LC PDS card

[Macdrone]

Finally trying to take some pictures and post what peeps have asked for. Here is the start.






Now something is rattling in the crystal ecliptek box so I guess I would have to get a new crystal before I do anything correct? Whats more is its a 68020 with FPU, I understand it will add an FPU to the machine but will that make it better? 68020 with fpu does that trump 68030 without FPU? Will this need drivers (if I can even find a crystal)? No makers marks only text other than machines its for are f2t-b9a 94v0 15-94.

 

[TheIanMan85]

Apple says here that there was a 3rd party FPU upgrade option for the LC and others listed on the card. I'm having trouble locating the make and model of this exact card, but I'm searching the web. Low End Mac references lots of upgrades, but none with an '020.

 

[Macdrone]

Ya I couldn't find anything on it, but without a new crystal as I am sure nothing is supposed to be loose in it, it will need that at a minimum. But if the 020 at 25 MHz beats the 030 because of the fpu might be worth it.

 

[olePigeon]

There are quite a few LC-PDS ethernet cards that also double as a FPU upgrade (has an open socket for a 68882.)

 

[Macdrone]

It's not an Ethernet card and it has a 68020 with separate fpu.

 

[olePigeon]

Oh, I know that, I was just making a comment regarding FPU upgrades for the LC. It's probably cheaper and easier to find an ethernet card with the FPU socket than trying to find just an FPU upgrade.

 

[Charlieman]

The silk screen labelling on the card makes no sense. Why put a 68020 processor with FPU into an LCII?

 

[uniserver]

yes, for some reason i do not understand this upgrade.

other then…someone swapped out the 68030 cpu / 68882 FPU, and put that 68020 / 68881 fpu in there.

maybe someone upgraded a Mac II with chips from this card.

 

[bbraun]

It's a 25MHz 020. The LCII had a 16MHz 030. This card is faster.

The 030 added MMU, burst mode, an addition 256bytes of data cache, and a slight increase in instruction execution time ("more done per clock cycle"). For most users of the LCII, the MMU wasn't used, the LCII's memory controller didn't support burst mode AFAIK, so you're left with the data cache and a slight per-cycle performance increase in the 030.

This turns my stomach to do such coarse calculations, but I'm doing it anyway to demonstrate. The 030 is rated at 18 MIPS @ 50Mhz. The 020 is rated at 18 MIPS @ 33MHz. So 030 at 16Mhz is 5.76 MIPS and the 020 at 25Mhz is ~7.6 MIPS. So, in practical terms, the only thing being lost is the 256 bytes of data cache, and trading it for ~25% faster execution.