Hello,
I have design a 8-bit card for mass storage with SD cards. The schematic is here and based on a design I did for the Apple ][.
The designs for the two cards (ISA and Apple ][ bus) are so similar that this kind of serves as a "Rosetta stone" to compare the two busses.
The card has the ability to use a 28C64 or 28C256 option ROM. However, I have never written an Option ROM before. I was taking a look at the one used with XT IDE, the XT IDE universal BIOS and its source code
I am trying to figure out a starting point for adding a block device to the BIOS. The best I have been able to puzzle out would be to try to take the Serial block device and clone and customize that. The interface to the SD card is through a 82C55 in mode 2 to a ATMEGA328P which runs code to access the SD cards. The PC will largely be sending and receiving sectors to the ATMEGA328P, and so hopefully the code that needs to be included in the XT IDE BIOS is minimal. Since most of the heavy lifting is done by the ATMEGA328P, I am hoping that this addition will not be too difficult.
Since the XT IDE was developed here on the forum, does anyone have any guidance how I might go about this?
Thanks,
Dan
I have design a 8-bit card for mass storage with SD cards. The schematic is here and based on a design I did for the Apple ][.
GitHub - profdc9/ISACard: A ISA card for PC/XT/AT that has SD storage and SPI/I2C interfaces using a ATMEGA328P
A ISA card for PC/XT/AT that has SD storage and SPI/I2C interfaces using a ATMEGA328P - GitHub - profdc9/ISACard: A ISA card for PC/XT/AT that has SD storage and SPI/I2C interfaces using a ATMEGA328P
www.github.com
GitHub - profdc9/Apple2Card: Apple II Peripheral Card that Interfaces to a ATMEGA328P for SD card storage
Apple II Peripheral Card that Interfaces to a ATMEGA328P for SD card storage - GitHub - profdc9/Apple2Card: Apple II Peripheral Card that Interfaces to a ATMEGA328P for SD card storage
www.github.com
The designs for the two cards (ISA and Apple ][ bus) are so similar that this kind of serves as a "Rosetta stone" to compare the two busses.
The card has the ability to use a 28C64 or 28C256 option ROM. However, I have never written an Option ROM before. I was taking a look at the one used with XT IDE, the XT IDE universal BIOS and its source code
xtideuniversalbios
www.xtideuniversalbios.org
I am trying to figure out a starting point for adding a block device to the BIOS. The best I have been able to puzzle out would be to try to take the Serial block device and clone and customize that. The interface to the SD card is through a 82C55 in mode 2 to a ATMEGA328P which runs code to access the SD cards. The PC will largely be sending and receiving sectors to the ATMEGA328P, and so hopefully the code that needs to be included in the XT IDE BIOS is minimal. Since most of the heavy lifting is done by the ATMEGA328P, I am hoping that this addition will not be too difficult.
Since the XT IDE was developed here on the forum, does anyone have any guidance how I might go about this?
Thanks,
Dan