Editing microsoft/scorpio engine (section)

== Memory controller ==
The memory architecture of the Scorpio Engine is very different from the previous generational chip. The entire memory subsystem was redesigned to address the major deficiencies in prior chips. In previous chip, Microsoft chose to go with 8 GiB of quad-channel [[DDR3]] on-board operating at 2133 MT/s for a total system memory [[bandwidth]] of 63.58 GiB/s. That was fairly low by any standard; at the time the PS4 SoC had a peak memory bandwidth of 163.9 GiB/s. In an attempt to mitigate the lack of bandwidth, the chip incorporated 32 MiB of [[eSRAM]] with a bus of 1,024-bit in each direction for a total bandwidth of 190 GiB/s. While this reduced the cost of memory considerably, it increased the cost in terms of die area (which would be roughly 1.6B transistors). Additionally, this architecture also made the programming model more complicated to work with.

The Scorpio Engine made a 180-degree turn vs previous chip architecture-wise. The entire memory subsystem has been re-designed with GDDR5 and high bandwidth in mind. The previous 32 MiB of [[eSRAM]] has been eliminated. Instead, Scorpio has a maximum bandwidth of 304 GiB/s through a 384-bit wide [[DRAM]] interface with an effective transfer of 6800 MT/s. The bandwidth increase has effectively reached the level of a discrete graphics card and almost 1.5x the bandwidth of the PS4 Pro (which is 203 GiB/s).

Console systems will come with 12 x32 [[GDDR]] chips for a total of 12 [[GiB]] while the development system will come with x16 chips for a total capacity of 24 GiB. Scorpio has 12 [[DRAM controllers]] for each of the 12 channels. It's worth noting that in order to maintain backwards compatibility with the Xbox One software, the [[CPU]] and [[GPU]] accesses the memory separately. The exact details of how the CPU accesses the memory has not been detailed. As with the previous generation, a bidirectional bus sits between the [[memory controllers]] and the CPUs and GPU. The bus maintains [[coherency]] between the CPU cores and the GPU. For the GPU, each of the 12 [[memory channel|channels]] is a 256-bit directional bus for a total bus width of 3,072-bit. The 12 channels allow the system to lower the granularity of memory accesses while the wide bus allows the system to take full advantage of the available bandwidth.

{{memory controller
|type=GDDR5-6800
|ecc=No
|max mem=24 GiB
|controllers=12
|channels=12
|width=384 bit
|max bandwidth=304 GiB/s
|bandwidth schan=25.33 GiB/s
}}
base frequency	2,300 MHz (2.3 GHz, 2,300,000 kHz) +
core count	8 +
core name	Enhanced Jaguar +
designer	AMD + and Microsoft +
die area	359 mm² (0.556 in², 3.59 cm², 359,000,000 µm²) +
first announced	June 11, 2017 +
first launched	November 7, 2017 +
full page name	microsoft/scorpio engine +
has ecc memory support	false +
instance of	microprocessor +
is multi-chip package	false +
isa	x86-64 +
isa family	x86 +
l1$ size	512 KiB (524,288 B, 0.5 MiB) +
l1d$ description	8-way set associative +
l1d$ size	256 KiB (262,144 B, 0.25 MiB) +
l1i$ description	2-way set associative +
l1i$ size	256 KiB (262,144 B, 0.25 MiB) +
l2$ description	16-way set associative +
l2$ size	4 MiB (4,096 KiB, 4,194,304 B, 0.00391 GiB) +
ldate	November 7, 2017 +
main image	+
manufacturer	TSMC +
market segment	Console +
max cpu count	1 +
max memory	24,576 MiB (25,165,824 KiB, 25,769,803,776 B, 24 GiB, 0.0234 TiB) +
max memory bandwidth	304 GiB/s (311,296 MiB/s, 326.418 GB/s, 326,417.514 MB/s, 0.297 TiB/s, 0.326 TB/s) +
max memory channels	12 +
microarchitecture	Enhanced Jaguar + and Polaris +
model number	Scorpio Engine +
name	Scorpio Engine +
package	BGA-2409 +
package contacts	2,409 +
package length	50 mm (5 cm, 1.969 in) +
package pitch	0.8 mm (0.0315 in) +
package type	FC-OBGA +
package width	50 mm (5 cm, 1.969 in) +
process	16 nm (0.016 μm, 1.6e-5 mm) +
smp max ways	1 +
supported memory type	GDDR5-6800 +
technology	CMOS +
thread count	8 +
transistor count	7,000,000,000 +
used by	Xbox One X +
word size	64 bit (8 octets, 16 nibbles) +