Exidy Sorcerer Floppy Disk Controller (Dreamdisk) Replica PCB

[Exidy Wizard]

@ JLtursan:

I've found the assembler listing of the Monitor software 1.3 from the brothers van Monfort. It can be found here:

https://www.pe1abr.nl/home-server/download/EXIDY/Montfort_Monitor_1.3_voor_Exidy_Sorcerer__max-versie.pdf

The assembler source is only in Dutch. The explanation is both in Dutch and English.

 

[RedskullDC]

Hi Exidyboy,

Saw your post pertaining to issues with the controller on the Sorcerer forum.
Email direct if you keep having trouble.

Can you expand on how it is checking for a disk controller and how it chooses which drive to boot from?

Sure.

Check_Port_48 routine:
Is checking that the latch on the Dreamdisk at port 48h is present and active.
The $1E bitmask will select the drives momentarily and set the DDEN bit on the controller, and leave them all active(?) (IIRC).

EECF: sends a "restore to track ZERO" command to the 2793 FDC
EED7: selects Sector#1
EEDE: sets a bit mask to select drive#0.

EEE2: sets up a small routine at 0066h (halt vector) which reads from port C, saves to HL, increments HL and returns.

EEF3: sets up to read $80 byes (1 sector) to 0080h, and sets the C register to $47 (2793 data read register.

EEF9: Read sector routine reads the bytes in groups of 4 through the routine set up at the HALT vector.
once $80 bytes have been read, waits for the FDC to finish, and passes the status bits through to the loaded sector,
which can then check for CRC, lost data etc. errors.

Cheers,
Leslie

 

[exidyboy]

Hi Exidyboy,

Saw your post pertaining to issues with the controller on the Sorcerer forum.
Email direct if you keep having trouble.

Thanks. Have sent you an email but it might have gone to spam since my email address has changed subtly which seems to hurt the feelings of some email providers/clients. However a fix for the writing problem has been identified.

Sure.

Check_Port_48 routine:
Is checking that the latch on the Dreamdisk at port 48h is present and active.

Thanks for the analysis. I've long been perplexed by the presence of that 74LS244 on the output lines going to the drive select and side select driver. Would it be fair to say that its job is to allow the software to verify that a Dreamdisk controller is plugged in by reading the status of those signals?

 

[RedskullDC]

Hi Exidyboy,

No, haven't seen your email. Will check Junk/Spam when I get home this evening.

Would it be fair to say that its job is to allow the software to verify that a Dreamdisk controller is plugged in by reading the status of those signals?

In my opinion, absolutely.

Routine is looking for a WD type floppy controller there.

Cheers,
Leslie