mijobooks Chapter 448 Star Core Chip Test
Chapter 448 Star Core Chip Test
The chips were shipped back from Singapore. Liang Mengsong personally escorted the shipment, flying from Changi Airport to Hong Kong, and then transferring to Jinan. He never let the aluminum alloy suitcase out of his sight the entire way.
When he went through security, the officer asked him to open his suitcase. He opened it, but kept his eyes fixed on the officer's hand, as if afraid that the gloved hand would touch the chip packaging. The officer probably felt uncomfortable being stared at, so he just glanced at it and told him to close it.
When they arrived at the R&D center, it was already 3 p.m. Li Mo and the three members of the testing team were waiting in the laboratory. An anti-static mat was laid out on the table, the test board was already connected with ribbon cables, and the oscilloscope probe had been calibrated twice.
The lab's air conditioning was set five degrees lower than usual. Some people put on a jacket, while others didn't have time to put one on and got goosebumps on their arms.
Liang Mengsong placed the box on the table, opened it, and inside was a black foam pad with ten chips embedded in it, each individually sealed in an anti-static bag.
He took one of them out and placed it on the tray next to the test board. The chip, about the size of a fingernail, had a dull metallic sheen under the fluorescent light, and was etched with the Spark logo and a series of numbers.
"Did everything go smoothly along the way?" Li Mo asked.
"I held this box the whole time on the plane," Liang Mengsong said. "The flight attendant asked me what was inside, and I said it was an artificial pacemaker. She immediately stopped touching it."
Li Mo chuckled; he found Liang Mengsong, this engineering student, to be quite humorous. He put on his anti-static wrist strap, picked up the chip with tweezers, aligned it with the packaging slot on the test board, and slowly lowered it.
The instant the chip's pins aligned with the slot, he gently pressed down with his wrist, and the chip clicked into place. The sound was soft, but everyone in the lab heard it.
"Power it on," Li Mo said.
The engineer, seated in front of the oscilloscope, pressed the power switch. The indicator light on the test board flashed green. Then the display lit up.
The screen was blue at first, then a line of white English text appeared: StarCore Booting… The cursor blinked three times at the end of the sentence, and then the screen changed—the StarCore OS logo popped up, with a progress bar below it. The progress bar jumped from zero to one hundred percent in less than a second. The desktop appeared, still with that dark blue background, and a few icons were quietly arranged along the edge of the screen.
"Startup successful."
The speaker was a young engineer sitting at the very edge, his voice low, as if afraid of waking something. But then the entire lab erupted—someone took off their glasses, wiped them, and put them back on; someone slapped their thigh; someone braced themselves on the edge of the table, their shoulders slumping as if they had let out a huge sigh.
Li Mo neither shouted nor moved, but the hand holding the tweezers was trembling slightly. The tips of the tweezers touched the metal tray, making a very fine and fragmented tinkling sound. He quickly put the tweezers down and pressed them with his fingers.
"Let's run a baseline test first," he said.
The benchmark test program was written in advance and ran a test of CPU integer arithmetic, floating-point arithmetic, and memory read/write bandwidth.
As the data scrolled across the screen, the person responsible for recording followed the numbers down with their finger, muttering to themselves—"400MHz clock speed stable without fluctuations, integer operations exceeded design expectations by 3%, floating-point performance was slightly low, less than two points lower, and memory bandwidth met the requirements."
Li Mo leaned over and glanced at it, then said to run it again. The data from the second run was exactly the same as the first.
"GPU testing," Liang Mengsong said, arms crossed, "let's run those two scenes first. Those were the scenes that caused the screen tearing during the last simulation."
Li Mo nodded and entered the test command himself. The screen switched from the desktop to a 3D rendered scene—a rotating sphere composed of thousands of triangles with a metallic texture on its surface.
The sphere spun once, and the screen remained clear. During its second rotation, a tiny flash appeared in the lower right corner of the screen, fleeting like a silent lightning bolt striking the distant horizon on a summer evening.
Li Mo's expression didn't change, but he quickly drew a coordinate on his notebook, marking the location where the flashing appeared.
The second scene is a particle system simulating rain, with thousands of particles falling simultaneously from the top of the screen. When the particles are halfway down, a few suddenly turn into long purple streaks, flashing on the screen for a fraction of a second before returning to normal. Only a few.
"It's still those two scenarios," Li Mo wrote the last line in his notebook, then put down his pen. "The GPU screen flickering only occurs under these two specific rendering conditions, and the location perfectly matches the simulation results. It's not a random fault; it's a problem with the underlying algorithm at the design level—the graphics accelerator's z-buffer algorithm has a bug in particle depth sorting. What about power consumption?"
The person in charge of recording the data flipped the entire test report forward one page, stopping their finger on the lower middle section.
The full-load power consumption is 608 milliwatts, which is 15% higher than the design value, and the standby power consumption is 72 milliwatts. The USB high-load packet loss rate is 0.7%, which is just on the edge of the design limit.
As the numbers jumped up, he glanced at Li Mo and saw that Li Mo was smiling—not a hearty laugh, but a slight upturn of the corners of his mouth that he quickly stopped, as if he had seen something expected or even anticipated. Then he lowered his head and continued writing his notes, the pen tip scraping a deep ink mark on the paper.
"What about the yield rate?" Ling Yun's voice came from the doorway.
Everyone in the lab turned around. Ling Yun had entered at some point and was standing in the doorway, his shoulder resting against the right side of the door frame.
He was wearing a dark blue work jacket, zipped up to his chest, with a small patch of chalk dust on his left shoulder, as if he had just left the conference room covered with blueprints.
Liang Mengsong turned around, picked up the test report that had been marked several times with a marker, and flipped to the last page. "The first batch of ten test chips, all ten can start. Two of them exceed the power consumption limit, one USB interface has intermittent packet loss in high-speed mode, and one GPU has screen flickering with a frequency higher than the design standard, but all chips can run the full benchmark test - the first batch yield is 86%."
After saying that, he paused for a moment. Then he looked at the test report again from beginning to end, as if to make sure he hadn't misread any of the numbers.
In fact, he could recite every line of data on the report. From the start of the renovation at the Singapore plant to the tape-out and return of the wafers, it took one year and two months. During that time, the equipment was shut down three times for debugging, and the process parameters were adjusted no less than a hundred times.
One night, the etching machine alarmed, and he and three engineers stood inside for five hours wearing protective suits. When they came out, the marks on their faces from the masks hadn't faded for three days.
Ling Yun walked in from the doorway, picked up the chip that hadn't yet been put back in its anti-static bag, and examined it under the light. He twirled the chip slightly between his fingers, causing the metal casing to reflect a glimmer of light amidst the darkness.
"This is the first chip to go through the entire process from design to tape-out to testing," he said, putting the chip back in the tray. "No matter how many problems it has now, it at least proves that we can do it."
Li Mo removed the anti-static wrist strap and placed it on the table. "Looking back at the problem, the GPU screen flickering is at the algorithm level, requiring modifications to the z-cache sorting logic, focusing on the rendering pipeline. Power consumption is 15% higher; our original four-level voltage domain division was too conservative, we need to increase it to six levels, and with optimizations to the clock gating, we can further reduce it. USB packet loss is easy to handle; it's a timing configuration issue with the controller registers, and the patch will be available this week."
"Can a second edition be released before the end of the year?"
"Yes," Li Mo said, already pulling the keyboard over to start writing the debug plan. "Give me two months, and I'll clear up all the problems."
Ling Yun didn't say anything more. He walked around the test bench, looked at the running chip test interface, looked at the still-fluctuating waveform on the oscilloscope, and looked at the engineers huddled in front of the monitor reviewing the test report—one had hair that looked like a bird's nest, one had one sleeve of his jacket rolled up, and one was holding a piece of cold pie in his hand, taking a bite but forgetting to chew it because his eyes were fixed on the screen.
He stopped after walking around, stood behind the engineer whose hair was as messy as a bird's nest, glanced at the screen, and said, "I'll ask the cafeteria to add more dishes for tonight's overtime meal."
Then he walked towards the door. Liang Mengsong followed him out a couple of steps. Ling Yun turned to him and asked, "What's the current monthly production capacity in Singapore?"
"Twelve thousand wafers, if the equipment runs at full speed. But if the second version's tape-out window is stuck in December, we need to coordinate with the Shenzhen factory. They have a test line that can be used—" "The scheduling authority is yours," Ling Yun said. "No need for approval. Just schedule it directly."
Liang Mengsong didn't say thank you. He stood there, watching Ling Yun walk out of the lab, then turned back, rolled up his sleeves, clapped his hands at the engineers still staring at the screen, and said, "You all heard that, right? We'll have extra food tonight, eat and keep working."