Building a computer

Sun Nov 27 15:23:51 2016

In high school, some friends and I had a project to build a computer ourselves. We didn't get very far at the time. I've been playing around with an arduino the last few days and the idea has come back to mind.

So I started looking around at how I might build a computer from relatively discrete components. Not down to the transistor level, but ideally with each major subsystem being separate. We had a 16 bit computer in mind, as we'd had Commodore 64's, and thought a 16 bit computer would be cool.

I've looked around, and there don't seem to be all that many actual 16 bit processors around. Several 16 bit microcontrollers. I'd like to be able to use external ram, which means that the CPU chip will need to have external memory address pins. So for this post, I'm meaning microcontroller to mean that there is no direct support for external memory.

I'd also like everything to be available in PDIP packages to make the design and prototyping easier.

What I've found so far:

Processors

http://www.ip-extreme.com/IP/16bit_microprocessors.shtml

CR16: doesn't seem to be actually available

Looks like one is available: http://www.mouser.com/ProductDetail/Texas-Instruments/CP3BT26Y98NEP-NOPB/?qs=7X5t%252bdzoRHBr3m4jqM4nLQ%3d%3d $27

C166S: possibly available, a hybrid processor, with embedded ram, but an external databus. Seems to be from $10-$25. These are available in TQFP or LQFP packages.

http://www.infineon.com/cms/en/product/microcontroller/16-bit-c166-microcontroller/xc2200-family-body/channel.html?channel=ff80808112ab681d0112ab6b655c0807#ispnTab3

documentation terrible

[W65C816S]: This is a 6502 with extensions for 16 bit registers and a 24 bit memory bus. It seems heavily banked into 64K regions. I'd also like to use a cleaner 16 bit CPU.

The following have no support for external memory

• [MSP430]

Posted in / hardware