1. SVGA Test and OSes
[SVGA TEST]
I think a DOS interrupt has been used to test if the SVGA modes exist. I think,
Dave Cuny's machine it keeps crashing. I have some ideas.
On a machine without that interrupt calling that interrupt may crash it so I
came up with the following Pseudo Code
BEGIN
Save Registers
Disable Interrupts
Read from mem the vector for the SVGA Interrupt (0000h:(IntNumber*4))
Enable Interrupts
IF Vector != NULL THEN
IF Vector != Error Interrupts Address THEN
Try the interrupt.
END IF
END IF
END
An unused interrupt is either set to NULL (INT 00h : CPU GENERATE - DIVIDE ERROR
) or re-vectored to the Error Handling Interrupt (INT 24h, I think). This may
be what's hanging Dave's system. Unfortunately there is no direct way to
[dis]enable interrupts in Euphoria, unless get_vector does it automatically. If
it doesn't then a com program might be called for. If get_vector disables the
re-enables interrupt the could then become
---<untested code>---
function check_interrupt( integer num )
sequence vector
integer val
val = 1
if num > #FF then
vector = get_vector( num )
if vector[1] = 0 then
if vector[2] = 0 then -- NULL Vector
val = 0
elsif vector[2] = #24*4 then -- DOS ERROR HANDLING
Vector (???)
val = 0
end if
end if
else
val = 0 -- Bad Interrupt Number
end if
return val
end function
---<end>---
Also according to one lot of information I have INT 4F (SVGA INT) is also the
SCSI Controller INT perhaps there is a conflict or your trying to ask the SCSI
controller to do SVGA things. This should be done all the time, so I suggest a
setup program.
[OSes]
I reinstalled Caldera Open DOS, ran several Euphoria programs and every thing
seemed to work fine. I didn't use any network support though as I don't have a
network.
Oh on the subject of OSes, if you want a simple OS, try the QNX OS Demo, it
fit's on a floppy. Including, HTML 3 Web-Browser with Modem & TCP/IP suppport
and Text Editor. It however doesn't have disk support, so you can't save, but
just to surf the web it's great as you just have to keep it on a disk, oh and
it can print as well, I think. It has a GUI for those who like that sort of
thing.
---
Sincerely,
Mathew Hounsell
Mat.Hounsell at mailexcite.com
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