Minimig Harddisc
Contents
SCSI
P-ATA
- Gayle style IDE is very simple, i've been looking into it. though bluea would probably be the best person to ask about it, he has it working on natami i believe. Most of the signals come straight from the CPU, which means very few FPGA pins will be needed.
- from what i can see, the only lines that dont come straight from the CPU are.
- IDE_CS1
- IDE_CS2 (usually only used by IDE doublers, can probably be left out)
- IDE_IRQ (not needed when interfacing drives to MCU's, not sure whether scsi.device needs it)
- IOWR
- IORD
- WAIT
- what do you know... exactly 6 extra lines
- The data lines are byte swapped
- And IDE_A0 - IDE_A2 are mapped to A2 - A4
- finally, IDE_LED, optionally goes to an LED.
- an IDE only mode compact flash port, could easily be added to the bottom side of the board. :Giving us access to 1.8" hard drives.
S-ATA
Software aspect
- UAE's Hardfile format. In addition to UAE's normal hardfile format (that works as a simplepartition) UAE also has the option of making an entire HD image, including RDB.
- Starting from kickstart 37.300 (I think it's Rom 2.05, earlier releases had a bug and didn't detect it) the controller is supported and code is built-in in the rom.
- For kickstart 1.3 I guess that a driver would be required, simulating an autoconfig HD controller or maybe it would be enough to extract the rom from KS and make a custom 1.3 rom... but I guess I could live without HD emulation on OS1.3 since OS 2.05/3.1 could be loaded in the same board with just a reset.
- I guess Gayle emulation would be perfect. Maybe Thomas Hirsch aka "bluea" could give some hints. He has implemented Gayle emulation for his NatAmi project. I don't know if he'll release some code. Anyway here you have some interesting info about Gayle:
- http://www.amiga.org/modules/newbb/viewtopic.php?topic_id=31439&forum=8#forumpost378020
- He got it working. According to him "I implemented the A4000 and A1200-Gayle registers as a Chip-Select logic for an 2.5" harddisk. So I can boot from that drive."
- -edit- BTW, if a 16 or 32MB memory chip was used there would be room to have 2MB of chip, 8MB of fast and also some "slow-ranger-pseudofast" ram. In addition to the FPGA code and AmigaOS Rom (the fpga code could be changed to accept 1MB roms like CD32/A1200) the rest of ram could be used as buffers for the hardfile. That way disk access shouldn't be too slow.
