What is the system in the system numbers?

[Abmvk]

I understand some of the letters. S for System. PS for Personal System. AS for Application System. I get that. But how did Big Blue come with the numbers? Why is there a 700 (and 701, 702, and so on), but as far as I could find no 600. Although there was a Thinkpad 600.

Why a S/36 and a S/38, no S/37, and than the next follow up is the AS/400? I can find the S/360, obviously, and then the S/370 why not. But then the S/390 and no S/380? And neither a S/350 although there is a eServer xSeries 350.

It seems obvious that there is some kind of system in those system-numbers, but what is it?

 

[RetroAND]

When there's marketing involved, there's no need to be logical. You only have to see the Windows sequence...

 

[Hak Foo]

The '360' name was because it was supposed to unify IBM's previous 'engineering' and 'business' computer product lines, so 360-degrees was cutesy. The 370 range were '70s updates, and the 390 was 1990s updates. Perhaps the mainframe division was a bit under the radar in the 1980s and didn't need a marketing-oriented naming cycle.

 

[jlang]

A place I worked at in the 80's picked model numbers based in the estimated price.
model 5000 $5000
model 2500 $2500
model 150 $150
See the pattern?

I do have to admit to seeing model numbers picked with a dart board on occasion.

 

[Al Kossow]

IBM products have three or four digit product numbers followed by a model up through at least the 90s
the 1980 32 bit CPU products were 4300 and 30xx
Hardware documentation on bitsavers is mostly organized numerically http://bitsavers.org/pdf/ibm

"System" products like S/3 32 34 36 and 38 AS/400 came out of IBM Rochester MN they had four digit product numbers for individual components
They are all even numbers

http://bitsavers.org/pdf/ibm/productDescriptions/IBM_Sales_Manual_Machines_Section_Jul79.pdf
for descriptions of products up to that point.

 

[RetroAND]

IBM products have three or four digit product numbers followed by a model up through at least the 90s
the 1980 32 bit CPU products were 4300 and 30xx
Hardware documentation on bitsavers is mostly organized numerically http://bitsavers.org/pdf/ibm

"System" products like S/3 32 34 36 and 38 AS/400 came out of IBM Rochester MN they had four digit product numbers for individual components
They are all even numbers

http://bitsavers.org/pdf/ibm/productDescriptions/IBM_Sales_Manual_Machines_Section_Jul79.pdf
for descriptions of products up to that point.

System/23 is the odd exception to the rule, I guess.

 

[tofro]

The PC range shows a bit of logic in the 4-digit numbers:

5150 - the original PC
5160 - the XT with hard disk
5161 - the slot expansion box
5162 - the XT with 286 CPU (XT/AT)
5170 - the original IBM AT

5531 - industrial ruggedized version of the XT
7531 - ruggedized AT in 19"

..... and many more

So, Personal computers used "51" as the first two digits, the latter two digits gave the models (and seem to have been used more or less chronologically). Ruggedized machines used "31" as the last two digits.

 

[Al Kossow]

System/23 is the odd exception to the rule, I guess.

sigh.. I was only talking about S/3x since someone asked why there was no S/37