0) About Black Arrow
1) The concept
2) Specifications
3) Gallery
4) Configuration
5) Underclocking
6) Creative secondary uses
7) Veredict
0) About Black Arrow I think any analysis of a product of BA should start with some words about the company. BA announced by the end of 2013 their new Minion chips, with a revolutionary (at that time) efficiency of 0.7W/GHs. 2 Miners were announced, the X-1 and the X-3, opening preorders by September of that year and promising delivering them no late than February 2014. What came before filled tons of threads and legal actions. No unit was shipped on time: the luckiest ones received them on October, many other never received them, promises of compensation with cloud mining where false, refunds never arrived… Moreover, the X-3 had design defects both in the PSU and the mainboard (unnecessary capacitators that were not removed for the final design, as confesed by BA in their forum) that provoked failures and fires. New people not familiar with the story of this company should read threads of the affected (as
https://bitcointalk.org/index.php?topic=774278.0) if they are considering buying any product of the company, especially as they have launched a new product, a hardware wallet.
The personal recommendation of who writes this is not buying in any case any product directly from this company. However, these days we can see many used X-1 and X-1.5 units on sale on eBay under $120, and I write this Guide+Review for those interested on buying it, as I think it has many advantages for newbies interested in start mining.
In spite I empathize completely with those affected by the company, I would like to strongly request them
not to post here if it is for criticizing the company, as this thread is for helping those who have acquired a used unit. Of course, Black Arrow is not welcome to post here if it is not exclusively for contributing with technical info.
1) The concept BA included their Minion chips in two completely different miners: 1) The server-oriented, big, heavy and noisy X-3, with 1 Th/s of mining power (as far as I know I think there is a revision with 2 Th/s), 2) The home-oriented, tiny and friendly X-1 (and its revision, the X-1.5) with 100 Gh/s (150Gh/s in the miner we talk about today). Both were conceived as totally stand-alone units: including an internal PSU, a control board, and a touch screen for configuring them. Just plug and mine. Have BA launched these miners on time, they would have probably became the reference for all the industry and BA a leader company.
The X-1.5 is a miner oriented to those who want a small, quiet and easy to operate miner. You don’t need to acquire a PSU (power supply unit) as with the big majority of the miners in market. Neither you need a control board, or a computer or a Raspberry Pi, everything is inside this box not much bigger than a computers ATX. You don’t even need a computer for the initial setup! You can do this on its touch screen. It comes with a WiFi antenna, so you can place it virtually on any place of your home. It is so discreet that probably no visits will ask you about it, so you will not feel as having a marijuana plantation at home.
2) Specifications Dimensions: 8cm x 21cm x 23cm (3.15in x 8.27in x 9in)
Weight: 2.1kg
Chip architecture: “The Minion”, with 28nm architecture
Hashing power: 150 Gh/s at default speed (100 Gh/s in the case of the X-1). It can be overclocked to 180 Gh/s
Power efficiency: BA claims 0.75 W/GHs. However, this is for the chip only. Considering the board, the fan, and loses of the PSU, in my hands they work at 135-140 Watts “at the wall” (measured with a watt-meter), meaning an efficiency of about 0.91 W/GHs. However, as I’ll show later we can underclock it up to 0.72, much more acceptable nowadays
Cooling: A titanic single 20cm fan from Cooling Master at the right side. Extremely quiet. Miner is not designed to be stacked to allow airflow. However, if underclocked, I would say you can stack 3 without problems
Control board: Rockchip motherboard running an Android 4.4.2. The SO is controlled thanks to a 4 inches display (not very responsive, I have to say). Older X-1 versions does not include the display, and uses an integrated Raspberry Pi model B instead. Miner software is cgminer.
PSU: A customized PSU that BA claims have an efficiency of 92%. The connector is proprietary, so it can’t be replaced by a conventional PSU. Uses a 3-pronged power cable, “mickey mouse” style.
Connections: 1x Ethernet port, 1x WiFi antenna, 3x USB (1 front, 2 rear), microSD port (for use with Android and also for reflashing the unit). The X-1 does not include the WiFi capabilities.
3) Gallery 
4) Configuration 1- Plug the power cord
2- Choose your mining pool (on screen or using a web interface)
3- Become rich!!!! (well, actually not…)
As simple as this!! Once powered on, the Android will launch Chrome browser on the screen and showing the stats of the miner. Temperature will be shown only as increments of 20ºC (if other number is shown, it is the average of the Prosperos on your rig). Pressing “Pool” will take you to a simple screen in which you configure your main pool and 2 backups. “>” and then “Device” takes you to clocking settings.
The 3 buttons in the bottom allows you to navigate through the Android system. You can install and use any android app (yes, you can install Office or Angry Birds). The Blackarrow app in the main screen takes you back to the miner info page, while Settings will let you configure things as the WiFi network.
Alternatively, you can use other computer. Open a web browser and type the IP address that the miner page of your unit shows. For example
http://192.168.0.5
User name: user
Password: blackarrow
Yubikey: don’t type anything
The interface is completely different from the one of the miners, but you can see detailed statistics and configure mostly the same things.
Just one important note: NEVER UPDATE THE MINER TO v1.18, as the interface suggests. Several users have reported instabilities or even bricked miners. That update was prepared for the X-3, and not optimized for its small brothers. I suggest you versions 1.16, 1.17 or whichever your miner includes by default. More info in the Black Arrow forum:
http://ecointalk.net/ 5) Underclocking These instructions are not my merit, but the merit of the people in BA forums, I’m just compiling them. Thanks to them. The easiest way is go to the “Device” page from the miner info page, and set a voltage form the list below, but I discovered that several times the miner will resist it and go back to default settings. So I recommend you go the hard way: by SSH using a terminal (you know, that black screens with white text you see in films about hackers). Don’t worry, it is actually very easy and I’ll guide you step by step:
1 – Download and unzip the Putty software:
http://www.putty.org/2- Open it. Write your miner’s IP addres (remember, it is on your miner’s screen) and click Open
3- When it requests a user, type: ba (and press enter, of course)
4- When it requests a password, type: ba (and enter)
5- Congrats, you have hacked it and you are now the superuser!! Now let’s go to the appropriate folder, type: cd /home/ba/bamc (and hit enter)
6- Let’s see what is inside, type: ls –al (enter)
7a- Newer versions of the firmware will include the file “bamc.conf”. Type: nano bamc.conf
8a- Go to the line Voltage (with the arrow keys of your keyboard) and change it with one of the values of the table below. Pres Ctrl+X, press “y” to overwrite the file. Unplug your miner and plug it in again
7b- Older versions. Type: cgminer.sh. Localize the line “power_manager 80” and change the “80” with the hexadecimal code of the voltage you want (see table below). Crtl+X to exit, save it and unplug the miner.
Once done, the miner will restart several times the cgminer until it finds an appropriate clocking frequency. In my hands, the trick is to find the minimum voltage that drives to a Frequency of 500 Hz, or the next superior voltage value if it is a bit unstable (many errors mining). I recommend you to test several, using a watt-metter to assess your real efficiency. In my hands, in general a Voltage of 0.6625 drives 100 Gh/s at 72 watts with only a 0.1% of errors (better than default settings). But this optimal voltage can be different depending on the particular miner. This is the table of accepted voltages and the corresponding hexadecimal code:
0.85000 7A
0.84375 7B
0.83750 7C
0.83125 7D
0.82500 7E
0.81875 7F
0.81250 80
0.80625 81
0.80000 82
0.79375 83
0.78750 84
0.78125 85
0.77500 86
0.76875 87
0.76250 88
0.75625 89
0.75000 8A
0.74375 8B
0.73750 8C
0.73125 8D
0.72500 8E
0.71875 8F
0.71250 90
0.70625 91
0.70000 92
0.69375 93
0.68750 94
0.68125 95
0.67500 96
0.66875 97
0.66250 98
0.65625 99
0.65000 9A
0.64375 9B
0.63750 9C
0.63125 9D
0.62500 9E
6) Creative secondary uses Many times we complain about the fact that ASICs are machines that can’t be used for any other purpose than mining, with the exception of heating your home. Well, I would say the Prospero X-1/1.5 is the first miner with further uses once it’s life as miner has ended. You just need imagination:
- Android computer. You have a whole Android thing with a 4-inch display. Flash it, root it, play with it. I don’t know much about android or modding, but if you can install a linux on it, I can imagine serveral uses: storage server if you connect an HDD? Set-top-box using Miracast? The first version of of the X-1 came with a Raspberry Pi model B instead of the android thing, so you can use it for even more things!
- USB power supply. It has 3 USB! Three! You can charge your phone, your girlfriend’s phone and your tablet at the same time, while you admire those fancy green and blue lights :-D
- Mining board for USB miners? It has USBs. It is a linux machine, after all. It is running cgminer. I haven’t tested it, but theory says it should work as a control board for other miners! An rPi costs $30, and this thing about $120, ok, but you have in the same package a display (a modder for sure will be able to do incredible things), WiFi connectivity and 150 extra GH/s for your rig!!! A nice deal, I would say.
7) Veredict This miner belongs to a past generation, and the current generation (Avalon 4.1, Antminer S5, SP20-30-35) reach speeds much higher and efficiencies under 0.55 W/Ghs. This miner nowadays is not profitable: Even people not paying the electricity would need more than one year to return their investment.
In the current scene of more and more centralized bitcoin mining, manufacturers only develop miners for big data centers and farms, where cooling and noise is not a problem. But what about home miners and hobbyists, who usually can’t host a noisy a hot machine. What about those who want to mine but don’t want to have a mess of cables on a table from the PSU to the miner, those who doesn’t know nothing about mining, but only want something small over a shelf? The exception is the Avalon 4.1, very quiet and of a manageable size, but it is extremely costly. For beginners, the S3 is usually recommended due to its reduced price and noise, but the buyer needs to acquire a PSU, and some people don’t like to have a mess of cables looking as if they were going to ignite at any moment.
They may be producing a ridiculous amount of Bitcoin at the moment (about 0.0015/day today, April 2015) but the current price of used units makes the Prospero X-1.5 a good option for beginners. Miner, PSU, cooling and controller, all inside a small black metaled brick, equipped with interesting extras as WiFi connectivity and a touch screen to make it completely stand-alone. Those who pay moderately high electricity can underclock it under 0.75 W/Ghs, thus at least paying its electricity consumption. Extremely quiet (I run 3 on my small NYC apartment) and producing barely appreciable heat.
Ready to mine without any knowledge about efficiencies of PSUs, modding, rPIs, flashed SD cards, linux or different mining software. Just plug it in, choose your pool, and forget it.
