I've finally had time to work on the cassette interface for the replica 1 and I have the prototype working. I'm doing another prototype run this week because the prototype board I have now was with my old board mfg company. I decided to go with a 90% look-alike but I made one noticable change with the PROM's. I'm going to use the 28C64 in place of the 2 PROM's because of the availability of the EEPROM's vs. PROMs and a few other reasons. I also added decoupling capacitors to all the IC's to help reduce noise. Other things I've done was to label the IC's and resistors and the capacitor.
As with everything I develop for the replica 1, the cassette interface is apple 1 compatible and will have the standard .156" slot edge to work with the Apple 1 or clone computers with .156" slots. For the replica 1, the expansion interface board will be required.
First test is with replica 1 SE and replica 1 rev B. Both machines work quite well using TRS-80 CC81 tape drive and a "everyday use" tape.
I'm using 3.5mm stereo cables and they work great. The replica 1 is equiped withe the new Slot Expansion interface board with a 6" IDE cable between the expansion board and the replica 1.
I have been able to store and reload every program so far with the cassette interface without any problems. The reliability far exceeds what I had wished for.
Phase 2 will involve recording to my laptop and reloading using wav file player. If this works good, I'll convert to MP3 and see if there is any hope it will work with compression. We will see.
Final Phase will be trying the cassette interface with PDA (sorry, no ipod) for a small footprint format. Here is a photo of the layout of the board in pdf format for viewing. I'll have real pics next week.