Debug PM Graph problem

[gs80065xe]

Typed in Chicken Basic program from Antic vol1issue 1. Was crashing when loading the display. Found and fixed some data statement errors. As well as poke errors when I used 1 instead of I. Doesnt crash. But PM is not loading properly. I get that multi colored vertical bar. Checked and rechecked data statements. Cannot find errors. Checked logic where pm area is initialized and players setup. Dont see any typos. How do I track this down? Thanks.

[Caterpiggle]

Sometimes in later on issue's , it may be appear some re-corrections of mistake basic lines from their previous issue like Vol 1 , No. 1 as for example. I do not know which later on issue's.

[Rybags]

Flickering bar might be graphics control or DMA not set properly, or PMBASE not set properly.

 

Look specifically for POKE 559, POKE 53277, POKE 54279 statements and verify.

 

It can also be helpful using Altirra debugger for such problems. Stop with F8 then type .antic and .gtia to get register states.

From there you can determine settings that on real machines can be hard to get since the actual registers are often write-only.

 

PMBASE problems with Basic can sometimes be related to improper memory management. Often it helps with such Basic programs to press Reset in between runs.

Edited April 21, 2018 by Rybags

[+Roydea6]

Dont see any typos. How do I track this down? Thanks.

This is the chicken program that I have from an Antic Disk..

 

CHICKEN.bas

 

IF this is the same program that is being typed in from a listing then comparing them would help track problem.

[+CharlieChaplin]

This is most likely "Chicken" by Stan Ockers. There are several versions available for download at atarimania:

http://www.atarimania.com/list_games_atari_search_67.104.105.99.107.101.110._8_G.html

[gs80065xe]

I downloaded the game from AtariMania. And that worked. So I knew it was a typo somewhere. Thanks for the tips Rybags. I either deleted or missed line 370. It contains the poke statements to init PM graphics. It's working fine now. I'm running on Kubuntu. So I use the Atari800 emulator. I don't suppose it has similar debug capability as Altira? As much as I sometimes despise Visual Studio, it's far easier to debug that Atari Basic.