Thanks for all the information, I thought the M23P was similar in configuration to the M68.
If I trust the description on
this page about the M23P, the I/O address should also match the M23 exactly. I will continue to analyze the boot sector of the BASIC disk.
Today, I did the following.
Consideration of M23P Floppy Disk Format
The FDD of M23P is Sony OA-D31V. Also, SONY SMC-70/777 (sold only in Japan?) has the same FDD (Sony OA-D31V). By the way, SMC-70's FDC is MB8876.
The FD format of SMC-70 is 70track,1side,16sectors,256byte/sector, so the capacity is 286720byte(280kb).
Wikipedia's article for the M23P states that the capacity of the FD is 290kb; if Wikipedia's description is correct, the FD format for the M23P could be 72 track (288kb) or 73 track (292kb).
Also, the RPM is double speed (600RPM), so if you use FDD emulator, you need to set it properly. FlashFloppy seems to be able to set RPM. The FlashFloppy seems to be able to set the RPM, but I don't know if it can actually emulate 600RPM. HxC seems to be able to set it. This discussion is of course irrelevant when writing to a real FDD.
Creating a boot disk image of M23P
If the boot ROM of M23P is similar to the code of M68, it should read 2kb (0track, 0side, 1-8sectors) at boot time.
You can create a disk with a small monitor program written in these sectors and try to actually boot it.
First, we created a disk image(
track70_smc70.img) with the same format as the SMC-70 (70track, 16sectors, 256byte/sector). At the same time, disk images of 72track(
72track.img) and 73track(
73track.img) were created. All images are raw.
The monitor program I wrote is a version of
Universal Monitor with some functions removed.
The experiment of booting M23P
This experiment requires several pieces of equipment.
1. USB to RS232C cable
2. a serial cable adapter (DB9 to DB25?) adapted to the M23P
Connect the M23P to a Windows machine via the above cable, run the appropriate terminal software on Windows, and make the following settings.
9600bps, 8bit, No-parity, stop bit1
The configuration code for the Z80CTC of the M23P was slightly different from that of the M68. If there is no response at 9600bps, try changing the baud rate.
Set up a disk image on the M23P, or physically insert an FD and let it read the disk after resetting.
If you see any text on the terminal screen, you have succeeded.