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taper
Registered: Dec 2001
Posts: 119 |
Event id #2391 : The 2015 REU Compo
Welcome to the 2015 REU Compo --- Hosted by LFT, Ruk and Taper!
See the event-page on: The 2015 REU Compo
Your mission is to create the most awesome one-file demo that runs on a standard C64 with a 512 kB REU and no disk drive.
Background
==========
The Commodore RAM Expansion Unit (REU) is a cartridge that provides secondary storage to the C64. It was introduced at CES in 1985. The memory in the REU cannot be accessed directly from the CPU (hence
"secondary"). Instead, the CPU must instruct the REU to transfer a given amount of data to or from the cartridge. The REU then takes over the bus, stalling the CPU, and transfers one byte per cycle.
This is basically all there is to it. Apart from the extra storage, the REU does not make the C64 faster or more powerful---although see below for some intriguing possibilities.
The largest REU available from Commodore (the 1750) was equipped with 512 kB of RAM. Nowadays, it is possible to emulate REUs with as much as 16 MB, e.g. using VICE or the 1541 Ultimate. Even though you can only use 512 kB in this competition, there should be no problems using
the RAM expansion features in the 1541U/1541U-II, Chameleon64 or any other device fully compatible with the Commodore 1750 REU.
Rules
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1. Your entry must be in .PRG format with a BASIC header. The file must load to address $801, and end before it reaches the I/O area at $d000. The gives a maximum file size of 51201 bytes.
2. You may assume that a REU of at least 512 kB is available.
3. Your entry must work with a larger REU (i.e. you cannot assume that the upper address bits are ignored). You may not use the extra RAM available in such configurations.
4. You cannot make any assumptions about the initial contents of REU memory.
5. Your entry must work on a real C64 with a real 512 kB REU from Commodore. Please keep in mind that there could still be bugs in the emulators.
6. Deadline is set to 2015-12-31 at 23:59 in a time zone of your choice. Your contribution needs to be mailed to reu@wuff.se to be accepted. You are free to create a CSDb entry for your contribution, else we will do it for you.
7. Immediately following the deadline, voting will take place on CSDb during a period of two weeks. Anonymous votes will be counted. We allow self-voting unless you have multiple personalities.
Suggestions
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For your inspiration, here are some ways in which a C64 demo might benefit from an REU:
Obviously, the extra RAM is useful. For instance, the demo might pre-compute large amounts of sprite graphics, and then quickly retrieve a subset of the data just before it's needed.
The fast transfer rate could be used to speed up scrolling operations: You can copy a large bitmap from the C64 to the REU, and then back again at a slightly different address.
Last but not least, the REU has a mode where every byte in a transfer gets written to the same destination address. This can be used to display graphics using the idle byte, for instance. The target address
could also be an I/O register, and this might enable some new VIC tricks.
Technical information
=====================
Please refer to the following documents for details about the REU programming interface:
http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/progr..
http://codebase64.org/doku.php?id=base:reu_registers
Happy hacking!
/LFT, Ruk & Taper |
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Oswald
Registered: Apr 2002
Posts: 5095 |
more than enough to animate koala at 50fps |
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Smasher
Registered: Feb 2003
Posts: 521 |
thanks guys for the answers! |
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Smasher
Registered: Feb 2003
Posts: 521 |
if this wasn't posted before... REU-Colors
it's of course no crest or hoaxers megacool REU demo, but it contains the source with comments, so now it's quite clear to me how to store data in reu banks and how to move them back to c64 ram.
for those who are at my level, i.e. moving the first steps in the REU world, I think it will help. |
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Firehawk
Registered: Aug 2011
Posts: 31 |
If this would help or inspire, the entire FRONTIER source is found here (although comments are lacking).
Frontier |
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Smasher
Registered: Feb 2003
Posts: 521 |
uff Firehawk... I had a look at your source files and now I feel like I'm still in the kindergarten of coding school again :)
congratz! and greetz from ze spaghetti coder #1 :) |
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lft
Registered: Jul 2007
Posts: 369 |
Just a friendly reminder to get your releases in shape for the compo. Deadline is 2015-12-31 at 23:59 in a time zone of your choice. Happy hacking! |
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Count Zero
Registered: Jan 2003
Posts: 1940 |
I volunteer for testing - promising not to pass any bits of data or information to anywhere. Can't - wait - for - stuff - here ...
Will test on my extra buggy "Sorex-REU" (CMD 2MB clone) with RAM initalisation bug as well as on a 1541U1 with 1.72 firmware - in case you wonder :) |
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Dane
Registered: May 2002
Posts: 423 |
Quote: Just a friendly reminder to get your releases in shape for the compo. Deadline is 2015-12-31 at 23:59 in a time zone of your choice. Happy hacking!
Christmas holidays are saved...cause we're still short on gfx. :) |
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ChristopherJam
Registered: Aug 2004
Posts: 1409 |
Still coding. Two effects down, "just" need music, effect sequencing, a logo, a better sidebar image and a start screen.
Doesn't help that my music player's in pieces on the floor at the moment; might be submitting in Samoa Standard Time at this rateĀ
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Dane
Registered: May 2002
Posts: 423 |
PM if you need music, Christopher. :) |
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