Rescue update: DEC RC-25s + / was Re: DEC cartridge ID

[tony duell]

> The RC25 was one of the last cartridge drives (before fixed drives came back in small sizes and exploding 
> capacity), somewhat interesting because of its compact size, and very odd and hard to use because the 
> designers threw in a fixed platter.  Perhaps they thought that it was a good idea because it gave you double the 
> capacity at modest extra cost, but in practice it made for a major pain in the software and operationally.

Many other compainess pulled a similar trick...

The CDC 'Phoenix' (is that a 9648 or something) had a removeable pack containing one  platter and 
3 fixed platters. Capacity was 16MBytes per surface (or so), so the removeable pack stored 16Mbytes)
(one data surface, one servo surface), the fixed part was 80 MBytes (5 data, 1 servo surface).

Plessey made an RK05-a-like (same interface, linked to their version of the RK11-D, took same 
cartridges, same format, etc) with a fixed platter as well as the cartridge. Of course the HP7900 was
like that too.

I never really liked the idea. The main problem was you lost access to the fixed disk(s) while changing the
removeable one. 

-tony