booting firmware in winape

[Fran123]

Hello

I have observed that Winape during CPC6128 startup changes the value of register R52 from 0x1F to 0x00 (R52 is the register that goes from 0 to 51 to create interrupts). Additionally, this change occurs during an LDIR instruction.

If you try to see it:
at T=15478 -> R52=1F
and in the next state
T=15484 -> R52=00

Why the change? R52 is supposed to reach 0x33 at most

[I attach two images in which you can see what I say. Ignore the labels in winape, the code that appears belongs to the OS6128 ROM]

Thank you.

[abalore]

R52 is reset after a vsync, is there a chance a vsync is happening there?

[McArti0]

https://www.cpcwiki.eu/index.php/File:ACCC1.8-EN.pdf

Page 274 §26.1-3

Maybe this will solve the mystery.