September/October 2018 issue of acmqueue The September/October issue of acmqueue is out now

Subscribers and ACM Professional members login here

Virtual Machines

  Download PDF version of this article PDF

Error 526 Ray ID: 47bf6a0e5bc8c5fa • 2018-11-19 02:58:17 UTC

Invalid SSL certificate








What happened?

The origin web server does not have a valid SSL certificate.

What can I do?

If you're a visitor of this website:

Please try again in a few minutes.

If you're the owner of this website:

The SSL certificate presented by the server did not pass validation. This could indicate an expired SSL certificate or a certificate that does not include the requested domain name. Please contact your hosting provider to ensure that an up-to-date and valid SSL certificate issued by a Certificate Authority is configured for this domain name on the origin server. Additional troubleshooting information here.


Originally published in Queue vol. 2, no. 5
see this item in the ACM Digital Library



Jonathan Parri, Daniel Shapiro, Miodrag Bolic, Voicu Groza - Returning Control to the Programmer
Exposing SIMD units within interpreted languages could simplify programs and unleash floods of untapped processor power.

Poul-Henning Kamp, Robert Watson - Building Systems to Be Shared, Securely
The history of computing has been characterized by continuous transformation resulting from the dramatic increases in performance and drops in price described by Moore's law. Computing "power" has migrated from centralized mainframes/servers to distributed systems and the commodity desktop. Despite these changes, system sharing remains an important tool for computing. From the multitasking, file-sharing, and virtual machines of the desktop environment to the large-scale sharing of server-class ISP hardware in collocation centers, safely sharing hardware between mutually untrusting parties requires addressing critical concerns of accidental and malicious damage.

Mendel Rosenblum - The Reincarnation of Virtual Machines
The term "virtual machine" initially described a 1960s operating system concept: a software abstraction with the looks of a computer system's hardware (real machine). Forty years later, the term encompasses a large range of abstractions - for example, Java virtual machines that don't match an existing real machine. Despite the variations, in all definitions the virtual machine is a target for a programmer or compilation system. In other words, software is written to run on the virtual machine.


(newest first)

Michael Rieschl | Thu, 20 Dec 2012 17:01:45 UTC

One of the earliest simulators is the OS 2200 Fault Location by Interpretive Testing (FLIT) product. FLIT has been used by Univac / Sperry / Unisys to simulate an entire OS 2200 environment. The instruction processors are emulated as a register-to-register simulator. The instruction processors, control units, and devices are packet emulators. The tape media are files in FLITs TTF format and the disk media are files in FLITs DTF format.

FLIT has been used to emulate all of the 2200 computer systems prior to development. In our older CMOS systems this was extremely important because waiting for the chips to be designed and waiting for test systems would delay software development. Using FLIT the operating system and associated software could be tested and debugged while the hardware was being developed.

FLIT executes in system mode as described above, but also executes in program mode which is the instruction processor emulator with an emulated 2200 operating system. Program mode is used to load and test 2200 programs.

Additionally FLIT has a post mortem dump mode for program mode and a panic dump mode for system mode. All 2200 panic dumps are processed by loaded into FLIT and are processed by FLIT panic dump functions.


Leave this field empty

Post a Comment:

© 2018 ACM, Inc. All Rights Reserved.