开云体育Just like VM/370’s component Hercules simulates what is in the POP but without timing restrictions. Its very hard to simulate “step ?accurate” or even “similar performance” of an old machine. There are a number of reasons for this. ? I think a major issue is DASD performance. DASD latency seek times and through put are challenging to simulate. Then there are channels, Hercules does not attempt to simulate channel busy. Lastly an intel CPU is very different to an IBM CPU. Things like 360 floating point has to be simulated. ? I think as a first step, run it on a slow host, such as a slow Raspberry PI. Its not as slow as a 360… Second step look the SIMH 360 fork… ? ? I think that Richard Cornwell wanted these to be more realistic, but it does have fixed channels and io devices. ? I guess if you really want step accuracy then you could write your own emulator in VHDL and run it on an FPGA like Laurence Wilkinsons 360/30 project ? ? As this is gate level it should behave pretty much like a real model 30… … but again it needs DASD adding ? Dave G4UGM ? From: [email protected] <[email protected]> On Behalf Of tomarmstrong255@...
Sent: 28 November 2020 22:53 To: [email protected] Subject: Re: [H390-MVS] Hercules, MVS speed. ? Hi Carlos, The 360 Mod 40 was rated at about 125,000 instructions per second or 125KPS. I would expect your 64 bit 3G processor to deliver around 60,000,000 instructions per second or 60MIPS. That is about 480 times faster than a 360 Mod 40. Add in the Hercules I/O buffering and you can see why Hercules emulation on a modern PC processor provides such a huge performance boost over the original 360 hardware. Its not about memory allocation, its all about the 480 times (60,000,000/125,000) improvement in instructions per second. The software, both PL/I F and OS/360 Sort/Merge were designed and written with the memory and performance constraints imposed by the 360 hardware being a major consideration. Providing additional memory, above and beyond their stated memory specifications generally delivers little or no performance improvement as they are not designed to exploit the additional memory provided by MVS. As to your question of slowing down Hercules to deliver similar performance of a 360/40 then that issue would best be addressed by one of the Hercules developers. Regards Tom ? |
