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FC0-FC2 680x0 Bus Signals Needed?

Trash80toHP_Mini

NIGHT STALKER
Yeppers, I know what you mean! :approve:

I've been ruminating on possibilities for the SuperDuo hack for something like ten years now! :-x

So far as a Video Card project for the SE/30/IIsi PDS goes: I find it difficult to believe that you'll need any more than the signals I've documented on the SuperMac IIsi PDS Adapter.

Sure as $#!^, if I were working on that IIsi PDS Adapter made specifically to support SuperMac's Video Cards, I'd have put those overvoltage noise suckers on every necessary line!

But then again, I'm just a . . . ;)

When it comes to those artifacts at startup: take a page out of the Radius Playbook. The DeclROM for every Video Card of theirs that I've used, or collected over the years, has thrown up a gray screen with the Radius Logo in the corner long before extensions load . . . or the Happy Mac hits the stage, for that matter . . .

. . . poof . . . no artifacts! }:)

 

Gorgonops

Moderator
Staff member
Just to clarify my comment about a "IIci-based ROM upgrade" what I meant would be to use the IIci's ROM as a starting point (since there's no point keeping an "unclean" ROM if the whole point is to raise the memory ceiling of the machine) but find and patch the part of the ROM that does RAM discovery and creates/loads the PMMU mappings so that in addition to looking at the built-in memory controller's address pool it recognizes the presence of an expansion memory card in the Nubus SuperSlot space and maps its banks into the appropriate locations in logical address space when 32-bit addressing is enabled. I didn't mean literally using the IIci's ROM as-is, because lacking a new discovery routine to locate and appropriately map the high memory at boot time it doesn't really buy you that much.

(In the sense that you'd still need to come up with a "ram-enabler" driver to wedge in early in the boot process and correct the mappings already loaded into the PMMU by the IIci ROMs, sort of a "MODE32-lite". That may or may not be cleaner/easier than trying to find the memory mapping code in the MODE32 extension and patching *that* so it does your expansion card discovery. Either is going to involve fairly deep hacking of binaries you lack commented source code to.)

One advantage I could see in principle of replacing the original ROM with a custom one paired to the expansion card would be that you could have the new ROM directly do whatever initialization is necessary to bring the card up without bothering to go through the Nubus/PDS declaration-ROM dance. Just have it do a simple sniff to see if the card is there and then either continue with initialization or crash to a Sad Mac as appropriate. Since we're dreaming here at this point you might as well also hack the video driver. Viola, no more screen corruption problem.

An obvious addition to this magic card would be an Ethernet port, of course. ;^) With that there really wouldn't be any need to make the card "well-behaved" enough to need a passthrough/pairing option with another board.

 

Trash80toHP_Mini

NIGHT STALKER
EtherNet SchmeeeetherNet! }:)

For the I/O Field of Dreams Card:

;) Design the card with the PBX Bridged '030 headers w/cable driver ICs on the corner for the 1400's T-Rex enabled PCMCIA Card Cage to implement PCMCIA WiFi, lowly EtherNet or any other available card option . . .

. . . with IR-Talk garnish! [:D] ]'>

This would be cable mounted to stick out the backplane plate of the SE/30 and IIsi along with your HD-15 Ribbon Cable Connector or, alternately, with the Card Cage sitting directly on the DreamCard's Headers and facing out the HDD Cubic of a 2300c or a 68k Duo . . . I'll figure out a place for the HD-15 cable, or a DIP Header Cable for VGA & ADB later . . .

. . . DreamCard in Sub-Terranian Hack Mode for the Duos, of course . . . :approve:

. . . while you're at it! :eek:)

p.s. you might want to take a peek at some of the interesting support features on the IIfx ROM to add in as well. I was surprised to see (presumably the IIci's Vampire Video) "Mac II Video" sitting on one of my pet IIfx's PseudoSlot Addresses in SlotInfo. The IIfx ROM's bits might provide for more and better slot interfacing/addressing capabilities! [}:)] ]'>

 

Bunsen

Admin-Witchfinder-General
Aaargh. A system crash just ate my reply. Re-attempting:

;) Design the card with the PBX Bridged '030 headers / for the 1400's T-Rex enabled PCMCIA Card Cage
OK, I can see the utility of that: you would have access to all those MacOS compliant cards - and more importantly their drivers - from back in the day. And at a guess, you would be re-using ROM code from the 1400 to enable the PBX/T-Rex in other machines, yeah?

But that seems almost like a parallel project to trag's, at least according to my poor tech reading skils. Aren't you going to have a clash of bus line requirements? Or would you be depending on the FPGA to arbitrate that?

Further thought: would it be possible to attach a new Cardbus cage (and chipset if required) directly to the FPGA and have it appear to the CPU bus as a PBX/T-Rex combo? Or does that lead you down the black hole of reverse engineering poorly documented ASICs? I mean, it's not as though dead & dying 1400s & 5300s for cannibalizing are unobtanium.

At worst, even if I can't map any of the extra memory as RAM, it sounds like dbraun (?) has figured out the basics of how to turn it into a RAM disk. So at worst, I could turn it into a big RAM disk and use it as swap space for virtual memory.
Correct me if I'm wrong (as usual :p ) but isn't that kinda good enough? VM appears as RAM to the OS and apps, neh? Is there some sort of overhead with using RAM-as-disk-as-VM-as-RAM - and even if there is, is it worth bothering about?

A wild brainfart appears: RAM on a PCMCIA card for RAM-challenged Powerbooks*. I know that we can already do much the same thing with CF, but is there any speed advantage** using RAM*** rather than flash?

* 190, 1400, 5300, 2400, 3400 - ie, those with Cardbus/PC Card slots, but proprietary & limited RAM.

** Presumably more so on Cardbus (PCI) than PC Card (PBX-T-Rex)

*** Raw ICs (w/wo sockets), or headers for SIMM/DIMM/SO-DIMM

 

Trash80toHP_Mini

NIGHT STALKER
And at a guess, you would be re-using ROM code from the 1400 to enable the PBX/T-Rex in other machines, yeah?
IIRC, the 2300 already has support for T-Rex/PCMCIA and IR-Talk in its ROM. The 2300c, the 1400 and the 3400 were developed together and released at the same time, they are all basically the same machine with the same ROM in three different flavors, IIRC.

The IIsi & SE/30 might need some help in that area! ;)

5300's won't work as donors, everything is on the MoBo as was the case with the 3400, not on a DaughterCard like the 1400's T-Rex/Card Cage/IR Subsystems.

It is a parallel project, but one that'd be a lot more :cool: than just ethernet as an add-on, IMHO. :approve:

 
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