"Vaporlock" technique from Don Lancaster's Enhancing Your Apple II and IIe

2 posts / 0 new
Last post
Offline
Last seen: 6 days 7 hours ago
Joined: May 20 2020 - 00:17
Posts: 5
"Vaporlock" technique from Don Lancaster's Enhancing Your Apple II and IIe

I was reading about Don Lancaster's "Vaporlock" technique for finding the exact timing of the vertical blank during screen refreshes.   Does anyone happen to have the sourcecode available or know where I can find the companion disk that came with Enhancing Your Apple II and IIe I am hoping to avoid typing everything in manually

mmphosis's picture
Offline
Last seen: 9 hours 39 min ago
Joined: Aug 18 2005 - 16:26
Posts: 375
Wow. Thanks for pointing this out

In the mid-80's through word of mouth, I played around with (LDA $C050) what is referred to as the "floating bus", although at the time I didn't know that term. Much much later, I found Bob Bishop's article "Have an Apple Split" from Softalk, October 1982, and others have similar programs that use the floating bus. 

Here is my quick one-liner to see a horizontal video effect:

300:AD 50 C0 EA AD 51 C0 4C 0 3 N 300G

This needs to be run from the MONitor on a real Apple II, or with a cycle accurate emulator like AppleWin, Epple ][, KEGS, ...

 

I've heard others use the term "vaporlock", so regarding Don Lancaster's book, I was able to find a few things ...

The book on Don Lancaster's web site:

https://www.tinaja.com/ebooks/enhance_vII.pdf

page 204 Enhancement 13 PROGRAM 13-1 Listing of VAPORLOCK.SOURCE.

 

A disk with the VAPORLOCK binary program without the source code:

https://archive.org/download/d181s1-mon-rom-vaporlock/d181s1-mon-rom-vaporlock.dsk

 

 

 

 

 

Log in or register to post comments