origins of IBM 3740 diskette format

[Brad Parker]

"Michael Holley" wrote:
>Don Hills wrote
>>The original diskette design was for  a microcode load device for an
>>IBM mainframe. I recall there was an IBM Journal of R&D article about
>>it, I'll see if I can find it

I have been meaning to say all along this discussion - I thought they
were designed to local microcode into 370's.  That's the first time I
saw one.  It was stuffed inside a 370 and it had microcode on it.

(I saw the service tech fooling with it and he showed me how it worked.
But then I just *had* to find out what microcode was.  Little did I know
it would be like following Alice down the rabit hole :-)

Can't remember what vintage that machine was. I think it ran DOS/VS and
CICS.  I do remember it had a giant refrigerator box of 3rd party memory
which must have been all of 4mb.  A 370/138 maybe?  That machine ran
24/7 and was generally busy.

heh. I remember I wrote a hack to submit little card jobs from the CICS
terminals.  It would freak out the operators because these jobs would
appear in the print queue from space.  I was quietly told to cease and
decist by my boss :-) 

fortunately I discovered a dec-20 shortly after that.

-brad