Back when I was in college, the administrative center was run on a 4341, and a 4331 was what supported all the campus¡¯ student computing needs. ?I worked in the lab as an RJE operator.
I think back then it was mostly DOS/VSE with POWER for the campus systems, and then later VM/360 with DOS/VSE running as a VM and eventually MUSIC as another VM for our first interactive computing for the students. ? I¡¯m pretty sure the Admin 4341 was running MVS along with CICS.
I liked MUSIC a lot, but the overall load was WAY more than the machine could handle and RJE job turnaround went up to 24 hours and beyond. ?I burned a lot of midnight oil keeping the printer fed so that the wait times didn¡¯t just keep escalating.
Whether that could be attributed to 43x1 channel performance would be interesting to discover.
Fun times.
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Joe,
Interesting! Contrast that with the top of page 65:-
?
GENERAL OPERATION OF THE CHANNELS?
The channels in the 4341 Processor are microcode and hardware controlled.?
They are integrated channels and, thus, share the use of certain hardware with the instruction processing function,?
such as the arithmetic logic unit, byte shifter, and control storage.
?
The small 43xx were notorious for poor IO performance under heavy load reputedly because of this¡.
?
Dave?
?
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Dave,
Huh? To quote the manual:
"The 4341?Processor generates less?total?interference with instruction execution than intermediate-scale?System/360 and System/370?processors because the?amount?of time required?to transfer?a?byte?of?data?between?processor storage?and?the channel data buffer during?an?I/O operation?is?much?less?(64?bytes are transferred?in?4 microseconds?in the?4341 Processor?versus?4?bytes transferred to or?from?processor storage in?.54 microseconds?in the?Model 148,?for example)."
I dont?see how that can degrade CPU performance for high I/O. In fact, in a high I/O situation, wouldnt?it help??
If 4 bytes are transferred in half a microsecond, that means 64 bytes could be transferred in 32 microseconds, versus 4 microseconds on a 4341...
?
Doug,
On the low end 43xx boxes in effect the channel is implemented using some of the main CPU so device that generate high IO can degrade CPU performance¡
?
?
page 64.
?
The channel throughputs are on 67. Your issue with the 2305 may have been that it needed a selector channel an whilst the machine can do that it reduces the number of block multiplexor channels¡
?
Dave
?
?
2305 was nice because of no seek time. In an Hercules emulated environment, probably doesn't make a difference.
I was on the periphery of a 360/75 MVT -> 4341 MVT under VM transition (I got to do some MVT<->VM integration, much fun! HASP, CP SPOOL, VMCS....). 2305 was our MVT SYSRES. I heard that the channels on the 4341 couldn't keep up with the 2305, even if we dedicated it to the MVT virtual machine,and we had to drop back to a 3330 SYSRES. I'm not sure that last bit is accurate.
The /75 sure was cool, though...
On Wednesday, January 29, 2020, 2:48:12 PM EST, Drew Derbyshire <swhobbit@...> wrote:? On 1/29/20 4:15 AM, adriansutherland67 wrote:
>
> For memory paging - I was wondering if IBM had a paging memory device?
> (clearly not - thanks). Therefore (1) I am going to go ahead with?
> experimenting with a small DASD drive for paging.
I thought there was a bias towards 2305 devices for paging, but too much?
time hanging out with the documents for a certain 4361 and it's VM/SP?
flavor, my brain is probably fogged.
-ahd-
