Re[2]: [emax] Using Programmed PIC micro Controller
2009-08-08 by tu@...
The boot EPROM would be a good place to start as it must contain code to load the base OS overlay from floppy or SCSI/HDD. Some hacking there could allow the OS code to instead be loaded from another ROM chip added in somewhere on the CPU bus. Saturday, August 8, 2009, 8:40:02 AM, you wrote: > > The Emax main CPU is a National Semiconductor NS32008 and the data sheets are included in the NS32000 Family databook, which is available for free > download from http://www.bitsavers.org/pdf/national/_dataBooks/1986_NS32000_dataBook.pdf > oooh! cool! I hadn't thought to look. > I think the issue is more that without the OS source code and documentation it is a long and grueling task to go through the OS binaries to disassemble > them and understand how they work. There will no doubt also be various design constraints that can only really be discovered by trial and error when > you don't have the original design documentation. Then you still need an assembler to reassemble the modified code.... but it can be done... > actually with the opcodes it should be very possible to disassemble the code, and make changes... yeah it'd be a bit of a slog, but not really much more than what esynthesist already did with the sample format. and people have already done this for other samplers. especially if you're just looking for something like the HDD code, to enable a wider range of SCSI devices, bigger sizes, and more banks... or the boot code, to put the OS onto an eeprom. You'd just need to look for memory accesses at the location where the related hardware is, and then poke around looking for what interacts with that code.