pouët.net

More for the record (and as a base for an overview table on sizecoding.org):
Party: @party online 2020
URL: http://atparty-demoscene.net/
Upload: http://party.wuhu.scene.org (if this doesn't work, also by email: bostondemoscene@gmail.com)
When: June 12th, 5:00pm - June 14th, 5:00pm 2020
Where: @party Discord channel
Deadline(s): Saturday June 13th at 5 PM
Compo Machines:

• PC w/ Intel Core i7-3770K (w/ DOSBox), 486 dx2/66, or an NTSC C=64
  
• old hardware (emulated) and more details here

Compo rules:
256b Intro:

• your entry for this compo must run as a single executable and any assets, libraries, or interpreters must be packed into this 256 byte executable.
  
• The default compo machines will be either a 486 Dx2/66 running a completely stripped down version of DOS, an NTSC C=64, or DOSBox on the modern compo machine.
  
• We are open to other platforms, emulators, or faster native DOS machines at the compo team’s discretion.
  
• The hardware / software platform will be listed on the slide.
  
• other sizes might be possible with enough entries (e.g. 128B, 1K)
  

DOSBox on the modern compomachine is also fine now, for the record.