From: muta...@gmail.com
On Tuesday, July 6, 2021 at 9:11:11 PM UTC+10, Rod Pemberton wrote:
> > And now that I know that the BIOS even provides an
> > INT 14H, I'm a very happy camper, because my eyes
> > light up and I see "SeaBIOS and bluetooth!".
> By Int 14h, you mean BIOS serial I/O?
Correct. And at the level of INT 14H functions 1
and 2, there isn't even a concept of serial, is there?
They should have provided functions that take a
block as well, instead of individual bytes. But
nevermind.
INT 14H function 0 has echoes of RS232 but I
will relegate that to anyone who uses the
"MODE" command, which won't make sense for
a bluetooth connection. Basically when someone
opens COM1 it should be happy to inherit the
already-set setting.
> Are you saying you intend to enable the A20
> line via the BIOS Int 15h, AX=2401h call, so
> as to make PDOS hardware independent? ...
Yep, exactly.
> I.e., it seems like you're saying you're
> eliminating enabling A20 via port programming.
Yes.
> If so, then
> a) that's a very bad idea, and
> b) I didn't give you that int.
You're right. Sorry Rod, thanks Scott.
https://groups.google.com/g/alt.os.development/c/ehyG4KrMQgs/m/fvxdXa4lAgAJ
C:\devel\pdos\src>git show a1a0be61d1d613e39265234eeb1d683c6621d6af
commit a1a0be61d1d613e39265234eeb1d683c6621d6af
Author: Paul Edwards
Date: Sat Jul 21 17:22:12 2018 +1000
additional method of switching on A20 line
diff --git a/src/lldos.asm b/src/lldos.asm
index e86bd6d..bf0e220 100644
--- a/src/lldos.asm
+++ b/src/lldos.asm
@@ -151,6 +151,8 @@ a20e_ii:
jnz a20e_ii
mov al, 0dfh
out 060h, al
+ mov ax, 02401h
+ int 015h
ret
a20e endp
> James and I found serious problems with the
> BIOS A20 functions we tested, which mostly
> failed for 10 motherboards. The keyboard
> and PS/2 port enable methods work, except
> one motherboard which pre-dated PS/2.
Ok, given that I'm not actually selling PDOS/386
commercially, I have the ability to be "purist" now
that I know what I want.
So at some level I will just tell people to get a new
BIOS or change the code themselves.
But at another level, I like Scott's code. First he
checks to see if A20 is already enabled. Only then
does he do the next step, and the very first thing
he tries is the INT 15H. So it is only if that fails to
do the trick that he starts manipulating the
hardware.
So, we'll see what happens. Maybe I can provide a
byte offset for people to zap if they want to
continue on, and manipulate hardware. Or maybe a
zap for purists to switch off the hardware fallback.
At some level I'm just going to tell people to not buy
a computer unless it can have SeaBIOS flashed, at
least if they want to run PDOS/386.
And obviously, given that it's public domain, people are
free to find a better derivative than the one I'm providing.
I'm expecting commercially-minded people to produce a
commercial-quality product, not me (unless I decide at a
later date to be a commercially-minded person - but
quite frankly I think I'm more likely to become a serial killer -
my sister once said that computers were invented just in
the nick of time otherwise I would have been an axe
murderer).
http://www.ratman.biz/archive/young_ones/flood.html
Vyvyan: It's a potion I've invented where when the patient drinks it he turns
into an axe-wielding, homicidal maniac! It's basically a cure. For not being
an axe-wielding, homicidal maniac. The potential market's enormous!
BFN. Paul.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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