I'm going to try to design and build a small 65C02 based device. Proposed features will include: 1. Switchable clock rate. 32.768KHz when on batteries, 3MHz on "mains". (Can 65CXX family be run at lower clock rates?) 2. Runs off 4 NiMH AA batteries. (Minimum component charging circuitry please, assuming guaranteed input voltage, variable amperage. Would a regulator changing from 4.8V to 5V need cooling? I read CMOS devices can operate over a range of voltages; does this include CPUs, and what implications would driving the chips at 4.8V have? Would regulation be advised to compensate for discharge curves, or are NiMH relatively flat like I remember NiCad being described somewhere.) 3. A parasitic RS232. As well as performing RS232 the interface will extract power from the DTR line. This power will charge the batteries and assist running. (Will RS232-TTL drivers work with CMOS circuitry? How much power can be safely extracted whilst allowing standard drivers to operate?) 4. 8 character display. (I was thinking of using a 10 character intelligent serial access LED display. It was quite expensive. I want to reserve at most 240 bytes memory mapped I/O for accessing the display - can anybody suggest a better solution with a minimal component cost that's cheaper?) 5. 6 buttons, speaker and lights. 6. 64K NVSRAM (I don't want to use DRAM, since at these sizes the price difference is not important. Should I battery back, or is there a nice cheap truly NV SRAM chip with unlimited writes?) Also, where is the site with virtually every spec sheet in existance? -- Atoms has finally been released! www.doldev.freeserve.co.uk-- Subcription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" to
Wear-Hard Mailing List Archive (searchable): http://wearables.blu.org
From Wear-Hard Mailing list Archive (WH)
Maintained by R. Paul McCarty
Archive created with babymail