MB87P2020 Datasheet, PDF (201/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

Graphic Processing Unit
5.2.1 Average Bandwidth
This estimation is done on the basis of the visible¹ layer area, i.e. the area of active layers within the geo-
metrical borders of the physical display, since all pixels displayed had to be fetched.
The mean number of words (which is equal to the number of core clock cycles) transferred from memory
is calculated as follows:
∑ ^W GPU ⁼
visible
layers


Area_l
⋅
p^----p^---w^-1---_l^-_o^--_g^--_,^--_l^
(24)
The number of pixels per VideoRAM word was already given in table 5-1. For correct GDC function con-
dition (25) must hold:
T _frame ≥ T _CoreClock ⋅ (W _GPU + W _{other units})
(25)
5.2.2 Peak Bandwidth
As already mentioned in section 5.1.2, GPU processes data in portions of a line segment. This implies that
the segment with the maximum number of words fetched has to be found (it should be noted that this is not
necessarily the segment with the maximum number of pixels). The algorithm used to find this segment is
1. The area counts also as visible if a layer is (partially) covered by another layer.
Bandwidth Considerations
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