68030 @ 16MHz vs. 68000 @ 16Mhz: how much faster?

[Trash80toHP_Mini]

Just what the title says, I'm wondering about the performance differential between 68030 and 68000 running at the same 16MHz clock. Any notion or point in the right direction to find out? My hunch is that it would be significantly faster, if not amazingly faster which I doubt.

 

[Dog Cow]

Depends on the workload of course. The 030 has a full 32-bit data bus so it can put an entire long-word on the bus at once, whereas the original 68K only has 16-bit data bus. The 030 has instruction caching too.

 

[dcr]

Was there a 16 MHz 68000?  I see several Macs used a 8 MHz 68000 but haven't found one at 16 MHz.

The LC had a 16 MHz 68020 and the LC II had a 16 MHz 68030.

 

[dcr]

Never mind.  Motorola did make a 16 MHz 68000.  Can't find a Mac that used it though.

 

[Dog Cow]

Never mind.  Motorola did make a 16 MHz 68000.  Can't find a Mac that used it though.

Portable.

 

[Gorgonops]

Portable.

And the Powerbook 100.

 

[Trash80toHP_Mini]

Portable is the target machine, so the bus remains 8bit. MicroMac Performer looks like a relatiively easy path to a bit of acceleration and jailbreak into 68000 hostile code base for the Portable. Wondering what performance gain might be at same clock?

 

[demik]

Difficult to estimate.

68000 to 68020 is about 1.6 more IPC (benchmarks done by Motorola on CPU32 vs 68000. CPU32 is a basically 68020 core with only 68010 instructions and a 68000 like bus (16 bit wide)).

68020 to 68030 is mostly dependant on

- how the software make use of the CPU cache

- how many new instruction it uses (memory access, compute)

Out of my A** I guess 2.0 more IPC

 

[Gorgonops]

Portable is the target machine, so the bus remains 8bit.

The Portable has a 16 bit wide bus.

 

[dcr]

Portable.

Ah.  My bad for only looking through desktop machines.

 

[Fizzbinn]

Maybe compare a Macintosh Classic II (68030 16Mhz) to a Macintosh Portable (68000 16Mhz) via old benchmarks:

https://lowendmac.com/2000/mac-classic-ii-benchmarks/

cache CPU graphics disk math
32 KB 4.00 3.49 2.30 5.60
64 KB 4.00 3.45 2.30 5.43
128 KB 4.01 3.49 2.26 5.54
256 KB 4.01 3.49 1.91 5.42


vs.

https://lowendmac.com/1998/mac-portable-benchmarks/

cache CPU graphics disk math
32 KB 2.15 1.82 1.25 1.95
64 KB 2.15 1.82 1.23 1.95
128 KB 2.15 1.82 1.24 1.95
256 KB 2.15 1.82 1.24 1.94




CPU almost twice as fast on the '030.  There are a bunch of other old Macs you could look at the Speedometer 3.06 results for on that site for caparison.

 

[johnklos]

All these factors contribute:

• Bus width. 16 bits versus 32 bits, except for LC / LC II and similar models
  
• Memory clocking. m68000 takes four cycles. '020 and '030 take three.
  
• ALU. m68000 has 16 bit ALU and '020 / '030 have 32 bit ALU
  
• Instruction cache of 256 bytes on the '020 and '030. m68000 has none.
  
• Data cache of 256 bytes on the '030. Both caches make a big difference, particularly on a 16 bit data bus.
  
• Instruction timing. Lots of instructions take less clocks on '020 and '030 than m68000.
  

I'd generally expect a 16 MHz m68020 or m68030 to be generally twice as fast or more than a 16 MHz m68000.

 

[Franklinstein]

Maybe compare a Macintosh Classic II (68030 16Mhz) to a Macintosh Portable (68000 16Mhz) via old benchmarks:

It's a good idea to compare to 16-bit buses such as the LC II, Color Classic, and Classic II. This helps temper expectations but also illustrates the vastly increased performance of the '030 core over the '000, which is significant.

The 68000, though a pretty well obsolete core by '89, was used in the Portable and PB 100 in CMOS form (as the 68HC000, probably for "High Cost") because it was extremely power efficient and, in at least the PB 100, an extremely tiny chip. I don't believe the '030 was ever made in a CMOS process except perhaps as an EC variant (no MMU), which should be fine for Portable use but would preclude your use of VM. If you plan to build a Portable accelerator with a full '030 your battery life will likely be noticeably impacted.

 

[Gorgonops]

I don't believe the '030 was ever made in a CMOS process except perhaps as an EC variant (no MMU)

According to the datasheet the '030 was fabricated in the same HCMOS process as the 68HC000. Apparently the 68020 is as well. The difference in max power draw between the 68HC000 and the 68030 is still about an order of magnitude; the datasheet says it's .26 watt at 16.67mhz for the 'HC000 while the '030 manual says it can dissipate up to 2.6 watts, doesn't say what speed that applies to; presumably 40mhz, that's the highest rating in the datasheet I'm looking at.

Interestingly enough this *does* mean that an '030 doesn't draw a lot more power than an original HMOS 68000.

 

[Franklinstein]

That's probably what the "HC" in 68HC000 stands for, is HCMOS. High Cost is probably also accurate though. They seem to have split the datasheets for the '030 and 'EC030, which is probably the source of my inaccuracy. After further reading of the apparently EC-specific data sheet, it appears the EC variant dissipates the same 2.6W at 40MHz, so there's likely not much to be gained there by using it rather than a full '030.

 

[Trash80toHP_Mini]

Portable is the target machine, so the bus remains 8bit.

The Portable has a 16 bit wide bus.

DuOh! My bad there. Can't forget the 4-5 GALs in terms of power budget. Haven't looked into compatibility yet, but Freescale is still turning out 68030 for embedded applications. Hoping to end up with a very modern process 68030 and the GALs lumped into a single more modern component that takes less power. Could have voltage problems, dunno. The embedded procs aren't same/full featured, but there's no need of MMU in this application.

Very early research into possibilities here. But Performer looks like the best approach to getting something faster into the Luggable. I've still not finished buzzing the board out. Started that a couple of very rough years ago, ready to look further into it finally.

Original Thread six pages of jibberish, If some research comes together I'll post a new one and get going again.

 

[Trash80toHP_Mini]

The 40MHz dissipation figures would be lessened by approximately what percentage with the CPU throttled down to 16MHz?

 

[Gorgonops]

High Cost is probably also accurate though

Did it actually cost more? The fact that it appeared in a singularly expensive machine isn't really evidence one way or the other, plenty of ridiculously expensive computers had maybe a $100 bucks worth of silicon inside. "High Speed" CMOS was invented in the late 1970's and started spreading in the early 80's, when the Mac Portable came out there was nothing special about it.

(The main reason for the Portable being *actually* more expensive wasn't CMOS, it was that it used static RAM. Static RAM requires 4-6x the transistors than the same quantity of dynamic RAM. Oddly enough that *still* does save power because it only really consumes power when the contents of those transistors is changing instead of constantly having to cycle.)

The 68000 itself was a pretty darn expensive chip when it came out, it's one of the reasons why IBM didn't plunk it into the 5150 and we don't live in whatever alternative universe that would have spawned.

 

[Franklinstein]

If HCMOS existed in the mid-70s and there was no price difference, why wouldn't they have used it to begin with? Some brief internet sleuthing suggests the original HMOS 68000 was $487 when introduced in 1979, while the HCMOS 68HC000 version was about $800 at introduction in 1985.

I'm aware of the Portable's development history. Close to half of the original M5120's $6500 price was down to the Gassee-demanded active-matrix LCD panel. The SRAMs were the next most expensive components, which is why they were dropped for PSRAM in the M5126.