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Re: [N8VEM: 14330] Re: Announcing RomWBW v2.0 (finally)
Somebody knows more about programming than I do (and knows how to document
it properly).
I haven't done much with that N8VEM card - had to put it on hold for a
while.
Gerry Sherman
-----Original Message-----
From: James Moxham
Sent: Tuesday, July 24, 2012 6:46 PM
To: n8...@googlegroups.com
Subject: Re: [N8VEM: 14330] Re: Announcing RomWBW v2.0 (finally)
This is a fantastic document! I particularly like the diagram on page 3,
especially the little arrows in the memory going up. I that encapsulates
the whole idea, because you can see how this is going to make the TPA
bigger.
Theoretically, how far can you push the concept? Can all of CP/M be moved
out into other areas?
On the Propeller chip there are a number of SD drivers and the ones that
work with more cards (particularly the newer ones) are generally larger.
Approx 16k of Spin and Pasm. At the end of the day though, the code ends
up toggling 4 pins and so there is no reason the code could not be in Z80
assembly. A problem with that on a standard board is it takes away more
TPA space, but RomWBW provides a way around that.
I'm playing around with some $15 full color touchscreen displays (240x320)
that have an SD card included as a bonus, and these are working well with
the Propeller. These are advertised as "8080 compatible" and indeed, the
code to drive them is very much old-school 8080/Z80. 8 bit bus and some
control lines. I even managed to squeeze an 80x40 display onto the screen
using a very tiny font. Lots of possibilities for "touchscreen CP/M" (both
text and also graphics if you wanted to).
Again, the big barrier to such an idea is the code space needed (maybe
another 16k of Z80). And again RomWBW solves that problem.
Some intriguing possibilities.
Just to double check, there is no need for code to change the bank to
anything other than 32k/32k?
Cheers, James Moxham
On Wed, 25 Jul 2012 00:13:28 +0930, Wayne Warthen <wwar...@gmail.com>
wrote:
I am attaching a preliminary draft of a document that attempts to
describe
the RomWBW architecture, particularly the bank switching mechanism. This
has a long way to go, but might be useful in it's present form for some.
I
would be very happy to get feedback on this. I am publishing this as a
PDF
to ensure it is easy for everyone to view. However, I will include the
Word Document source in the ROM distribution in subsequent releases in
the
hope that others may contribute to this.
Thanks!
Wayne
On Monday, July 23, 2012 8:59:43 AM UTC-7, Wayne Warthen wrote:
Sure, I will put together a bit more documentation of the banked BIOS
architecture and post that as soon as I can (probably tonight).
In the meantime. There are two documents in the Doc folder of the
distribution that are also helpful. One is called "HBIOS Functions.txt"
which documents the new hardware bios function calls. The other is
called
"BankedBIOS.txt" which provides some documentation of the BIOS.
Thanks!
Wayne
On Monday, July 23, 20y 12 4:02:38 AM UTC-7, lynchaj wrote:
Thanks Wayne! Wow! That's awesome! Very nice!
Using ROM banking in the CBIOS is really great and should free up some
TPA memory for CP/M programs.
Would you please elaborate on how this works?
Thanks and have a nice day!
Andrew Lynch
On Jul 22, 9:10 pm, Wayne Warthen <wwar...@gmail.com> wrote:
> *RomWBW v2.0 (aka, the Al Di Meola release) has just been posted on
the
> N8VEM Wiki. I would like to thank all of the folks that provided
feedback
> and testing on the beta versions.
>
> The distribution can be found in the RomWBW folder<
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder�m=RomWBW>which
is
inside of the N8VEM
> Firmware and Registry folder<
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder�m=N8VEM%20...>
> .
>
> This is the new banked version of the BIOS which significantly eases
the
> memory constraints inherent in the Z80 architecture.
>
> Please note that the ROM and RAM disk memory layouts have changed to
> accommodate the memory banking. If you have a battery backed RAM
disk,
it
> will need to be reformatted after this ROM is installed.
>
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