Wanted: 68040!

[Argus]

As Dave Haynie could probably explain better, the chip ram and fast ram on the 32-bit Amigas was designed to interface with the 68030 chip cycles (which was the designated cpu at the time Dave was designing the A3000).  Adding a 68040 or a 68060 in asynchronous mode via the fast slot changes this relationship.  The A3640 for instance was notoriously slower at accessing the motherboard fastram on the a4000 (and A3000) due to this difference in cpu cycles and lack of burst mode capability.  Phase5 iirc added special hardware onto all of their 040/060 boards to replicate in hardware the interface of the accelerator card with a 68030, at least for chip ram access.  Thus, if you run an AIBB or similar check you'll find the Phase5 boards outperform other cards with respect to chip ram access speeds, which is key when talking about how fast the AGA chips are going to go.  Other manufacturers (GVP, Macrosystem, etc.) didn't fully implement this or ignored it altogether, opting instead for the fastest accelerator ram-to-cpu speeds.  Thus, they generally outperform the Phase5 boards on fastram (that is RAM physically on the accelerator) speeds, which helps more if you are talking about graphics cards or zorro card speeds rather than the AGA chips.  Also, I believe GVP is the only company that really worked on cpu burst cycles to the motherboard. There is a jumper on the GVP4060 board which purports to allow burst cycles to the motherboard, but I'm not sure if this actually works.  Dave or Greg Berlin (who designed the A3640) could explain this better, because the A3640 was compromised as a quick design to get a cheap 040 board ready for the A3000 and left out burst, 68030 async logic, etc.

[Argus]

alexh wrote:
@Argus

Interesting, but benchmarks on Amiga Hardware Database show that the CSMKIII (& CSPPC) has better fast RAM performance than any other card.

The WarpEngine was not included in the test but it would have to be something special!

That's probably true, I was thinking of the comparison between the original Cyberstorms (MkI&II) with the GVP and Macrosystem boards.  Phase5 introduced 64-bit interleaved Fastram with the CyberstormMkIII/PPC boards (that's why you need to install matched pairs of SIMMs on these two boards).  The 64-bit memory design has to do with the PPC604 chip used in the CyberstormPPC iirc and that most likely explains the speed difference over the earlier generation boards in pure Fastram access.  But for any of those who own the Phase5/DCE 2060, Cyberstorm MarkI/II, Blizzard 1260 or BlizzardPPC, you have a 32-bit memory interface with your 68060 and pure Fastram speeds are more than likely eclipsed by the GVP and Macrosystem designs...not that you'd really notice as the difference is nothing like the problem with the A3640 and m/b RAM.  But AGA chipram speeds will always be faster with a Phase5 board, if that's important to you.  I honestly don't know much about the Quickpak or Apollo boards; I've heard they have their own unique qualities, EDO RAM, etc. (which in the case of the Apollos can make them finicky about the SIMMs they'll work with).

One last thing, the GVP4060 definitely can't use EDO SIMMs, you need FPM modules...save yourself the heartache... :-)