Archive for February, 2011
Based on forum feedback, I have refined the Micro ZoomFloppy design for fit and function. Many people comments on the non-optimal placement of the USB connector. I noticed that as well, but the original design goal was to provide maximum installation flexibility. Placing the USB connector on board eliminated the need to mount a USB jack on the case. Installers could simply connector a suitable cable to the connector and let the cable ass through the case at some convenient point. However, the idea was abandoned when others pointed out that the placement of the connector would interfere with other ICs on the drive PCB in many drive configurations. The new design places the USB connector on a separate PCB assembly, which connects to the main board via a 4 wire cable.
The 1541 parallel cable connector remains on the layout. Even when the board is populated, the parallel connector can be used by another ZoomFloppy device for parallel operations.
Other changes were smaller:
- Jumpers were added to bridge any signals that were not passed through the connectors. This allows the design to be used without the uC and related circuitry as a simple parallel cable connector board.
- The 1571 parallel cable connector was added to the design. Again, this is useful when the board is unpopulated and would then be installed in the 6526 socket on a 1571 drive. Unlike the 1541 parallel connector, this connector does not serve a function when installed in the 1571 6522 socket.
Now, the software must be modified and tested for correct operation before the PCB can be assembled.
During a discussion on the Lemon64 forum, someone suggested a version of ZoomFloppy that would fit inside the CBM drive. After some tweaks to the idea, I hereby present “Micro ZoomFloppy”. This unit will sit in the 6522 IC socket and provides complete ZoomFloppy functionality. The only external connection is a USB jack
Though the board looks finished, it’s just a rough draft. Some pin changes would help with layout, and I still have one wire to route. Still, it is coming along nicely.
In case you’re wondering, the 2×8 connector on the bottom is the parallel port header. The PCB serves double duty. When fully populated, it’s a complete ZoomFloppy unit. But, if not populated, it can still be used to add parallel port capabilities to a 1541 device.
Due to some changes in the PCB houses my assembler uses, and cost issues with the DIN6 connector for the uIEC/SD daughtercard, it’s actually cheaper to create a new PCB design than to use the old one. To that end, I have slightly modified the design to include a power supply connector and a switch to disable the RESET line (in case you wanted the device to stay in a subdirectory across reboots of the computer). To stay on delivery targets, I need to send this off to the assembly house this week, but I am interested in comments on the changes and any others that might be possible. Before people ask, I attempted to add a second IEC connector, but then the IEC connectors must be positions to face the side, and the board ends up larger than the uIEC/SD itself.