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Posted Mon Feb 27, 2012 11:34 PM
Posted Tue Feb 28, 2012 8:36 AM
Does Level 1 have the ability to use bank switched RAM pages?
Posted Tue Feb 28, 2012 8:49 AM
Edited by Rybags, Tue Feb 28, 2012 8:50 AM.
Posted Tue Feb 28, 2012 9:56 AM
I checked your blog entry earlier, re PIA problems.
I guess you've probably worked it out, but you need to configure the data direction to properly control bank-switching.
Default is that all outputs are $FF which means OS ROM in, Basic out (PortB).
PortA is joysticks so you generally want them to be inputs.
To set each port for data direction config, write $38 into the PxCTL register, then write 1s to PORTx bits you want to be outputs.
Then set each port back to normal I/O by writing $3C into the PxCTL register.
Quick reminder about a the not well documented behaviour for PORTB banking:
bit 7 0 = Self-Test switched in, but only if OS Rom is also switched in
bit 6 0 = Missile Command @ $A000 but ony if Basic Rom is switched out
bit 1 0 = Basic switched in
bit 0 1 = OS Rom switched in, opposite behaviour for this bit vs all the others relating to Rom.
Posted Wed Feb 29, 2012 10:29 PM
Posted Thu Mar 1, 2012 1:04 AM
Posted Thu Mar 1, 2012 1:24 AM
Posted Thu Mar 1, 2012 2:44 AM
Posted Thu Mar 1, 2012 2:53 AM
Edited by Rybags, Thu Mar 1, 2012 2:54 AM.
Posted Thu Mar 1, 2012 6:13 AM
Posted Thu Mar 1, 2012 6:26 AM
I've been actively following this project, and I think that what you are doing is extraordinary!
Would you consider a MC68008 project, once this project is fully functional?
A MC68008 would really be the missing link for the Atari 8-bit; since 68000 assembly code for the ST, Amiga, Mac, etc. could be used. No rush, of course, I'm just interested in hearing your perspective on such an endeavor, as an engineer.
*(For those of you who are unaware of the MC68008, there is a very good MC68008 small computer primer here.)
Thanks for your dedicated work; I am truly amazed at what you've accomplished so far!
Edited by boisy, Thu Mar 1, 2012 6:27 AM.
Posted Thu Mar 1, 2012 8:13 AM
Thanks for the comments. Yeah, a 68K would be cool, but a little out of my league I'm afraid ...
Use a regular 68000, not the 68008... why put an artificial and unneeded limit on the thing before you even start?
and even better would be a 020 or 030... read the hardware ref's for them, and you will find out why they would be even easier to use...
Edited by UNIXcoffee928, Thu Mar 1, 2012 8:14 AM.
Posted Thu Mar 1, 2012 1:26 PM
Posted Thu Mar 1, 2012 9:47 PM
Posted Mon Mar 5, 2012 10:26 AM
Posted Mon Mar 5, 2012 5:41 PM
Posted Mon Mar 5, 2012 6:06 PM
Posted Mon Mar 5, 2012 8:05 PM
Posted Tue Mar 6, 2012 8:47 AM
Adding PBI won't make or break the project.
But it could greatly widen the market of potential users as some would like it just for the added PBI
You could have multiple config/price points:
- board with PBI, user swaps in their 6502, 6809 slot unpopulated
- board without PBI, user swaps in 6502, 6809 slot populated
- board with PBI + 6809, user swaps in 6502
A sticking point though is with the OS ROM slot. Not many people can force feed via the PC or build their own board with a pair of EProms.
Posted Tue Mar 6, 2012 9:27 AM
Posted Tue Mar 6, 2012 9:38 AM
Posted Tue Mar 6, 2012 2:04 PM
I don't think very many people will take advantage of a PBI. With all the small internal or cart based expansion options I don't see why you would need it for more than bragging rights.
And that's the crux here. Using the 6809 requires having a different ROM and that requires plugging and unplugging THAT, even though you can set jumpers to switch between CPUs.
Looking at the PBI here (http://en.wikipedia....l_Bus_Interface), if we are to get the signals purely from the daughterboard, we wouldn't have access to pins 2, 41, 43, 44, 46, or 49. How would a PBI connector with an incomplete set of signals be received by potential buyers?
At this point, I would opt for simple: a single daughterboard that just had enough room for the 6809, the timing chip and the PAL. I would imagine many Atari users of the Liber809 would have a spare Atari to dedicate just for the 6809, so switching wouldn't be that big of a deal, especially in light of the ROM swap that would be needed.
Posted Wed Mar 7, 2012 9:15 AM
Posted Wed Mar 7, 2012 1:28 PM
Posted Wed Mar 7, 2012 2:53 PM
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