CDC 6600 - Why so awesome?

Rich Alderson RichA at
Tue Jun 21 17:43:24 CDT 2016

From: Swift Griggs
Sent: Tuesday, June 21, 2016 2:06 PM

> - It used odd sized (by todays standards) register, instruction, and bus 
>   sizes. 60 bit machine with 15/30 bit instructions. But, didn't it cause 
>   a bunch of alignment issues for you ?

???  Alignment issues?  Care to define this?  Are you thinking of bytes?

The word is the addressable unit of storage.  Compilers (well, the FORTRAN
compiler, to start) and the assembler inserted 15-bit no-ops as necessary
to pad the 60-bit words of a CP program.  PP programs fit five 12-bit
instructions per word.

Character codes are 6- or mixed 6/12-bit, packed into the 60-bit word.

Where would you see alignment issues?


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at

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