The short answer from memory:

• At the beginning of a frame the address is set to zero
• The address is incremented over a line for R0 (total chars aka horizontal timing) character access cycles.
• Only R1 (displayed characters) are visible.
• The address is reset after R0 character access cycles.
• Then the scan line counter is incremented
• When the scan line counter reaches R9 (Max Scan Line -1):
  • Scan line counter is reset
  • Address is incremented by R1

Rinse and repeat.

Short answer from memory:

• At the beginning of a frame the address is set to zero
• The address is incremented over a line for R0 (total chars aka horizontal timing) character access cycles.
• Only R1 (displayed characters) are visible.
• The address is reset after R0 character access cycles.
• Then the scan line counter is incremented
• When the scan line counter reaches R9 (Max Scan Line - 1):
  • Scan line counter is reset
  • Address is incremented by R1

Rinse and repeat.

Short answer from memory:

• At the beginning of a frame the address ist set to zero
• The address is incremented over a line for R0 (total chars aka horizontal timing) character access cycles
• Only R1 (displayed characters) are visible
• The address is resettet after R0 character access cycles.
• Scan line counter is incremented
• When the scan line counter reaches R9 (Max Scan Line -1)
  • Scan line counter is reset
  • Address is incremented by R1

Rinse and repeat.

The short answer from memory:

• At the beginning of a frame the address is set to zero
• The address is incremented over a line for R0 (total chars aka horizontal timing) character access cycles.
• Only R1 (displayed characters) are visible.
• The address is reset after R0 character access cycles.
• Then the scan line counter is incremented
• When the scan line counter reaches R9 (Max Scan Line -1):
  • Scan line counter is reset
  • Address is incremented by R1

Rinse and repeat.