Misuse of word "microcode" 99
Misuse of word "microcode" 101
Peter Flbutt I note also in the low-end 360s, not only was 360 instruction set implemented using the instruction set (microcode) of the native...
John Savard sense
the low-end 370 machines tended to have vertical microcode .... instruction set that looked very much like regular instructions. many of these implementations ran at approximately 10:1 ration ... i.e. avg ten microcode instructions executed for every 370 instruction. misc. past m'code postings:
Misuse of word "microcode" 100
the 370 115-125 were another interesting microcode machines. the basic machine had a shared memory bus with ports for up to nine processors. a...
one of the things that was for ECPS project was to identify the highest executed kernel paths and translate them into microcode. for the ecps kernel paths, there was about a 1:1 translation from 370 to microcode ... achieving a 10:1 performance improvement. the project was started for 370 138-148 new machines when they determined that they had approx. 6kbytes of unused microcode instruction space and was looking for new stuff that could be done to use up that space.
misc. past ecps postings
the high-end 370s used horizontal microcode which was a much more difficult programming undertaking. introduced at some point by the amdahl 370 clones was something called "macrocode" .... it was a microcode mode for the amdahl 370 clones that used a subset of the 370 instruction set (and didn't support self-modifying instructions, a long-term performance issue in standard 370 architecture). 3033 cross memory services, 370-xa, and follow-ons were starting to introduce much more complex processor operational characteristics ... most of them in privilege or supervisor mode and some not very performance sensitive. it was significantly easier for amdahl to implement many of these features using a subset of 370 instruction set than the native machine horizontal microcode.
amdahl also introduced a hypervisor mode for their processors that was implemented mostly in "macrocode" .... basically a subset of virtual machine operating system. IBM eventually responded to the amdahl hypervisor support with PR-SM which has since evolved into LPARs (logical parbreastions).
random past posts mentioning pr-sm, lpars: Machine, the IBM sort) Machine, the IBM sort) Machine, the IBM sort) ultimate CISC? designs) ancient history (slightly off topic) in use? (Do we still share?) Microkernels communicate missing a great opportunity... missing a great opportunity... instructions (was Re: Did Intel Bite Off More Than It Can Chew?) about z900 from IBM Programmer-Administrator market demand? UNIX-Linux systems? Problems books-guidenance mainframes mainframes for small clusters for small clusters than modern crap ! addressing use... OS390? z-os? I'm a Vendor S calculation architecture and compiler support virtualization in general