There are also sweet dumplings: every day, and the business hours are during the day.
National Security Temple: Weekends are basically during the day.
Pan Jiayuan: Books are cheaper here, and more people go there in the morning. You can buy good books early.
Maple Leaf Red Market: You can also visit Shijingshan when you have time.
Haidian Book City: Every day.
The hardware must be in Zhongguancun Hailong, Dinghao and so on.
But the software is also sold in it, just don't know if it is the biggest.
There is also a software store on the first floor of Dinghao, and some counters also sell software.
But those are mostly pirated.
References:
/zhi nan/20080 1 12- 1205 . html