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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
=====
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
===========
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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Burglar
Registered: Dec 2004
Posts: 1031 |
"no tricks", in my book that includes not adding a reu. |
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Frantic
Registered: Mar 2003
Posts: 1627 |
I suppose it refers to no tricks regarding the loading of the file? |
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ChristopherJam
Registered: Aug 2004
Posts: 1378 |
...and of course Krill's rule is already covered by the very first rule of this compo.
FWIW, in the thread linked algorithm was suggesting one-filers also require no additional hardware. Maybe we just need more explicit category names?
In any case, cool compo. I was going to pass on this one, but I'm starting to get ideas now. Stupid brain.. |
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algorithm
Registered: May 2002
Posts: 702 |
What about a Turbo Chameleon compo. The cartridge can allow its features (turbo cpu etc) to be turned off on from within the c64 side. Has there been any demonstrations specifically done to take this into account? |
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Moloch
Registered: Jan 2002
Posts: 2896 |
If anything CSDb needs less categories and credits options |
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FATFrost
Account closed
Registered: Sep 2003
Posts: 211 |
i love the turbo but it's cheaper for me to buy a laptop and run vice and get all the same features. ;) |
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chatGPZ
Registered: Dec 2001
Posts: 11116 |
After doing more tests i can tell that x64sc (NOT x64!) from VICE is actually pretty accurate for REU stuff - other emulations not so much (yet?) :=) |
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Firehawk
Registered: Aug 2011
Posts: 31 |
Yes Groepaz is correct. We had problems with Qi on the x64, it apparently has a problem with real-time streaming of data into memory (i.e. $3fff pictures and 40+ rastersplits etc). The x64sc works perfectly, the entire demo was developed under emulator and tested on 1541U2 without any glitches. |
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chatGPZ
Registered: Dec 2001
Posts: 11116 |
in x64 the timing is often wrong by one cycle, as the DMA/BA behaviour is not cycle exact. |
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Dane
Account closed
Registered: May 2002
Posts: 421 |
Good good, I'd hate for all those parts-in-progress to be done in vain. :) |
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