I built myself a console//console.jpg
and I realized there is something wrong with the graphics - most of the sprites are displayed incorrectly//bugs.jpg
I blamed the PPU of course, but after replacing with different chip - problem persisted. CPU RAM & PPU RAM passed tests, all connectios are ok. After replacing the CPU, problem was solved, so "Seniton 6527UP-8" CPU is the culprit.//cpu.jpg
I ran the OAM stress test which display all the sprites and instead of correct diagonal pattern (left), I got some staircase one (right)//oam.jpg
While most of the games work correctly (except the buggy sprites), there are a few other quirks:
* statusbar in many of the games, using MMC3 irq counter is shaking (which suggests there is something wrong with the M2-PPU A12 relationship), but this CPU's M2 seems to have standard 9/15 duty cycle (1.77344 MHz clock)
![Image]()
//m2.PNG
* while only sprites in most games are affected, some games, like Jetsons have also some other graphics corrupted://jetsons.jpg
* Most of the Codemasters' games failt to work at all:
-Fantastic Adventures Dizzy for example - hangs on the "Dizzy" title screen, you cant do anything, but the music is still playing
-Micro Machines - allows you to start the racing level but then it hangs immediately.
and I realized there is something wrong with the graphics - most of the sprites are displayed incorrectly
I blamed the PPU of course, but after replacing with different chip - problem persisted. CPU RAM & PPU RAM passed tests, all connectios are ok. After replacing the CPU, problem was solved, so "Seniton 6527UP-8" CPU is the culprit.
I ran the OAM stress test which display all the sprites and instead of correct diagonal pattern (left), I got some staircase one (right)
While most of the games work correctly (except the buggy sprites), there are a few other quirks:
* statusbar in many of the games, using MMC3 irq counter is shaking (which suggests there is something wrong with the M2-PPU A12 relationship), but this CPU's M2 seems to have standard 9/15 duty cycle (1.77344 MHz clock)
//m2.PNG
* while only sprites in most games are affected, some games, like Jetsons have also some other graphics corrupted:
* Most of the Codemasters' games failt to work at all:
-Fantastic Adventures Dizzy for example - hangs on the "Dizzy" title screen, you cant do anything, but the music is still playing
-Micro Machines - allows you to start the racing level but then it hangs immediately.
Statistics: Posted by krzysiobal — Fri May 17, 2024 12:24 am — Replies 1 — Views 182