[Coco] 6309 microprocessor project 01-13-2004

[John Collyer]

6309 microprocessor project.

Hello,

I been real busy lately and been working on the emulator.  It will be a
win32 app and will only work with virtual *.dsk and *.vhd.  This way I'll
not have to worry about making any drivers for Windows XP/NT.  The work is
progressing but kind of slowly.  I am still only able to see how it'll work
in my head because there is nothing to run yet, but I had to start
somewhere.  Eventually I will have gathered up enough code to see something
working.  I am mulling over the memory issues now. I want to have the best
memory functions I can get.

If I keep a virtual memory extent (64K) and change the page number pointer
this will give me a easy way to keep track of the memory.  But, I'll have to
do extra work in the GetByte PutByte functions.  Like I'll have to get the
pointer to the 8K page and then get the byte from memory, or I can keep a
dedicated 64K memory image.  When I need to change the memory because of
writing to the MMU register, I will only need to blast the 8K memory to the
dedicated memory image.  This method depends on the speed of blasting the 8K
of memory.

I can't decide which one of these would be the best choice.  The question is
Getbyte and PutByte are called constantly so they should be the quickest.
But with this method (memory image of pointers) you have a nice way of
tracking everything.

With the other method changing the memory might happen at a much slower pace
then GetByte or PutByte do since writing to the MMU registers should not
happen as often as GetByte or PutByte do.  What you think?

I was wondering about what the emulator lacks in making Sockmaster's demos
work?  Is it the horizontal/vertical offset registers or is it more then
just that going on?  Any insights into why Jeff's emulator does not run
Sockmaster's demo appreciated.

John Collyer