HP48-Ramcard-FAQ

HP48-Ramcard-FAQ V1.1 28.5.97

1. What kind of chips are known to work? Any 128kx8 static RAM in SMD package should work. On my cards I am using: Intel PG51018SL-10 Hitachi HM628128LFP-10 2. How fast should the RAM be? I don't know, but I think you can use really slow RAMs because of the slow CPU inside the HP48. Everything between 70ns and 120ns should work. Don't use fast PC-Cache-Ram because they need to much power. 3. Where can I buy the Ram? I am living in Germany. I think it makes really no sense if I tell you American, Spanish, Russian, Australian or whatever people where I bought my RAMs. German Users may have a look at Reichelt or Simons. And sometimes you found the ramchip on a defekt harddisk :) 4. How thin/thick are the PCB's? 2mm 5. What are '.ps' (postscript) Files and how can I print them? You have to buy a postscript printer or search for a program called ghostscript. I really don't know nothing about windows or microsoft. Please, don't ask me so stupid boring questions! Stupid questions only for Linux, or my old Apple II+ :-) 6. Are these cards working in an HP48GX, too? I only have an HP48SX but people told me that they are working in a GX. 7. Is it possible to build bigger cards? (256, 512k, ...) Yes, but I don't know how to do it. It is not easy because you need some kind of bankswitching. I don't think of building such cards. 8. What did you use for mounting the battery in the ramcard? Use some kind of adhesive tape for the first test and when you trust your card fill the whole PCB with transparent 2-compounds-epoxy-glue. The battery I used are a little bit bigger than the original HP-Type. They should last more than 10 years, enought time to buy a HP-999999 :) Ups! I am wrong with the last point. Now the HP49 is out and looks really ugly. But the buttery on my first card now lasts for five years. No Problems yet.