kanecvr wrote:I'm going to go out on a limb here and ask a possibly stupid question (don't bite my head off) - could it be possible to include a PCI to ISA bridge chip on the same PCB and make a PCI version of this card? That would be kick-ass.
To my mind, one should take into account several aspects for such a solution.
1. How many PCI-ISA bridges can be functional simultaneously? For instance, if you put a discrete PCI-ISA bridge on the ARGUS and then install the ARGUS into a 440BX-based motherboard, you'll get two bridges. It wouldn't be a problem for multiple PCI-PCI bridges thanks to PCI bus specification providing for many PCI-PCI bridges. But with ISA?.. My guess that only one PCI-ISA can be reliably functional. However, once in my life I saw a little early PCI soundcard based on some ISA Crystal PnP codec (CS4235 IIRC) with some embedded PCI-ISA bridge! It was listed on TaoBao for some CNY 50, but I didn't buy it for some unknown reason. And given its age, it was definitely designed when merely all motherboards still had PCI-ISA bridges embedded into south bridges. So if we assumed that mentioned card could work, then multiple PCI-ISA bridges would not be an issue.
2. How will the PCI-ISA bridge handle DMA? I've read lots of info on different bridges from different vendors, working (or not working) with different chipsets (supporting DDMA, of course) with different sound cards. You know, final solutions always depend a lot on all factors. GUS can become very hard to handle even in a typical period correct environment, let alone such Frankenstein systems. For example, I know a guy from Russia who has successfully tested a GUS classic rev. 3.74 in some P4 motherboard (don't remember chipset at the moment) using some discrete PCI-ISA bridging expansion adapter based on an ITE bridge. But it was his second attempt - the first one was with a GUS PnP, and despite all his efforts he couldn't make it work. Neither could another friend of mine, who tried a GUS PnP on an industrial P4 system with an integrated PCI-ISA bridge. It seems that InterWave uses some ISA routines that are not used by GF1 and are not supported correctly on late PCI-ISA bridges (or late chipsets that still support DDMA needed for all these bridges to provide DMA on ISA bus).
3. How will the ISA bus be initialized? InterWave is a PnP device, and as such it needs some specific software initialization (carried out by ISA PnP BIOS or its driver), but will those support such bridges? Mentioned guys have managed to get some low level initialization software for the bridges, but again, no luck with InterWave.
4. Of course, such a card would be a real jewel both technically and esthetically, but will it bring any real added value? Being a resource-hungry device with lots of possible issues, it would be a real nightmare to configure due to the additional headache with the bridge. And yes, embedding another complex IC with two buses will turn this great project into a Duke Nukem Forever 😀
wbc wrote:Just a thought...
As I remember the prototype schematic and PCB layout is done by now so changing something in would be dificult […]
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Just a thought...
As I remember the prototype schematic and PCB layout is done by now so changing something in would be dificult, but:
A couple of weeks ago I upgraded my Sound Blaster AWE64 Value (CT4520) onboard RAM from 512kb to 2MB by replacing original (256k x 16 bit) EDO RAM chip by (2048k x 16 bit) chip from spare SIMM module. Despite of some differences in pinouts, it was possible without messing with wires because Creative put some 0-ohm resisors for pinout configuration:
picture cut out
So, it is possible to add (2048k x 16 bit) memory chip support to ARGUS? I think it can allow to put 4MB of RAM instead of 1MB just by two memory chips on board without external SIMM module, which might be sufficient for most Ultrasound\Interwave software (but not for huge and good sounding MIDI banks 😀)
If you need some info, I can help. 😉
AFAIK InterWave only supports 256Kb, 1Mb and 4Mb of RAM per bank. I guess, it is somehow related with its RAM addressing restrictions, but for this piece of rocket science I would suggest referring to the first pages of the thread for InterWave datasheets and RAM-related discussion.
So, I guess, the answer is negative. And again, what's the reason for such option? 1024K ought to be enough for everybody © in terms of classic GUS compatibility, and if you want more for your Windows-based applications, you can always find a 4Mb SIMM72 for next to nothing. Even a 16Mb SIMM72 shouldn't be such a problem thanks to InterWave supporting both FPM and EDO memory.