More on ISA cards / Flashlite 186 SBC

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The discussions here about ISA cards have brought to mind a possible
solution to a problem I have; how to make a little board that can do
640x480@15/16bpp video on analog VGA, with a build cost of <=$100.
Production volumes would be low - 10pc order runs, and probably no
more than 200-300 total production.

Specifically, what I'm wondering about is taking a board like the
Flashlite 186 (www.jkmicro.com/technicalinfo/ti_flashlite186.html) and
putting an ISA-esque interface on the processor bus port, and using an
old ISA SVGA card. The reason for picking an x86 is so that I can
install the card's int 10h BIOS hook and use VESA VBE calls to set the
desired graphics mode.

Does this sound feasible? Any obvious, truly stupid thing I've
forgotten?

-- Lewin A.R.W. Edwards http://www.zws.com /
Learn how to build high-performance embedded systems on a budget!
(Amazon.com product link shortened)

Re: More on ISA cards / Flashlite 186 SBC

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In my time at Arcom Control Systems, we did a lot of work with PC
peripherals connected to 80186/80188 boards, and we created a product
(SourceGraph) to drive specific VGA cards.

You could strike it lucky with a random VGA card, or you could find it
impossible to get working. It is amazing how much PC-specific stuff is in a
VGA BIOS - as a board manufacturer, we were able to get access to some BIOS
source code, so we knew eaxctly how PC-dependant they were. The 80186 is
PC-code compatible, but key peripherals (timers & interrupt controller) have
different addresses and functionality, and the memory map probably isn't the
same as a PC.

To give one trivial example, we had a VGA board that worked fine in text
mode, except that all numeric characters 0-9 were corrupt. It turned out
that it was loading the numeric font (but not the text font!) from the old
MDA font located in the motherboard BIOS, so we had to fake this at the same
address in the 80188 memory space.

I think the reduced production costs could be overwhelmed by increased
development costs - and who's to say that the ISA card you buy today will
still be available tomorrow?

Jeremy Bentham
Iosoft Ltd.



Re: More on ISA cards / Flashlite 186 SBC
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Then you're the gentleman to whom I need to speak :)

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I didn't think of issues like that. Hmm. Well, I still don't think
this precludes my approach. I don't actually want any of the card's
BIOS functions - not even text output. I have my own engine for all
that. The ONLY use for the card's BIOS would be to set the video mode
to a 640x480x15/16bpp mode. I am assuming that any ISA card I can find
has its aperture control registers well-enough documented in XFree86's
sourcecode for me to be able to write my own bank select code (see
below)

I've reverse-engineered VGA BIOSes and my experience is that it takes
1-2 weeks to turn a 32K BIOS into a quality, commented,
re-assemble-able piece of sourcecode. I don't want to do that.

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Well, I'm sure it won't be. Let me elaborate on my fiendish master
plan: I want to use the ISA bodge job for market-test purposes. The
product in question is experimental; we don't know how it will go
across with consumers. I wouldn't anticipate making more than 25-50 of
these devices with that bodge. I would think I can source that number
of fairly similar cards. I was thinking of using, say, Trident
8900-series cards, which are *largely* intra-family code-compatible
(certainly the stuff I'd need to program is the same amongst the
8900C/CL/CX/CXi).

The EVB for the SED1354 is also an ISA card. So once I have the
hacked-up version working and shipping, I can get the SED1354's EVB
working using the same hardware. Once THAT is working, I can make a
small custom PCB with a 1354 on it, to stick on top of the Flashlite.
That custom board would be [reasonably] producible, and it also gives
us a couple of other benefits.

Re: More on ISA cards / Flashlite 186 SBC
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in a
BIOS
will

Wonder if the VGA related emulator code in the Bochs project would be of any
use?



Re: More on ISA cards / Flashlite 186 SBC
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Not sure exactly what use it would be... because whatever chipset I
use will have special hidden registers required to set those SVGA
modes. But anyway, I've decided to give this project a try. I'm
sitting on my hands waiting for the Powers that Be to call JK with the
company credit card so I can get the EVB.

It also kind of hinges on how long the "186-ish" CPU on the board will
take to run my code. I need hands-on testing.

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