15210Re: First ELF project
- Aug 6, 2014Hi Jon,
An oscillator can will work fine, the 1802 isn't fussy. Pump it into pin 1, clk, ignore pin 39.
Those can's produce a nice square wave!
If you look at the VELF a little closer, you will see that the EPROM starts at 0000-7FFF then gets remapped to 8000-FFFF on the first occurrence of A15 going high. It's first instruction is then a long jump to 8003, the next instruction fetch remaps the EPROM and lets the RAM operate at 0000-7FFF. If you flip the mode switch to ELF, it simply forces the EPROM to be at 8000-FFFF and keeps RAM in the lower 32K. In this mode, you can just toggle in C0 80 00 to go into the monitor.
But, I totally agree with your original plan. Build the basic ELF, and then start modifying it. I will recommend 2 options. 1. Either do it on a large perfboard for expansion or 2. Do it on one of those perfboards with a card edge connector, then build a mother board so you can plug in other boards to your system as it grows.
- << Previous post in topic Next post in topic >>