360/50 microcode listing

Jon Elson elson at pico-systems.com
Thu May 7 20:48:33 CDT 2015

On 05/07/2015 12:33 PM, Mike Ross wrote:
> 1. IBM would very often lease rather than sell, and take back machines when
> customers upgraded; it was obviously in their interests to control or
> eliminate where possible the market in used machines.
In the early days, that was VERY true, very few machines 
were owned.  In fact, IBM didn't sell a SINGLE machine until 
they were forced to by the US government.  In later years, 
there were a lot of owned machines, many owned by the 
computer brokers, who made a BIG business out of 3rd party 
leasing in the 1970's.
> 2. Gold. A lot of gold in old IBM kit. I knew a scrap dealer in Chelmsford
> UK that did nothing but break old IBM mainframes (only ever big boring grey
> boxes when I was there in mid to late 1990s though!)
A lot less gold in the 360's than in earlier machines.  They 
started using selective plating much earlier than anybody 
else to cut the gold content.  But, there is truth in what 
you say.  But, SMS cards had WAY more gold than the SLT systems.


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