ZX Spectrum Emulator

This site is sponsored by:
Grok Developments
Grok Developments Ltd


The following people have contributed towards the development of vbSpec:

Chris Cowley - Author and maintainer of vbSpec. Head of Subtle Bug Development ("look, if I didn't put subtle bugs in it, what incentive would there be for anyone to upgrade?")

vbSpec Version 1.6 Contributors

Mark Woodmass has provided some performance-related enhancements and has also supplied an improved routine for decoding port addresses (this basically means that vbSpec v1.60 is more accurate and will work with more obscure and unusual demos and games!). He also assisted me in tracking down a problem with loading certain TZX files and generally supplies help and moral support by putting up with my long, rambling e-mails!

Gonchuki has sent me many optimizations to vbSpec's core Z80 routines and display routines. You have him to thank for a considerable portion of v1.60's improved performance!

Ignacio Burgueno helped me with a TZX compatibility problem. Ignacio is the author of Gleck, another fine Spectrum emulator for Windows.

Andrew Owen has kindly given permission for his SE Basic ROM image to be distributed with vbSpec. More information about SE Basic is available at The World of Spectrum Sinclair BASIC pages.

As always, the residents of the comp.sys.sinclair newsgroup and various other emulator authors have also been a great help.

vbSpec Version 1.50 Contributors

Mark Woodmass Mark (or Woody, as he is more commonly known to the denizens of comp.sys.sinclair) developed and submitted the code for v1.50's TZX support, as well as tracking down and fixing a couple of well-hidden bugs in vbSpec's Z80 core. For those of you not in the know, Woody is also co-author of SPIN, an extremely accurate and complete Spectrum Emulator for Windows.

vbSpec Version 1.30 and 1.40 Contributors

Andrew Owen Andrew provided the specification of the Timex TC2048 extended display modes and timings, based on experimentation with his real TC2048. This information is now available for other emulator authors in the comp.sys.sinclair FAQ. He also beta-tested the TC2048 support and provided various pieces of test code that allowed me to get the TC2048 hi-res/hi-colour display modes working properly. Andrew has also produced this slideshow of hi-colour pictures to demonstrate the features of the TC2048.

Bob Woodring Supplied numerous improvements and performance enhancements to the display code, based around using pre-calculated lookup tables for various display-related calculations. For the curious, his contributions are labelled 'RGW' in the source code.

Russell Marks Provided suggestions for improving the accuracy of the AY sound in vbSpec by modifying the volume table to more acurrately represent the measured voltages from a genuine 128K Spectrum.

Many of the denizens of the comp.sys.sinclair newsgroup, including Philip Kendall and Mark Woodmass, have also provided me with suggestions and invaluable assistance about the finer points of the Spectrum hardware.

I would also like to thank the numerous other people who have contributed ideas and source code for vbSpec. I had no idea that the project would become as popular as it has, and I wasn't expecting the volume of contributions that I've received! I may need to set up a CVS tree for vbSpec in the near future as I currently have conflicting code for a large number of new features. Working through these patches and additing them to my primary copy of the source will take some time. However here are some brief details of what I have yet to add:-

vbSpec Version 1.20 Contributors

James Bagg James is responsible for adding the sound support to vbSpec 1.20. Not only did he do the majority of the groundwork and research required to emulate the 48K Spectrum's beeper, he also provided code for emulating the AY-3-8912 three channel sound of the 128K Spectrum models. It was quite an experience for me to hear vbSpec producing full 3 channel sound and effects for the first time -- he's done an excellent job I think!

vbSpec Version 1.10 Contributors

Miguel Santos Miguel is the person responsible for the substantial performance increase in v1.10. His tips included replacing floating point division with integer division throughout the Z80 emulation, replacing Iif() functions with block If's, and replacing various occurences of integer and byte variables with longs. He also made various helpful suggestions about improving the efficiency of the native VB display routines. The end result is a version of vbSpec that runs around 2-3 times faster than the previous release!

Sebastien Bauer Supplied patches to enhance the keyboard routines with support for the PC backspace key and numeric keypad.

David Bridson Sent some suggestions for improving the display speed in vbSpec 1.00

Copyright ©2002 Grok Developments Ltd