I examined the disk image of BASIC for SORD M23 in the Internet archive.
First, I found the following from this disk image:
1. 80tracks, 1side, 16sectors, 256byte/sector. 2. all sectors are MFM record type.
2. all sectors are MFM record type.
3. 256 * 16 * 80 = 320kByte/disk
Next, I disassembled and analyzed what I thought were the boot sectors (sectors 0-6). I found the followingSerial I/O is Z80SIO, Counter is Z80CTC, DMA is Z80DMA, Floppy Disk Controller is unknown, but I think it is MB8877.
FDC is MB8877?
0xc0 : FDC command/status reg?
0xc1 : Track reg?
0xc2 : Sector reg?
0xc3 : FDC data reg?
0xc4 : Z80DMA I/O address
Z80SIO
0xf8 : Z80SIO_A_channel Data reg.
0xf9 : Z80SIO_A_channel Control reg.
0xfa : Z80SIO_B_channel Data reg.
0xfb : Z80SIO_B_channel Control reg.
Z80CTC
0xfc : channel0
0xfd : channel1
0xfe : channel2
0xff : channel3
I don't have an M23, so I can't actually verify it, but once I get the model number of the FDC, more will be revealed.
Knowing the model number of the FDC will allow me to write a small monitor program to the boot sector to get more information.
