What controls the 640K DRAM video allocation?

[Nathan_A]

Does anybody happen to know how that 640k is carved off to provide DRAM video on the HDI-45 port? I'm relegated to using the DRAM video on my 7100/80 because I've loaded it up with:

• Radius Rocket Stage I
• Orange Micro OrangePC 290
• Apple Ethernet NB A/ROSE
• Reply DoM 7100 PDS

So that I could have a 68k & 486 class computer and a PowerPC & Pentium class (the DoM card has a Pentium Overdrive chip in it) all in one computer. Because I used up the PDS slot I can't use the HPV card for higher resolutions & bit depths. I can't use my PicklesXA card for video because I need the Ethernet NB card to give a dedicated network interface to the Radius Rocket.

The machine has 136MB of RAM in it, so I'm not going to miss another few hundred kilobytes to bump up the bit-depth that can be set for 832x624 or maybe allow 1024x768 (though I suspect that latter thing isn't only a function of RAM).

I suppose it's possible that 640K is set in whatever IC is providing the DRAM video support, but I figured it might also be something that's set in ROM or something like that?

 

[Byrd]

Dunno, but please post pics of this bad boy! Does the PSU handle it all OK?

 

[jeremywork]

Even if you could allocate more DRAM, I’m not sure the RAMDAC is set up to use the extra bandwidth.

One thought is to see if the Radius Rocket can make use of a SCSI Ethernet adapter. You’d lose A/ROSE, though in my experience it’s most useful to 68030 class machines. 040 Quadras tend to have enough CPU time to spare for onboard ethernet that performance isn’t impacted. Not sure about the Rocket though.

 

[Nathan_A]

Dunno, but please post pics of this bad boy! Does the PSU handle it all OK?

I finally got all my shelving and cabinets from IKEA to display most of my collection, so I've been setting things up and also taking pictures of various expansion cards I have too. Sooner or later I'll post them to a "Conquests" thread. It's been a hell of a last 6 months trying to make sure my company stays funded. The stress and time sink of which hasn't left much of the candle left to burn for fun stuff like curating my collection.

The power supply "seems" to handle it okay. I put that in quotes because there are some instabilities and inconsistencies that I haven't been able to properly diagnose. Sometimes the Rocket locks up immediately it boots, but I think this might be network software related. Sometimes Windows95 on the OPC 290 freaks out, but I think this is WDC video driver related.

That said, it could be PSU related.

 

[Nathan_A]

Even if you could allocate more DRAM, I’m not sure the RAMDAC is set up to use the extra bandwidth.

One thought is to see if the Radius Rocket can make use of a SCSI Ethernet adapter. You’d lose A/ROSE, though in my experience it’s most useful to 68030 class machines. 040 Quadras tend to have enough CPU time to spare for onboard ethernet that performance isn’t impacted. Not sure about the Rocket though.

Hmm, that's not a half bad idea. Yeah, I figured that the RAMDAC would be a limiter at some point.

Admittedly, I'd be a little bummed losing out on there being yet another computer and OS running in there (A/ROSE on the 68000).

Right now it's MacOS 7.1, Windows 3.11, A/ROSE, Windows 95, and MacOS 7.6.1

 

[mg.man]

Dumb(?) question... doesn't the 7100 have on-board e/net controller? Won't that be "as quick" as a A/ROSE-assisted NUBUS card? Am I missing something?

 

[Nathan_A]

Dumb(?) question... doesn't the 7100 have on-board e/net controller? Won't that be "as quick" as a A/ROSE-assisted NUBUS card? Am I missing something?

Well, in this setup the OPC 290 has a PCMCIA Ethernet card. The host Mac and the Reply DoM card share the host 7100/80 built-in NIC. Theoretically the Rocket can also use the built-in host Mac NIC, but that doesn't actually work in this case due to software & TCP stack incompatibilities.

So, the only way I can get the Rocket on the network with the rest of them is to dedicate it its own NIC. In this case the Nubus one.