On Sat, 10 May 1997, Mr. Self Destruct wrote:
> On Fri, 9 May 1997, Paul E Coad wrote:
>
> > I've been thinking about this as well. I did a some searching last year
> > and came up with a few kits for sale, and a few sites with build your
> > own computer information. Are you planning on building from scratch,
> > from plans, or kit?
> >
>
> I wanted to build from scratch (i.e with Radio Shack/Jameco/scraps and
> pieces, etc.)
>
> Nothing big, just something small, with maybe a floppy and a serial port
> for a terminal.
>
> > The kit toward which I am currently leaning is the Southern Cross 1.
> > It is a Z80 based SBC kit. Further information can be found at:
> >
> > http://kitsrus.com/sx.html#sx2
>
> hmmmm, maybe Ill check that one out!
>
> Les
Hey, so have I! I want to build a 6502 because
1. I already have a KIM and a SYM board 8-) for debugging.
2. I know the 6502 pretty well.
3. I have a 6502 Assembler wtih macro and structure support.
4. I have a 6502 Run/Single step emulator with programmable hardware
emulator.
5. It is an extrememly easy processor to interface with.
3 and 4 ain't fast but they do work 8-) on almost everything.
I think 5 is the most important. The same can be said for all the old
8-bitters tho.
For what you want, I would suggest a 6502, xtal, a couple of resistors
and caps, a 6522, 2-32K Static RAM chips and 1-32k EPROM. Since the 6502
is memory mapped IO, you would lose the memory wherever you put the IO
page but with a 74688? you could map any single or multiple 256 byte hunks
to IO real easy. My original thought was to use the reset line to switch
the ROM in and out of memory space so boot up would be to copy ROM to the
lower 32k and then recopy it to the upper 32k after the RAM is switched
back in. I think this is pretty standard stuff.
I have even thought (a little) about using PICs for IO devices and letting
them use IIC (I2C) to talk out one serial port to multiple devices. This
would be for the serial devices only, I would probably keep the 6522s for
parallel stuff (disk drives). Xebec used to make a Hard Drive controller
that would talk to any computer with an 8bit parallel device - don't know
IDE drives but I remember reading several companies do that for *newer*
computers. The problem being raw speed.
BC
Received on Sat May 10 1997 - 14:39:41 BST