53C80 Experiment

[trag]

The datasheet for the Logic 53C80 claims

It is pin and functionally compatible with the NMOS NCR5380, while offering up to a 2.5x performance improvement, 10x power reduction, and lower cost. Replacement of the NMOS 5380 by the LOGIC Devices L5380/53C80 will result in an immediate transfer rate improvement due to REQ/ACK and DRQ/DACK handshake response times up to 5
times faster than previous devices.

Is this a big deal, or just the normal improvement one gets by switching from NMOS to CMOS (5380 vs. 5C80)?

It seems like it would be interesting to do before/after SCSI performance comparisons on a Mac II family machine. Thoroughly benchmark the performance. Replace the SCSI chip with the Logic version, and test again. Compare.

Also leaves open the question of whether later NCR, SYMBIOS, LSI Logic or AMD parts have the same improvements. I haven't been able to find an LSI Logic datasheet for the 53C80 to check.

LSI Logic ended up owning NCRs semiconductor group after they were spun out and after they spent a time as SYMBIOS.

Note that Logic and LSI Logic are different companies.

I haven't seen stock of the Logic version anywhere except utsource and because of a bad experience I'm not willing to order from them. Otherwise I'd try this.

So who wants to do this experiment?

Or order me some L53C80 the next time you do a utsource order...

https://www.utsource.net/itm/p/11998118.html

 

[Kai Robinson]

I actually have some of these

 

[trag]

I actually have some of these

If you perform this experiment, please let us know.

 

[max1zzz]

I actually have some of these

Are there any random parts you don't have?

 

[Kai Robinson]

Are there any random parts you don't have?

Uhm.... No!

 

[trag]

@Kai Robinson But do you have any 343S0182 laying around?

These are the PCI arbiter chip used with the Bandit (343S0020) on the first generation PCI PowerMacs. I can find the Bandits, but no one seems to have thought that scavenging the associated arbiter was important. Can't use one without the other... And I've actually seen boards with failed arbiters and not yet any boards with failed Bandits.

We need a way to collect all the dead PM7200 boards with cracked PPC601s before they go to recycling...
Those each have a Bandit/arbiter chip(s).

 

[TheJ]

Just looking at my SE/30 (which might need a new scsi chip).
I have two; one uses an AMD 53C80 and the other uses an NCR 53C80.


As for dead boards for parts, maybe a new section on the forum is needed for "Part Sales & Collection".

 

[Kai Robinson]

Just looking at my SE/30 (which might need a new scsi chip).
I have two; one uses an AMD 53C80 and the other uses an NCR 53C80.


As for dead boards for parts, maybe a new section on the forum is needed for "Part Sales & Collection".

We do have a trading post you can use.

 

[YMK]

Try some normal vs blind SCSI benchmarks. The latter will remove REQ/ACK handshaking from the equation.