Phoenix bug hunting
Date: Friday, August 29 2014 @ 11:17:31 UTC
Topic: Amiga FPGA accelerator
Last few days it was lot of fun and hard work to find bug who stopped us from booting into Workbench and complete Apollo-team worked on this. Those who visited our irc channel could see huge motivation from all members to track it down. As you can see on the pictures shown in this article Kickstart 1.3 had some problems with displaying fonts so after investigation we narrowed our potential bugs to Blitter area. Next logical step was to compare information's from original CPU to the Phoenix results. I must say that it was so hard to capture all needed information's using SignalTapII because somehow I was receiving a lot of junk data and serious filtration was needed to capture only information's we can use. What we wanted is to compare those registers: BLTCON0, BLTCON1, BLTAFWM, BLTALWM.
| CPU |
Data |
Address register |
Register name |
| MC68000 |
071A
0002
FFFF
FFFF |
DFF040
DFF042
DFF044
DFF046 |
BLTCON0
BLTCON1
BLTAFWM
BLTALWM |
| Phoenix |
071A
0002
0000
0000 |
DFF040
DFF042
DFF044
DFF046 |
BLTCON0
BLTCON1
BLTAFWM
BLTALWM |
This result shows us where problem was and it means that sometimes Blitter Registers DFF044 and DFF046 are not correctly set with "FFFF" but with "0000". After isolating problem it was just matter of time when we will find it in code and fix it. And yes today we made it happen. You may ask yourself why is he writing about something that is already fixed. This article belongs in the history, today was crucial day for this project, today real magic happened and from this day on you will start to believe again!
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