The Exynos 7 Octa (7870) processor was a mid-range chip from Samsung for mobile phones and tablets. It was the chip release just before the Exynos 7 Octa (7420) was released. You can find those specs here. You will note from the specs listed below that the Exynos 7 Octa (7870) does not have a secondary processor. We will explain this further below with reference to the chip which replaced it.
Exynos 7 Octa (7870) Specs
The Exynos 7 Octa (7870) comes with a Cortex-A53 1.6GHz Octa processor as its main processor. This CPU does not have a secondary processor so it will 
be for your more low end mobile phones. The GPU is also a pretty mid range GPU being a Mali-T830 MP1 GPU. The CPU comes with the standard HEVC (H.265), H.264, VP8 codecs and the playback is pretty good at Full HD at 60fps for encoding and decoding.
Camera capacity is 16MP camera both front and rear and it is dual camera capable with 8MP+8MP dual camera support. The built in modem is a LTE Cat.6 2CA which allows for 300Mbps (DL) as well as 50Mbps (UL) speeds. The memory on the phone is the older LPDDR3 933MHz which was not used in the following version of the chip. You can compare the current Exynos 7 Octa (7870) as well as the chip which came next being the Exynos 7 Octa (7420).
| SPEC | Exynos 7 Octa (7420) | Exynos 7 Octa (7870) |
|---|---|---|
| Series | Exynos 7 | Exynos 7 |
| Process | 14nm FinFET | 14nm FinFET |
| Multi-core | Octa | Octa |
| CPU (Primary) | Cortex-A57 2.1GHz Quad | Cortex-A53 1.6GHz Octa |
| CPU (Secondary) | Cortex-A53 1.5GHz Quad | None |
| GPU | Mali-T760 MP8 | Mali-T830 MP1 |
| Video | 4K UHD 30fps encoding and decoding | Full HD 60fps encoding and decoding |
| Codec | HEVC (H.265), H.264, VP9 (decoding) | HEVC (H.265), H.264, VP8 |
| Display | WQUXGA (3840×2400), 4K UHD (4096×2160) | WUXGA (1920×1200) |
| Camera (Rear) | 20MP | 16MP |
| Camera (Front) | 8MP | 16MP |
| Camera (Dual) | None | 8MP+8MP |
| Modem | None | LTE Cat.6 2CA 300Mbps (DL) / 50Mbps (UL) |
| Connectivity | None | GNSS |
| Storage | eMMC 5.1, UFS 2.0, SD 3.0 | eMMC 5.1, SD 3.0 |
| Memory | LPDDR4 1600MHz | LPDDR3 933MHz |
| Application | Smartphone, Tablet | Smartphone, Tablet |
