Archive for the 'Urn' Category

Sometimes Mac break

Yeaterday I booted old Catalina DP on MY NMP, it showed update – DP beta 11.
I thought, ok, lets see.

Update got downloaded… reboot…. firmware update… reboot… mac is dead.

Mac doesn’t boot anymore.
It just starts up, no bootchime (and I have it disabled anyway), after like 5 mins it lights up connected display, displaying black screen on it (even tho at proper resolution)

That’s it, no boot, wait many hours, nothing changes.

PRAM reset – didn’t help. SMC reset – didn’t help..

A secret way to do pram reset – didn’t help. (take out cmos battery, it clears RTC, mac will boot in “EFI_BOOT_WITH_DEFAULT_PARAMETERS” mode next time, ignoring NVRAM on startup, at least in PEI mode)

Cool update I thought. At least I can swap ssd to macmini and get my data back.

The final solution was to get access to eeprom, it’s on bottom pcb, inside NMP.

Using CH341A/AsProgrammer (thanks Alex for CH341A), I was able to read and write the EEPROM chip with main bios rom.

I tried to make pram reset in hard way, wiping out content of two VSS partitions inside efi ( they hold nvram arguments).
That helped, mac booted.

Appearently it’s a bug in new fw of parsing some nvram params.

Apple, Wanna that firmware ? I still have that dump.

P.S. this is how mac looked for few days, still can boot it this way. bios rom IC is on the other side of pcb you can see.


New MacPro, many thunderbolts and Video Cards

Lots of people ask what will happen if they connect videocard over thunderbolt 2 to new MacPro.

Let’s figure that out.

First, what is thunderbolt 2.

In thunderbolt 1, you had 2 lines of bidirectional 10 Gbit/s link, one for video and one for data.

In thunderbolt 2, these lines are combined, now you can get either 20 Gbit/s for data or for video.

That gives us 2.5 Gbyte/s.

now lets looks at pcie


PCIe Bandwidth Comparison (Each Direction)
PCIe 1.x PCIe 2.x PCIe 3.0
x1 250MB/sec 500MB/sec 1GB/sec
x2 500MB/sec 1GB/sec 2GB/sec
x4 1GB/sec 2GB/sec 4GB/sec
x8 2GB/sec 4GB/sec 8GB/sec
x16 4GB/sec 8GB/sec 16GB/sec

so, TB2 is a bit faster than pcie 3.0 x2 or pcie 2.0 x4 (talking about pcie 2.0 because true (old) macpros has pcie 2.0 links)

Now, if you want to know performance impact, open this link for a good article at anadtech and look for red bar.

In games, performance impact could be from few percents up to 40 percents. In opencl workload impact gonna be high.

Let’s look at new macpro

Let’s look at new macpro, thanks The Verge and Apple for pics of it.

1) The processor and RAM. There is only one CPU, and 4 ram slots around it, ram seems to be easily accessible.

Mac Pro processor

2013 06 10macprofirstlook 1 verge super wide

2) The disk. Their so called pci-e ssd is…. looks like some macbookpro ssd.

2013 06 10macprofirstlook 8 verge super wide

3) The GPU. There is two of them, you can see their backplates on sides of MacMiniPro

apple wwdc mac pro innards png

2013 06 10macprofirstlook 2 verge super wide

These things don’t look changeable.

Hence you will be able to upgrade memory and disk, but nothing else, sounds like mac mini.