Dennis Musselwhite's Home Page

Welcome to my home page!

I work (primarily) on the Control Program (CP) in the Connectivity area. This includes ISFC (Inter System Facility for Communication), and more recently has expanded to include Virtual Channel-to-Channel (VCTC) and Virtual Network Interface Card (NIC) support. Virtual NIC support is better known as VMLAN or Guest LAN support.

[Musselwhite at the white board]

The following links are intended to supplement (not replace) the official IBM publications.

Professional Background

  • I earned a B.S. in Computer Science at North Carolina State University (NCSU-Raleigh).

  • I worked as an application programmer for Burroughs Wellcome Co at Research Triangle Park, North Carolina. My job involved design and implementation of application programs to support the analysis of their research data. Most of these applications were written in PL/I (with an occasional FORTRAN program).

  • I joined IBM to work in CP Development at Endicott, New York. Most of my projects have involved I/O device support or simulation. For example, I worked with two other developers to write support for the printers that were added in VM/SP Release 3 (this was back before "Version" became significant). Most of my programming is done in Assembler Language.

  • For VM/ESA Version 2, Release 1.0 I was responsible for redesigning the Virtual CTCA simulation in CP to more closely emulate the hardware and to improve performance.

  • For z/VM Version 4, Release 2.0 I worked with a small development team to create a fully simulated network adapter providing connectivity between Linux guests on the same CP host. This is generally known as Guest LAN support.

  • For z/VM Version 5, my primary focus was improving and enhancing our virtual networking capabilities. I was part of the team that designed and implemented VSWITCH, IEEE VLAN, and OSA Layer 2 support.

  • For z/VM Version 6, my primary focus has been improving our ISFC (Inter-System Communication Facility) capability. I was part of the team that designed and implemented ISFC link protocol changes to improve the throughput of the ISFC link and to spread the ISFC traffic across multiple physical CTCA links.

You can reach me at: