WDC 65C832
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Author:  BitWise [ Thu Feb 19, 2015 1:22 pm ]
Post subject:  WDC 65C832

I've long wondered what the mythical 65C832 would be like to work with so I've decided to make it the subject of my next emulation. My assembler already has support for all the WDC family including the '832. Even if the 32-bit features of the device prove useless it should function as a pretty good 65C816.

I've managed to find some PIC32MZ development boards with 2MB of flash and 512K of RAM on chip which run at the full 200MHz/330DMIPS. I think this emulation will be coded in C rather than assembler and it might be fun to include a DMA+SPI generated VGA display.

Parts have been ordered and should arrive shortly.

Author:  Tor [ Fri Feb 20, 2015 2:30 am ]
Post subject:  Re: WDC 65C832

That will be interesting. I'm looking forward to what you find out. I recall having a "that sounds too complicated"-feeling when I read the datasheet a long time ago. I can't recall what that was about exactly, but I took a look at the datasheet again now and there are 24 addressing modes.. nearly as bad as the 28 address modes of a minicomputer I wrote an emulator for, some years ago. After implementing that I understood why the real hardware was so slow (relatively speaking). Just decoding the modes couldn't be done fast, even in hardware. And, as I implemented my emulator by letting real compiled code run through the emulator until it ran into something not implemented, I soon realised that compilers simply don't use all those modes. They use a subset which, when combined, can do everything.

Of course the 65C832 also incorporates 'c816 and 'c02 emulation modes.. and some of those addressing modes come from there. But I'm sure you'll have a lot of fun doing this and I'll definitely be interested in how it works out!


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