Centris 650 surprise

[pcamen]

A while back I was thinking that perhaps having an 040 Mac was better than an 030 one with an 040 accelerator, like a IIci with a Daystar 040.  My thinking was that a native 040 model might be more compatible with software, nothing substantiated, just a theory.

So I pondered all the 040 models out there to figure out what to get.

I already have a 700, but that's at 25Mhz and I thought I could do better.  The 840AV is the speed king in the class, but those are expensive, and brittle.  To make a long story short, I figured that having a Quadra 650 was a nice compromise at 33Mhz.

So I purchased one on eBay, and when it arrived, I realized I didn't pay close enough attention and it was a Centris 650, which has the LC 040 and only at 25Mhz.  Doh!

So I purchased another one and it came non-functional and damaged.  Double doh!

Anyways, @jeremywork was over yesterday and was looking at my Centris 650, and noticed that it had an AAUI ethernet connector on the back - The Centris 650 didn't come with that.  Hmm.  We we popped the heat sink off the processor and sure enough, it was a full 040.  Well what do you know, it was upgraded with a Quadra 650 board. 

So I guess  I have my Quadra 650 after all, with another for backup parts. 

 

[MOS8_030]

The Quadra 650 was the solid workhorse of the 040 Macs.

 

[Cory5412]

Nice Find! It seems like case/badge swaps were common on these. 

The 840AV is the speed king in the class

I would like to do some benchmarks at some point, because the 950, 800-650, and 840 each have different go-fast tricks and might be suitable in different scenarios. The 800 (and I believe 650 should) can use interleaved RAM, and the 840 doesn't. The 950 of course has a higher RAM capacity and more expansion bays and slots.

That's also before 040 upgrades and accelerators. I've got a friend with a 650 that's been upgraded and chipped and it's running at like 45 or so MHz. He does some Apple II dev stuff that if i remember correctly doesn't work on PowerPC, so that uplift is nice.

 

[jeremywork]

As far as I've been able to discern, please correct anything wrong:

Quadra 700-900 introduce the line with 25MHz 040, 80ns memory, solid 24-bit frame buffer

Quadra 950 is essentially a 33MHz speedbump of the 900, with some logic improvement

Quadra 800/650 add 60ns interleaving memory, improve video speed by removing a wait-state, but remove 24-bit color

Quadra 840AV bumps the speed to 40MHz, receives (this is hazy) full Nubus 90 support for I believe the first time, re-adds 24-bit color, and high speed GeoPorts. It also has SCSI manager 4.3 in ROM for better high speed SCSI support, but the onboard DSP does occupy the PDS header, so an 040 and one DSP is all you get (and obviously only 3 Nubus slots are present.) 60ns interleaving RAM looks to be retained; can't find something that says otherwise.

I would also love to confirm the speed differences with live benchmarks, but these Radius VideoVision benchmarks suggest the 840AV was the fastest Nubus mac on the chart in terms of raw bus performance, outperforming even the later PowerPC Nubus Macs.

http://archive.retro.co.za/mirrors/68000/www.vintagemacworld.com/radius/vvision.html

http://mirror.macintosharchive.org/max1zzz.co.uk/++Uploads [UL]/Barracuda/radius.vintagebox.de/RadiusQA/Telecast.html

 

[superjer2000]

Only the base model Centris 650 had the LC and no Ethernet. You probably don't have a swapped motherboard system, but just not the base model.  I also have a Centris 650 with the full 040 and Ethernet.  The different configurations are discussed in Macworld April 1993.  You can tell if you have a 25mhz or 33mhz unit.

 

[jeremywork]

Only the base model Centris 650 had the LC and no Ethernet. You probably don't have a swapped motherboard system, but just not the base model.  I also have a Centris 650 with the full 040 and Ethernet.  The different configurations are discussed in Macworld April 1993.  You can tell if you have a 25mhz or 33mhz unit.

Interesting! I had not known this- @pcamen, I believe it was a 25MHz RC chip, not a 33. This would explain it perfectly.

 

[pcamen]

Well heck, I got all excited for nothing.  Popped the heat sink again and sure enough, it is a 25MHz RC version.  What is the RC version anyways?

 

[jessenator]

What is the RC version anyways?

I think RC was the full-featured version. LC lacked a coprocessor, and EC lacked n FPU and MMU.

 

[trag]

Didn't some of them have 4MB on the logic board and others had 8MB?    1993 was a long time ago....

 

[Fizzbinn]

Well heck, I got all excited for nothing.  Popped the heat sink again and sure enough, it is a 25MHz RC version.  What is the RC version anyways?

“RC” is about the physical package type of the CPU, found this page useful for decoding Motorola 68k CPU markings:
http://www.cpu-world.com/info/id/Motorola-identification.html#68020__68030__68040__68060__68881_and_68882

and this one on the evolution of the 68040 revisions (versions got smaller transistor die sizes, more more power efficient, less heat over time):

http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.m68k/2006-01/msg00000.html

which can help you figure if your ‘040 needs a heat sink, might be a good candidate for overclocking if your interested in that sort of thing. 

 

[AlpineRaven]

Love Quadra 650/800 board - solid macs they are..
Cheers

AP

 

[MacFox]

I have a Centris 650 too and I love it!

 

[beachycove]

I have a Quadra 650 here (well two, actually -- I am a packrat). It is quiet and well engineered, with PDS and 3 Nubus slots, plenty of room for RAM, and very decent video for the period.

People complain about the case for some reason, whereas the fact of the matter is that a Centris/Quadra 650 case (IIvx, P600, and 7100 too, by implication) is going to last for decades longer than other machines of the period, because so much of it is metal rather than brittle plastics. Seems a very good thing to me. Then it's said that they are ugly, but I don't see that myself; there are lovely curves on that front bezel. Have a look, for instance, at the horizontal  air vent by looking up from below for a nice design touch.

 

[pcamen]

Well some good news.  A Q650 I also got off eBay has a damaged case (in shipping) but a good MoBo.  So I can have a stealth Q650 inside a Centris 650 case. 

 

[beachycove]

The badge can be changed.

 

[pcamen]

Yea but I'll know.