| ??? 09/09/04 16:37 Read: times |
#77146 - RE: Atari 400/800 implementation with 80 Responding to: ???'s previous message |
1) the machine should have all its flashes reprogrammable without removing the dice. Otherwise debug will be hell, besides, with such an "open source" architecture, allowing the user to hack the video chip "firmware" would be a great feature. :) Agree that all flashes should be reprogrammable in-circuit. 2) Support for external mass storage like a hard drive - yes. Necessity - no. I think the OS should be on a built-in medium so you could load the software from arbitrary source (or even enter it by hand.) Hmmm, perhaps the I/O device could have the option of connecting to a storage "device" that is actually a flash IC or EPROM? That'd accomplish the same thing. From the standpoint of the central CPU it doesn't matter where the I/O chip gets the OS from as long as it gets it. A "default" OS could be included in the default firmware for the I/O chip so that the hardware could be booted with no storage and to provide a way to format mass storage in the beginning. This would avoid the problem of how to get an external store device to boot the first time when it has no OS loaded on it in the beginning. Conclusion: Store whole OS in the flash (even may be compressed) just after the tiny bootstrap and make the bootstrap copy it to XRAM on startup before passing control to the external memory. I think that's a possible option but again I think that should be implemented as an optional storage device of the I/O chip. I believe the central 8052 must request that the I/O chip provide the OS at bootup. Whether the I/O chip boots off of flash, EPROM, SD card, IDE hard drive, serial connection, etc. need not concern the central 8052. It's essentially a matter of selecting the boot device and that would be something the I/O chip would have to deal with. Regards, Craig Steiner |
