Newsgroup: it.comp.retrocomputing
Titolo: Architettura sistemi IBM S/3x

Mentre spulciavo vecchi post in alt.folklore.computers ho trovato una breve
descrizione che mi pare abbastanza interessante (se qualcuno ne ha bisogno,
con un po' di pazienza si potrebbe anche tradurre...). Di seguito ne ho
messa un'altra pi� software che hardware e relativa al System/36, che di
fatto � un System/34 migliorato e potenziato, ma sempre della stessa pasta.
Ciao,
G.
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The first systems I worked on were the '32 and '34.  That was a long
(very long) time ago.
The circuit technology for both machines was an IBM bipolar technology
that had 100 to 120 circuits per chip.  Ok for it's time.  It's
internal code name was Dutchess.
The processor on the '32 was a 16 bit register based machine that is
philosophically similar to RISC.  All logical and arithmetic
operations are performed with register to register operations (16
16bit registers). Branches used the side effects of the register to
register operations or tested registers directly.  Memory operations
only load data to registers or store data from registers. Memory was
logically divided into an instruction space and a data space (aka
control store and main store).  On the '32 the two spaces were
physically implemented as one.  There was no cacheint, branch
prediction, etc.  The internal name of the processor was the CSP
(Control Store Processor).
The kernal and I/O processing of the '32 was implemented in the native
instruction set of the CSP.  The upper levels of the operating system
and application code were in the System/3 instruction set.  The '32's
RISCish processor implemented an emulator of the S/3 instruction set
to run the code.  
The S/3 instruction set is almost diametrically opposed to the '32
instruction set.  It is very memory to memory oriented with very few
registers.  All logical and arithmetic operations in the S/3
instruction set are performed on memory to memory operations.  The few
(2) registers were used to index addresses to memory.
All of this emulation was ok for one user, but pretty slow is you
wanted to run multiple users.  So the '34 took the emulator out of
software and put it into hardware (Dutchess technology).  
This processor was called the MSP (Main Store Processor).  To be
clear, the '34 had two processors in its "CPU".  The original CSP from
it's System/32 heritage and the MSP.  Neither processor supported
virtual memory.
The I/O was also interesting on the '34 since it introduced the IOP
(I/O Processor to the mix).  But that's another story.
http://groups.google.com/group/alt.folklore.computers/msg/4989d05ea0caab09
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It's been a while but here goes a very high level explanation
CSP - Control Storage Processor
This processor with it's dedicated memory was responsible to Boot the
system (IML), Talk to the many controllers like disk, communications etc
and to monitor health of the system. It talked to the HW and ran what we
called microcode.
MSP - Main Storage Processor
This processor with it's dedicated memory was where the OS and User
Programs were loaded and executed. So to read a file and do something
with it went kinda like...
Program in MSP needs a record from disk
That request would be passed to the OS
The OS would add whatever info it could about where on disk etc the data
was and pass it the CSP and continue to do other work until the CSP
signaled the MSP it had the data.
Mean while the CSP added whatever it need to and passed the request to
the disk controller.
The disk controller would issue the correct read cmds etc and when the
data had been read would either pass that data backup the chain or it
could setup a DMA (direct memory access) and the data would go directly
into main storage from disk. and signal the MSP where the data was for
the app. 
http://groups.google.com/group/comp.sys.ibm.sys3x.misc/msg/badd3684ee0570b7

 fatto � un System/34 migliorato e potenziato, ma sempre della stessa pasta.
ah, come e' la situazione attuale su alt.folklore.computers ? un annetto 
fa l' ho dovuto abbandonare a causa di una combinazione di pesante 
spamming e uno o due "attention whores" che floddavano il NG causando 
discussioni molto lunghe....
Ringraziandoti in anticipo, i miei
Saluti,
dott. Piergiorgio.

 causando discussioni molto lunghe....
interessante questa definizione.. non la conoscevo. Anni fa ho
incrociato anche io un "attention whore", su un ng locale di una citt�,
un vecchio frustrato e lasciato dalla convivente, che non lavorava e
passava le giornate a gettare discredito sulla gente del ng che non gli
dava corda, finendo con l'attrarre a s� la gente pi� codarda. Si
firmava con uno pseudonimo ma � stato scoperto e denunciato da uno che
ha portato all'esasperazione nel corso di mesi di (letteralmente)
persecuzione in stile stalking. Chiss� come � finita.
Ale