CRT8040

1. About
2. How does it work?
3. Download
    3.1 Source
    3.2 Binaries
4. Convert other crt files
5. Feedback

About

I have a small collection of crt files and wanted to use them with my retro replay. Most of them can not be flashed to the rr without modification, but as I'm a lazy person I didn't want to patch every single crt. CRT8040 is a generic solution for one special cartridge type.

How does it work?

The crts I wanted to flash are mapped into the C64's mem starting at $8000. Their length is $4000 bytes. Unfortunately the rr can just map in $2000 bytes of rom at once, so the rest of the crt data will be copied into the rr ram.  A little reset routine will do this job. It is implemented as a header which can prepended to the data section of the crt file. Please take a look at the source for more details.

Download

Source

You will need DreamAss to assemble the source. Get it here.
The Makefiles heavily depend on Unix console tools like 'dd', they will definitely not work with Windows. Please choose the binary distribution for non-unix systems.

2004-03-20crt8040_src_20040320.tar.gz

Extract the archiv somewhere and execute 'make' in the main directory. The source will be assembled and all the .crt files in the crts subdirectory will be converted.

Binaries

2004-03-20crt8040_bin_20040320.zip

The archive contains some demo roms in binary format. Use the flash utility shipped with your retro replay to transfer them.
The demo roms:

Convert other crt files

To convert other cartridges, first make sure they are the right type. This header can only be used for crts which start at $8000 and have a size of $4000 bytes.
Check this in 2 steps:
  1. The filesize must be 16464 bytes
  2. Start your favourite hex editor / viewer and look for the byte sequence $80 $00 $40 $00 around offset $4c.
0000  43 36 34 20 43 41 52 54  52 49 44 47 45 20 20 20  |C64 CARTRIDGE   |
0010  00 00 00 40 01 00 00 00  00 00 00 00 00 00 00 00  |...@............|
0020  48 2e 45 2e 52 2e 4f 2e  00 00 00 00 00 00 00 00  |H.E.R.O.........|
0030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0040  43 48 49 50 00 00 40 10  00 00 00 00 80 00 40 00  |CHIP..@.......@.|
                                           ^^ ^^ ^^ ^^
...or just convert the crt and see if it works. :)

Copy the .crt's into the crts subdirectory of the source distribution. Execute 'make' in the above directory.

Feedback

The best place to give some feedback is the Retro Replay Mailinglist. Go here to get subscribed. If you own a Retro Replay this is a good idea anyway.
Please choose a private mail only for topics not suitable for the list.

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