creating an SDcard for FLEX - nealcrook/multicomp6809 GitHub Wiki

I use a single SD card on which co-exist "ROM" BASIC, "BUGGY", "CUBIX", "FLEX", "NITROS9" and "FUZIX" images. The key is to use a fixed offset for each image and to code the driver routines to calculate blocks relative to that offset. I did not write the CUBIX drivers so I have put its files at offset 0. I use a script to build an image file and then I copy the image to the SD card. The image file can also be used by the virtual SD interface of the emulator.

The script to build the image file is in the repository as bin/create_sd_image and looks like this:

# Create image file for multicomp
# SDcard is 2GByte so everything must fit within that footprint.
#
# the resultant image can be transferred to and SDcard using dd (Linux) or RAWWRITE (Windows).

# CUBIX file system
# ~35MByte, at offset 0.
dd if=fpgacubix.img of=multicomp09_sd.img

# CUBIX boot ROM
# 2Kbytes at offset 64Mbyte
# 64MByte is block offset 1048576 * 64/512 = 0x2.0000
dd if=r09sase.bin of=multicomp09_sd.img obs=1M seek=64


# FORTH block files (optional)
# 4 files each of up to 256Kbytes, starting at offset 65MByte
# Block offset 256*1024 * 260/512 = 0x2.0800 (260 = 4*65)
dd if=forthblk0.blk of=multicomp09_sd.img obs=256K seek=260
# Block offset 256*1024 * 261/512 = 0x2.0A00
dd if=forthblk1.blk of=multicomp09_sd.img obs=256K seek=261
# Block offset 256*1024 * 262/512 = 0x2.0C00
dd if=forthblk2.blk of=multicomp09_sd.img obs=256K seek=262
# Copy of CamelForth Chromium source (just to give some text to look at!)
# Block offset 256*1024 * 263/512 = 0x2.0E00
dd if=chromium.scr  of=multicomp09_sd.img obs=256K seek=263


# BASIC ROM
# 8KBytes at offset 66MByte
# 66MByte is block offset 1048576 * 66/512 = 0x2.1000
dd if=EXT_BASIC_NO_USING.bin of=multicomp09_sd.img obs=1M seek=66


# Binaries for FLEX bootstrap
# 3 blocks-worth at offset 67MByte
# Block offset 256*1024 * 268/512 = 0x2.1800
dd if=multicomp09_flex_qload.bin of=multicomp09_sd.img obs=256K seek=268
# Block offset 256*1024 * 269/512 = 0x2.1a00
dd if=multicomp09_flex_io.bin    of=multicomp09_sd.img obs=256K seek=269
# Block offset 256*1024 * 270/512 = 0x2.1c00
dd if=multicomp09_flex_sd.bin    of=multicomp09_sd.img obs=256K seek=270

# Binary for bootstrap of debug monitor (14 blocks)
# Block offset 256*1024 * 271/512 = 0x2.1e00
dd if=multicomp09_flex_buggy.bin of=multicomp09_sd.img obs=256K seek=271


# Drive 0: FLEX system disk
# (Allow) 3MBytes at offset 68MByte
# 68MByte is block offset 1048576 * 68/512 = 0x2.2000
# This is being developed in the flex directory
# there is a multicomp09_flex.dsk which needs to be expanded to
# 512byte sectors.
flex_disk_manip multicomp09_flex.dsk -outsd multicomp09_flex.img
dd if=multicomp09_flex.img of=multicomp09_sd.img obs=1M seek=68


###############################################################
## Drive 0 (above) is all that you need to boot FLEX. The lines
## below add additional disk images for Drive 1, Drive 2 and
## Drive 3. If you don't have any other .dsk files then just
## use copies of Drive 0 like this:
## flex_disk_manip multicomp09_flex.dsk -outsd flex_drive1.img
## ..
## ..
##
## You *need* something here for these 3 drives, otherwise
## FLEX will get very upset if you ever reference a drive
## other than Drive 0.
##
## For a good source of FLEX disk images install Michael
## Evenson's SWTPC6800 emulator, from:
## http://www.evenson-consulting.com/swtpc/Downloads.htm
###############################################################


# Drive 1
# (Allow) 3MBytes at offset 71MByte
# 71MByte is block offset 1048576 * 71/512 = 0x2.3800
# The .dsk file needs to be expanded to 512byte sectors.
flex_disk_manip ../flex/adventure.dsk -outsd flex_drive1.img
dd if=flex_drive1.img of=multicomp09_sd.img obs=1M seek=71

# Drive 2
# (Allow) 3MBytes at offset 74MByte
# 74MByte is block offset 1048576 * 74/512 = 0x2.5000
# The .dsk file needs to be expanded to 512byte sectors.
flex_disk_manip ../../flex09_dsk_files/CEDRIC.DSK -outsd flex_drive2.img
dd if=flex_drive2.img of=multicomp09_sd.img obs=1M seek=74

# Drive 3
# (Allow) 3MBytes at offset 77MByte
# 77MByte is block offset 1048576 * 77/512 = 0x2.6800
# The .dsk file needs to be expanded to 512byte sectors.
flex_disk_manip ../../flex09_dsk_files/SBUG.DSK -outsd flex_drive3.img
dd if=flex_drive3.img of=multicomp09_sd.img obs=1M seek=77


###############################################################
# NITROS9 boot disk
# (Allow) 2MBytes at offset 80MByte
# 80MByte is block offset 1048576 * 80/512 = 0x2.8000
# The .dsk file needs to be expanded to 512byte sectors.
nitros9_disk_manip nos96809l1v030300mc09_80d.dsk -outsd nitros9_0.img
dd if=nitros9_0.img of=multicomp09_sd.img obs=1M seek=80

###############################################################
# NITROS extras disk 1
# use the "toolshed" utilities to create a disk image like this:
# os9 format -e -t80 -ds -dd nitros9_1.dsk -n"NitrOS-9/6809 Level 1 util disk1"
#
# (Allow) 2MBytes at offset 82MByte
# 82MByte is block offset 1048576 * 82/512 = 0x2.9000
# The .dsk file needs to be expanded to 512byte sectors.
nitros9_disk_manip nitros9_1.dsk -outsd nitros9_1.img
dd if=nitros9_1.img of=multicomp09_sd.img obs=1M seek=82

###############################################################
# NITROS extras disk 2
# (Allow) 2MBytes at offset 84MByte
# 84MByte is block offset 1048576 * 84/512 = 0x2.A000
# The .dsk file needs to be expanded to 512byte sectors.
nitros9_disk_manip nitros9_2.dsk -outsd nitros9_2.img
dd if=nitros9_2.img of=multicomp09_sd.img obs=1M seek=84

###############################################################
# NITROS extras disk 3
# (Allow) 2MBytes at offset 86MByte
# 86MByte is block offset 1048576 * 86/512 = 0x2.B000
# The .dsk file needs to be expanded to 512byte sectors.
nitros9_disk_manip nitros9_3.dsk -outsd nitros9_3.img
dd if=nitros9_3.img of=multicomp09_sd.img obs=1M seek=86

##this is a much bigger image, but it runs from the same start
##point and so the driver should be able to cope without modification
##nitros9_disk_manip VCCEmuDisk.vhd -outsd nitros9_3.img
##dd if=nitros9_3.img of=multicomp09_sd.img obs=1M seek=86


###############################################################
# FUZIX Kernel
# (Allow) 1MByte at offset 96MByte
# boot loader: load and execute at 0xd000
# 96MByte   is block offset 1048576/2 * 192/512 = 0x3.0000
dd if=fuzix_boot.bin of=multicomp09_sd.img obs=512K seek=192
# Kernel: loaded by the boot loaded
# 96.5MByte is block offset 1048576/2 * 193/512 = 0x3.0400
dd if=fuzix.bin      of=multicomp09_sd.img obs=512K seek=193

###############################################################
# TODO FUZIX Swap file
# Reserve 1MByte at offset 97MByte
# 97MByte is block offset 1048576 * 97/512 = 0x3.0800

###############################################################
# FUZIX Root file system
# 32Mbyte at offset 98MByte
# 98MByte is block offset 1048576 * 98/512 = 0x3.1000
# The root file system is in FUZIX format
dd if=fuzixfs.dsk of=multicomp09_sd.img obs=1M seek=98

###############################################################
# FUZIX Additional file system
# 32Mbyte at offset 130MByte
# 130MByte is block offset 1048576 * 130/512 = 0x4.1000
# The root file system is in FUZIX format .. TODO? 512 or 256?
#dd if=fuzixfs_blank.dsk of=multicomp09_sd.img obs=1M seek=130

Each group of images is independent, you can omit any that you are not interested in, and the others should still work. If you only want to run the disk image that I already created you only need to include the multicomp09_flex.dsk image.

The step involving "flex_disk_manip" is worth special mention. The SD card uses a block size of 512 bytes. FLEX uses a sector size of 256 bytes. It would be possible to pack 2 sectors per block but that requires additional complexity in the software. It's far simpler to just use the first 256 bytes of each block. With the arguments shown, flex_disk_manip reads in the .dsk file and duplicates each incomimg sector in the output file that it generates. It can also perform the reverse procedure (so if you extract a disk image from an SD card you can crush it back to .dsk format, halving its size in the process.

Similarly, NITROS9 floppy disk driver uses a block size of 512 bytes (unless you use the superdriver) so "nitros_disk_manip" performs the same function for NITROS9 disk images.

Copying the SD card image onto an SD card

You can't just mount the card and copy the .img file - that would subsume the .img file within the file system on the SD card. Instead, you need the SD card to hold a literal binary copy of the .img. The traditional way to do this in Linux is to use dd. On Windows, "RAWRITE32" is probably the thing to use. Grant's original multicomp SD controller only supported standard density cards (cards of 2GByte capacity or less). The latest RTL in my repository supports both SDSC and SDHC cards so that restriction no longer applies.

The motivation for supporting SDHC is that 2GByte cards aren't easy to come by any more in the high street. If you need one, and can't find one in an old phone or Nintendo, they are (still) readily available on ebay.