Electronics, coding and hacking. And ADD.

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6502 plans revealed


My apologies for not updating the blog as frequently as I once promised to. I'm busy these days as I'm coding a part for a C64 demo, moving to a new house, and taking exams in electronics, in addition to entertaining my wife and kids. So, needless to say, there's not much time to play with the toys. I've been thinking a lot about the 6502 computer, though, and I'm going to let you in on the oh-so-secret plans right away:

CPU and memory: Not surprisingly, it will feature a 6502. More precisely, a Rockwell 6502 CPU accompanied by 32K SRAM and a massive 32K ROM. The ROM will share its address space with the items following.

GPU: I'm planning to do the GPU myself, quite possibly in FPGA, but for now I'll settle with something pre-made. I've ordered a few NOS TMS9928's - old arcade video chips. They have 16K of "internal" RAM and can easily be mapped into the address space without too much hassle, and they also feature multiple screen modes. Yes, even bitmap modes, which make them ideal for my system.

Disk controller and I/O: The disk controller will be performed by an ATmega16 with an SD card interface. That's more than sufficient for this little thing. This controller will also deal with the PS/2 keyboard and RS232 port.

Audio: I'm very inspired by the Micro SwinSID (6581 SID clone), which is based on an overclocked ATmega88. Choosing this approach, and mapping it into the right addresses, I get access to 40K+ SIDs, ready to be played on my system.

Then there's also a CPLD board and programmer on the way from Hong Kong. I think it's time I started learning that stuff, as I've come to the realization that not everything can (or should) be solved using micro controllers. This stuff is reserved for the lazy days, though.

So, those are the plans. Everything will exist in the form of a breadboard project until I get it working just right....


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