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RE: [N8VEM-S100:4729] Re: ZFDC Controller under control of the PC-BIOS??

Frank you should not be seeing  “EEE13” on the hex display. Booting a 3.5” floppy shows FF003 initially, then it starts counting up the sectors. Would have to look why FF initially, but after first sector the FF goes to 00.  There may be something not quite right with your onboard Z80/RAM/ROM.  Going to the monitor command on the board (from the diagnostic program),  can you display the correct ports eg the HEX display ports etc. 


My setups are different so ports will be different but  the ZFDC ports gave:- 0010->21FF ->21,   0011->FF7E ->7C.


Since you are not even getting a single sector it’s clear the board is having problems reading the disk.   You should concentrate on the disk pins see what signals are coming and going.  Is the head being reset if it is in the center of the disk, are you getting an index pulse for example.  Are you sure you are reading the correct side of the disk.


Sorry to see you are having such problems.





From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Frank Schieschke
Sent: Tuesday, July 29, 2014 12:04 PM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:4729] Re: ZFDC Controller under control of the PC-BIOS??


Hello John,
no, there is no reading at all, when trying to boot from the floppy over the 8086 monitor.
This is the output i get:

8086-80386 Active

80286 Monitor V10.32 (7/19/2014) Stack pointer = D000:FFFC

Booting MS-DOS from 5" Floppy Disk
Initilizing 8259A PIC (Port 20H, Ints 0 & 1 only)
No VGA ROM at C000:0000H
ZFDC Board Initilize OK

Floppy Sector Read Error. Error returned = 3DH

Boot sector read on floppy drive failed.

IBM PC BIOS Initilizing
Initilizing 8259A PIC (Port 20H, Ints 0 & 1 only)
No VGA ROM at C000:0000H

IBM-PC BIOS Test Menu.     (Debug Flag = OFF)
A=Timer Test             B=Propeller/LAVA/VGA    C=MS-DOS Boot (Floppy)
D=Toggle Debug Flag      E=Key Press Test        F=Consol Out Test
G=Keyboard Buffer Test   H=INT 10H CMDs          I=Print Screen Test
J=RAM Byte READ Test     K=RAM Word READ Test    L=RAM Byte WRITE Test
M=RAM Word WRITE Test    O=Out to Serial Port    P=MS-DOS Boot (HDISK)
Q=CHS Hex Display Test   S=5" Floppy Sec RD Test T=3" Floppy Sec RD Test
U=HDisk Sec RD Test      W=HDisk Sector R/W Test Y=Floppy Boot Sec Info
Z=Hard Disk MBR Info     (ESC) Back to Main Menu


The HEX display on the ZFDC controller shows "EEE13" at least.

I take a closer look at my I/O ports. Are these are normal?

Input Ports, 0-0FFFFH Ports.  (16 Bit Port DX->AX and DX->AL)

0000->00FF ->00  0001->C575 ->75  0002->C5FF ->C5  0003->FF00 ->00
000F->21FF ->FF  0010->21FF ->21  0011->FF7E ->7E  001F->01FF ->FF
0020->01FF ->00  003F->CAFF ->FF  0040->D2FF ->44  0063->00FF ->FF
0064->00FF ->00  00EF->FFFB ->FB  00FF->00FF ->FF
Continue ? (Y/N).


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