We did this in our Sinclair Spectrum games to blit the backbuffer to the display memory. Interrupts were not a problem because if they occured during the PUSH (

We did this in our Sinclair Spectrum games to blit the backbuffer to the display memory. Interrupts were not a problem because if they occured during the PUSH (display memory), the corruption would be overwritten immediately when the blit continued, and if they occured during the POP, the backbuffer was going to be overwritten in its entirety the next frame. However, we had to leave some space at the edge of backbuffer memory, because if there's an interrupt right at the beginning of the blit, the interrupt handler's stack frame could overflow outside of the backbuffer and corrupt other memory. That one was fun to find. [Edit]: I seem to have missed the second footnote where he already describes this issue.