A 68060 does not really pique my interest anymore. I did some research into the idea, but apart from the work involved, the fact that code optimized for the 040 is not optimized for the 060, you would likely see a minimum speed boost... And where could I find an 060 compiler (which runs on the Mac) to write my own programs? I am looking at making a memory card which allows the system to run full bore at zero wait states (RAM and ROM). Think of it as a cache card on steroids. There are a couple of problems, one of which is that the memory is not cheap and I have already dropped a bundle getting a stick of high speed SRAM (0 wait states up to 50 MHz and 8 MB worth if I remember correctly). This surely will not be sufficient for any real-world application, but it will show the maximum performance of the system.
My current plan is to make the PDS card first (those connectors were IMPOSSIBLE to find - apparently Apple was the only company which used them and since the Quadra is long gone...), then use the SRAM to shadow the ROM and make my modifications in the SRAM for testing purposes. The advantage of the SRAM is that any changes will remain in the memory between reboots and I will have the card (once programmed) replace the ROM on boot. Once I am confident that my mods work as expected I will make a ROM SIMM card blank, burn some PROMs and make a ROM SIMM. I am not willing to remove the ROMs from the motherboard and replace them as I am concerned that it may take a few attempts to make a good ROM replacement and Apple tends to make very tender PCBs (they do not take kindly to excessive re-work).
I have been doing electronic system design for years (it is my profession) and while the ROM mods do present a challenge, I feel confident it is quite doable. My coding skills are almost exclusively assembly language (for numerous processors) as I find high level languages too cumbersome and limiting. As to my current board mods... I have replaced the SCSI and ethernet controllers. The new features are simply waiting for some code to release their potential (along with new crystals).
Thanks for the info on the ROM SIMM pin-out. I will need to do a full mapping of it before I make a replacement, but that comes after the PDS card. I only have time to do this sort of work in the winter (my summers are far too busy), and since that time is approaching... :-)
The memory bug I mentioned has to do with sticking in 256 MB of RAM (anything less is okay)... something funky happens, but I cannot remember what!
Derek
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