Ricoh 5A22
Ricoh 5A22 is a microprocessor manufactured by Ricoh for the Super Nintendo Entertainment System (SNES) game console , which serves as the main processor. The 5A22 is based on the 65C816 from WDC (which was used in the Apple IIgs , for example ). The processors mentioned come from the processor family of the MOS 6502 .
Main features
In addition to the 65C816 core, the 5A22 also has the following components:
- Interface lines for the controller - port , both serial , and parallel access to the data controller
- An 8-bit parallel I / O port that was largely unused in the SNES
- A circuit for generating NMI interrupts ( non-maskable interrupt ) within the vertical blanking interval
- A circuit for generating IRQ interrupts at a calculated image position
- A DMA unit that supports two primary modes:
- Normal DMA, for block transfers with a data rate of 2.68 MB / s
- DMA within the horizontal blanking interval, for the transmission of small amounts of data at the end of each scan line , outside the active display time
- Register for multiplication and division
- Two separate address buses that control the 8-bit data bus : a 24-bit "Bus A" for general access and an 8-bit "Bus B" mainly for APU and PPU registers
power
The CPU uses a system bus with variable speed, the access speed of which is determined by the requested memory location. The bus is clocked at 3.58 MHz for non-access cycles and when bus B or most of the internal registers are accessed, and either 2.68 or 3.58 MHz when bus A is accessed. The controller ports of the serial registers only work at 1.79 MHz. The 5A22 works with around 1.5 MIPS and has a theoretical peak value of 1.79 million 16-bit additions per second.
Individual evidence
- ↑ Anomie: Anomie's SNES Memory Mapping Doc. Retrieved March 18, 2009 .