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.

Larry

PS: Don't know of any books on the subject.  We were all too busy.  
:-)

In article <qh3e2tb0w9....@ruckus.brouhaha.com>, Eric Smith