The 64NIC+ provides Ethernet access for the Commodore 64 and 128 systems. It offers low-cost RR-NET/TFE/FB-NET compatibility. Jim Brain designed the cartridge, based on an earlier Eric Pratt design and incorporating ideas from Fotios' FB-NET design. Bil Herd (of C128 design fame) provided assistance on the design as well. The device's development was sponsored by the Cincinnati Commodore Computer Club and currently offers the unit for sale. While there are many multi-purpose cards with Network Interface Card (NIC) functionality today (1541U, Retro Replay +RR-NET), 64NIC+ provides dedicated NIC functionality.
Much like contemporary network cards, the 64NIC+ provides support for an optional "boot ROM". If a suitable EPROM is installed, the device can boot a ROM-based OS or load an OS from the network. Switches offer the option of booting into 64 mode or 128 mode (on a C128).
At the 2008 World of Commodore Expo, CCCC asked Jim Brain about the possibility of a low-cost Ethernet cartridge. Initial ideas were to clone the FB-NET cartridge or produce Pratt's C64NIC design. The FB-NET design was discarded, due to cost issues and a desire to fit the design in a standard cartridge case. An initial design based on C64NIC was created, and a subsequent design revision added ROM capabilities based both on suggestions from buyers and also realization of much unused board space in the design.
As the design progressed, Bil Herd offered some suggestions to decrease signal degradation and clean up read/write signal timing to allow C128 FAST mode operation.
The unit contains a Crystal CS8900A Ethernet controller and the necessary 6502/6510 to ISA interface logic. Onboard switches select the IO bank in use and register mappings.
The optional ROM socket supports 8kB to 256kB EPROMs, offering 1-16 16 kB ROM "images", selectable via a 16 position rotary switch. By default, the boards are configured for a 27C010-27C020 (32 pin JEDEC) ROM. They can be switched to 27(c)64 to 27(c)512 ROMs by cutting the '32' side of JP4 and soldering the '28' side. This will direct Vcc to pin 28 instead of pin 32. Additionally, jumper JP2 can be removed to allow 8kB ROM images to be used on the C64.
Note that images are 16kB in size (unless JP2 is changed), so 8kB C64 images need to be padded with a copy of BASIC v2 in the upper 8kB bank of the image. As well, if the 16 position image selector switch is not installed, only the highest bank will be visible.
There are two versions of the hardware:
- Model v1.0
- Model v1.0a
The difference is the lack of a jumper from switch S3 to switch S2. The missing pin on S3 must have a jumper wire connected to the middle of S2 for the EPROM socket to work correctly. With this modification, the boards function identically.
 Hardware Features
 Where can I find more information?
 How do I get one?
 Will it play nice with a 1541U batch 1, or AR cart on a 2+1 extender? ?
It mainly depends on whether those cartridges decode IO1 or IO2 addresses. If they leave one of the IO banks available, the 64NIC+ (or any other Ethernet cart) will work. If they take over both IO ranges on the cart port, then it will not work.
 What do the switches do?
- S1 selects whether standard or "RR-NET" register mappings are to be used
- S2 selects EPROM usage
- S3 selects C128 or C64 EPROM usage
- S4 selects IO1 or IO2 register space.
 What do the LEDs mean?
- RED : Power
- Green : Activity