C264Cart

The C264Cart ist a modernized ROM cartridge for the Commodore 264 family of 8-bit computers, the Commodore C16, C116, and Plus/4.

I started out by first reverse engineering and replicating the layout of an original ROM cartridge. Then I adapted it to better suit EPROMS and EEPROMS that are still readily available today, such as the W27C512 and W27C020. The layout was also scaled down to save shipping costs, but still fits the original cartridge shells.

See my blog post for more details.

I also created a simplified version of the original cartridge case for 3D printing that works well with the C264Cart. It is currently available for personal use on Thingiverse and Printables.

Configuration Options

There are two things that need to be configured, the type of EPROM to be used and the size of the targeted ROM images.

The C264Cart can be configured to support either 16k ROM images or 32k ROM images by setting JP6 and JP7 accordingly. 32k ROM images for the 264 computers usually consist of two 16k parts that were originally stored in two separate ROMs. On the C264Cart in 32k mode, both parts go into the same EPROM with the upper part directly following the lower one. As a result, A14 cannot be used for external bank switching in 32k mode. It is automatically selected by the cartridge.

If the C264Cart is configured for 16k mode R1, D1, and D2 don't need to be populated. These components are used in 32k mode, only.

The C264Cart supports 27C512, 27C020, and 27C040 (E)EPROMs. Make sure that these ICs are always aligned to the top of the cartridge as indicated on the silkscreen and that the jumpers JP4 and JP5 are set correctly!

27C512 for 4 ROM images with 16k each

Address		A14	A15
0x0000	ROM 1	0	0
0x4000	ROM 2	1	0
0x8000	ROM 3	0	1
0xC000	ROM 4	1	1

27C020 for 16 ROM images with 16k each

Address		A14	A15	A16	A17
0x00000	ROM 1	0	0	0	0
0x04000	ROM 2	1	0	0	0
0x08000	ROM 3	0	1	0	0
0x0C000	ROM 4	1	1	0	0
0x10000	ROM 5	0	0	1	0
...	...	...	...	...	...
0x3C000	ROM 16	1	1	1	1

27C040 for 32 ROM images with 16k each

Address		A14	A15	A16	A17	A18
0x00000	ROM 1	0	0	0	0	0
0x04000	ROM 2	1	0	0	0	0
0x08000	ROM 3	0	1	0	0	0
0x0C000	ROM 4	1	1	0	0	0
0x10000	ROM 5	0	0	1	0	0
...	...	...	...	...	...	...
0x7C000	ROM 32	1	1	1	1	1

27C512 for 2 ROM images with 32k each

A14 must be left open!

Address		A14	A15
0x0000	ROM 1 low	x	0
0x4000	ROM 1 high	x
0x8000	ROM 2 low	x	1
0xC000	ROM 2 high	x

27C020 for 8 ROM images with 32k each

A14 must be left open!

Address		A14	A15	A16	A17
0x00000	ROM 1 low	x	0	0	0
0x04000	ROM 1 high	x
0x08000	ROM 2 low	x	1	0	0
0x0C000	ROM 2 high	x
...	...	x	...	...	...
0x38000	ROM 8 low	x	1	1	1
0x3C000	ROM 8 high	x

27C040 for 16 ROM images with 32k each

A14 must be left open!

Address		A14	A15	A16	A17	A18
0x00000	ROM 1 low	x	0	0	0	0
0x04000	ROM 1 high	x
0x08000	ROM 2 low	x	1	0	0	0
0x0C000	ROM 2 high	x
...	...	x	...	...	...	...
0x78000	ROM 16 low	x	1	1	1	1
0x7C000	ROM 16 high	x

Caption

License

USE AT YOUR OWN RISK!.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.