imported>RJFJR: /* Memory mappinghttps://github.com/MiSTer-devel/TurboGrafx16_MiSTer/blob/master/docs/HuC6280%20-%20CMOS%208-bit%20Microprocessor%20Hardware%20Manual.pdf */ move ref out of heading

2025-04-15T23:37:34Z

Memory mappinghttps://github.com/MiSTer-devel/TurboGrafx16_MiSTer/blob/master/docs/HuC6280%20-%20CMOS%208-bit%20Microprocessor%20Hardware%20Manual.pdf: move ref out of heading

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{{Short description|8-bit microprocessor}}
{{more citations needed|date=April 2025}}
[[File:HuC6280A 01.jpg|right|thumb|Revised HuC6280A]]
The '''HuC6280''' [[8-bit]] [[microprocessor]] is Japanese company [[Hudson Soft]]'s improved version of the [[WDC 65C02]] [[central processing unit|CPU]], an upgraded CMOS version of the popular NMOS-based [[MOS Technology 6502]] 8-bit CPU, manufactured for Hudson by [[Seiko Epson]] and [[NEC]]. The most notable product using the HuC6280 is [[NEC Corporation|NEC]]'s [[TurboGrafx-16]] [[video game console]].

==Description==

The HuC6280 contains a [[WDC 65C02|65C02]] core which has several additional instructions and a few internal peripheral functions such as an [[interrupt controller]], a [[memory management unit]], a [[timer]], an 8-bit parallel I/O port, and a [[programmable sound generator]] (PSG). The processor operates at two speeds, 1.79 MHz and 7.16 MHz.

A slightly revised '''HuC6280A''' was released and used in the PC Engine CoreGrafx and [[PC Engine SuperGrafx|SuperGrafx]]. This revision reportedly fixed some minor audio issues in those systems.

==Memory mapping==
Source:<ref>https://github.com/MiSTer-devel/TurboGrafx16_MiSTer/blob/master/docs/HuC6280%20-%20CMOS%208-bit%20Microprocessor%20Hardware%20Manual.pdf</ref>

The HuC6280 has a 64 KB [[logical address]] space, but a 2 MB physical address space. The HuC6280 uses a [[Memory Management Unit]] that splits the memory space into [[memory segment|segments]] of 8 KB.
Each logical 8 KB segment is associated with one of 256 physical 8 KB sized segments. This can be set up with an 8-bit register (MPR0-7) that contains the most significant eight bits of the address of the 8 KB [[memory segment|segment]] in physical memory. Thus the logical 64 KB address space can be overlapping, continuous or scattered in physical address space, depending on the eight MPR registers.

Two special instructions are used to access these registers:

<code>TAMi</code> - transfer the content of the accumulator (A) into an MPR register (0-7).

<code>TMAi</code> - transfer an MPR register into the accumulator.

==Sound generator==
PSG-styled [[wavetable synthesis]] provides six sound channels, which can be conveniently paired according to the functionality they provide:

0-1 - Waveform playback
Frequency modulation (channel 1 muted)
2-3 - Waveform playback only
4-5 - Waveform playback
White noise generation

Waveform playback is the most common and allows a 32-byte, 5-bit unsigned linear sample to be played back at selected frequencies. [[Frequency modulation]] takes this one step further, allowing the playback frequency to be dynamically adjusted according to a specified pattern. [[White noise]] is used to simulate percussion instruments and effects, such as explosions, by means of a pseudo-random [[Square wave (waveform)|square wave]].

Alternatively, each channel can be individually switched to "Direct D/A" mode in which the programmer can send data directly to the sound mixer, allowing more complex sound patterns to be generated, such as speech. Inevitably, this requires more programming effort and CPU time.

==References==
{{Reflist}}

==External links==
*http://shu.emuunlim.com/download/pcedocs/pce_cpu.html
*http://www.magicengine.com/mkit/
*http://www.interlog.com/~daves/pce_info/info.html
*https://www.copetti.org/writings/consoles/pc-engine/

{{MOS CPU}}
{{NEC video game consoles}}

[[Category:65xx microprocessors]]
[[Category:TurboGrafx-16]]
[[Category:Hudson Soft]]

Hudson Soft HuC6280 - Revision history

imported>RJFJR: /* Memory mappinghttps://github.com/MiSTer-devel/TurboGrafx16_MiSTer/blob/master/docs/HuC6280%20-%20CMOS%208-bit%20Microprocessor%20Hardware%20Manual.pdf */ move ref out of heading