it's written in separate 
records, but I'll implement that anyway.

The boot program is large; it's actually a chopped down supervisor. It 
can be IPLd from tape (the tape IPL is more complicated!) and can then be 
used to format the disk and copy a system down onto it. It also contains 
an extensive GROPE[1] feature, some diagnostics, disk and tape labelling 
and a load of other stuff!

[1] For those who don't know...General Reconnaissance Of Peripheral 
Equipment!



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