Stub page for XT-FDC project

Introduction

The XT-FDC is an 8 bit ISA board based on the National Semiconductor PC8477B floppy disk drive controller chip, a chip that supports up to four floppy disk drives. It will support up to four floppy drives internally with an optional external connector for two of those. It will have the same parameters as the XT-IDE project in terms of size, cost, availability, etc.

Hardware functionality included is:
1. Basic FDC.
2. Configurable IO ports, interrupts, and DMA.
3. Optional boot ROM.
4. Optional ROM drive (MAY13: No supporting software - none currently planned).
5. Optional connector for external floppy drive (self-powered).
6. Optional use of a DP8473V controller chip in socket U2 instead of a PC8477B controller chip in socket U16.
6. Optional use of an 82077AA controller chip in socket U16 instead of a PC8477B. (See 'Known Problems/Issues' section below.)
7. Optional connector for 8" drive (no guarantee of suitability).

The XT-FDC board is a do-it-yourself home brew computing project. PCBs will be available for builders to source their own parts. They assemble and build and test their own boards. Assuming things continue similar to the XT-IDE V2 project, it is anticipated the PCBs will cost $12 each plus shipping.

The XT-FDC idea originated here
http://www.vintage-computer.com/vcfo...card-I-on-eBay
and continued here
http://www.vintage-computer.com/vcfo...el-of-interest

Medium resolution photo

http://www.minuszerodegrees.net/xtfd...at_07apr13.jpg

Alternate controller chips

The primary intent is for a National Semiconductor PC8477B floppy disk drive controller chip to be used in socket U16.
There are two other options:

1. Intel 82077AA
In socket U16, an 82077AA is used in place of the PC8477B. Note that the -5 version of the chip (i.e. 82077AA-5) does not support 2.88M drives.

The use of an 82077AA has two unique requirements:
* Capacitor C23 in place.
* Jumper JP10 on.

At May 2013, only one tester has the 82077AA working in the XT-FDC. See the 'Known Problems/Issues' section below for more information.

2. National Semiconductor DP8473V
Nothing in socket U16, and a DP8473V in socket U2.


History / status

September 2012: Poll by lynchaj seeking interest.
September 2012: First version of prototype designed.
September 2012: Build-and-test team determined. People who are are experienced in board building and debugging.
September 2012: lynchaj acquiring and distributing 5 of the prototype PCBs.
October 2012: Build-and-test team starts work.
October 2012: Chuck(G) discovers a flaw in PCB design (concerning chip U6).
November 2012: Continued testing and redesign.
December 2012: Redesign continuing.
January 2013: sergey posts his BIOS for testing. 4-drive support, built-in BIOS configuration editor, etc.
February 2013: Design of the second-revision prototype board complete.
March 2013: lynchaj acquiring 20 of the second-revision prototype PCBs.
March 2013: lynchaj distributing those PCBs.
April 2013: Testing continuing.
May 2013: Testing continuing.

Points of contact

http://www.vintage-computer.com/vcfo...?3458-Chuck(G)
http://www.vintage-computer.com/vcfo...p?3051-lynchaj

Project files

Project files are certain documents such as the schematic diagram. The latest project files are at the URL that follows.
Please notify one of the above points of contact if you detect a fault/problem in the file content.
http://n8vem-sbc.pbworks.com/w/brows...r&param=XT-FDC

Jumper settings

Separate jumper diagrams have been created for the four major functionalities.
1. Basic FDC
2. Boot ROM
3. ROM drive
4. DP8473V in socket U2

Known problems/issues

1. 82077AA chip

MAY13: It was anticpated that an 82077AA chip would work in socket U16. It works in modem7's second-revision prototype board, but not in the second-revision boards of nestor nor Kiwisek. For now, just be aware that there is a risk of the XT-FDC not working if an 82077AA is used.

2. 360K Drives

Some 360K drives generate a signal on pin 34. For 360K drives that do, that will be a READY signal. A READY signal will be a problem for the XT-FDC. If you intend to connect a 360K drive to the XT-FDC that generates a signal on pin 34, then disconnect pin 34. Some drives have a jumper that can be removed to achieve that (e.g. the JU-455-7 has an 'RY' jumper).

For information, that requirement is not unique to the XT-FDC board. The IBM 5162 and 5170 computers have the same requirement.

Note: 1.2M drives will be expected to generate a DISK CHANGED signal on pin 34.

3. "ROM" Errors

The following problem was fixed in version 2.2 of Sergey's BIOS:

On the IBM 5150 (later model), the following errors will be seen on computer power on: F660 ROM, F860 ROM, FA60 ROM, FC60 ROM
On the IBM 5155 and IBM 5160, the following errors will be seen on computer power on: F6600 ROM, F8600 ROM, FA600 ROM, FC600 ROM

Parts list

Code:
  +------------------------------------------------+
  |                                                |
  |  FOR: FIRST-REVISION PROTOTYPE XT-FDC CARD     |
  |                                                |
  +------------------------------------------------+
3eeschema (2012-08-04 BZR 3667)-testing  >> Creation date: 9/16/2012 4:25:54 PM

#Cmp ( order = Reference )
| BUS1       BUSPC       ; BUS_PC      
| C0         47uF        ; C1V7        
| C1         510 pF      ; C1          
| C2         .1uF        ; C2          
| C3         .1uF        ; C2          
| C4         .1uF        ; C2          
| C5         .1uF        ; C2          
| C6         .1uF        ; C2          
| C7         .1uF        ; C2          
| C8         .1uF        ; C2          
| C9         .1uF        ; C2          
| C10        .1uF        ; C2          
| C11        .1uF        ; C2          
| C12        10 pF       ; C1          
| C13        10 pF       ; C1          
| C14        10 pF       ; C1          
| C15        10 pF       ; C1          
| C16        .1uF        ; C2          
| C17        .1uF        ; C2          
| C18        .1uF        ; C2          
| C19        .1uF        ; C2          
| C20        .1uF        ; C2          
| C21        1000 pF     ; C1          
| C22        .1uF        ; C2          
| C23        4.7 nF      ; C1          
| C2A-1      0.033 uF    ; C1          
| C2B-1      0.015 uF    ; C1          
| C2C-1      0.012 uF    ; C1          
| J1         DB37        ; DB37FC      
| JP1        ROM ENABLE  ; SIL-2       
| JP2        WRITE ENABLE; SIL-2       
| JP3        JUMPER      ; SIL-2       
| JP4        JUMPER      ; SIL-2       
| JP5        JUMPER      ; SIL-2       
| JP6        JUMPER      ; SIL-2       
| JP7        JUMPER      ; SIL-2       
| JP8        ROM ENABLE  ; SIL-2       
| JP9        WRITE ENABLE; SIL-2       
| JP10       JUMPER      ; SIL-2       
| JP11       JUMPER      ; SIL-2       
| JP12       JUMPER      ; SIL-2       
| JP13       JUMPER      ; SIL-2       
| K9         CONN_3      ; SIL-3       
| P1         CONN_1      ; 1pin        
| P2         CONN_20X2   ; PIN_ARRAY_20X2
| P3         CONN_3X2    ; pin_array_3x2
| P4         CONN_1      ; 1pin        
| P5         CONN_5X2    ; PIN_ARRAY_5x2
| P6         CONN_25X2   ; PIN_ARRAY_30X2
| P11        CONN_5X2    ; PIN_ARRAY_5x2
| P16        CONN_3X2    ; pin_array_3x2
| P17        CONN_5X2    ; PIN_ARRAY_5x2
| P18        CONN_20X2   ; PIN_ARRAY_20X2
| Q1         NPN         ; TO92-INVERT 
| R1         5600        ; R3          
| R2         560         ; R3          
| R3         4700        ; R3          
| R4         4700        ; R3          
| RR1        1000        ; SIL-6       
| RR2        10K         ; r_pack9     
| RR4        10K         ; r_pack9     
| U1         74LS688     ; 20dip300    
| U2         DP8473V     ; PLCC52      
| U3         74LS688     ; 20dip300    
| U4         AM29F040J   ; 32dip600    
| U6         74LS688     ; 20dip300    
| U9         74LS688     ; 20dip300    
| U10        2864        ; 28dip600    
| U16        PC8477B     ; PLCC68      
| U17        74LS273     ; 20dip300    
| X1         CRYSTAL     ; HC-18UV     
| X2         CRYSTAL     ; HC-18UV     
#End Cmp

#Cmp ( order = Value )
| BUSPC        BUS1      ; BUS_PC      
| 47uF         C0        ; C1V7        
| 0.012 uF     C2C-1     ; C1          
| 0.015 uF     C2B-1     ; C1          
| 0.033 uF     C2A-1     ; C1          
| 4.7 nF       C23       ; C1          
| 510 pF       C1        ; C1          
| 10 pF        C12       ; C1          
| 10 pF        C13       ; C1          
| 10 pF        C14       ; C1          
| 10 pF        C15       ; C1          
| 1000 pF      C21       ; C1          
| .1uF         C2        ; C2          
| .1uF         C3        ; C2          
| .1uF         C4        ; C2          
| .1uF         C5        ; C2          
| .1uF         C6        ; C2          
| .1uF         C7        ; C2          
| .1uF         C8        ; C2          
| .1uF         C9        ; C2          
| .1uF         C10       ; C2          
| .1uF         C11       ; C2          
| .1uF         C16       ; C2          
| .1uF         C17       ; C2          
| .1uF         C18       ; C2          
| .1uF         C19       ; C2          
| .1uF         C20       ; C2          
| .1uF         C22       ; C2          
| DB37         J1        ; DB37FC      
| ROM ENABLE   JP1       ; SIL-2       
| WRITE ENABLE JP2       ; SIL-2       
| JUMPER       JP3       ; SIL-2       
| JUMPER       JP4       ; SIL-2       
| JUMPER       JP5       ; SIL-2       
| JUMPER       JP6       ; SIL-2       
| JUMPER       JP7       ; SIL-2       
| ROM ENABLE   JP8       ; SIL-2       
| WRITE ENABLE JP9       ; SIL-2       
| JUMPER       JP10      ; SIL-2       
| JUMPER       JP11      ; SIL-2       
| JUMPER       JP12      ; SIL-2       
| JUMPER       JP13      ; SIL-2       
| CONN_3       K9        ; SIL-3       
| CONN_1       P1        ; 1pin        
| CONN_1       P4        ; 1pin        
| CONN_20X2    P2        ; PIN_ARRAY_20X2
| CONN_20X2    P18       ; PIN_ARRAY_20X2
| CONN_25X2    P6        ; PIN_ARRAY_30X2
| CONN_3X2     P3        ; pin_array_3x2
| CONN_3X2     P16       ; pin_array_3x2
| CONN_5X2     P5        ; PIN_ARRAY_5x2
| CONN_5X2     P11       ; PIN_ARRAY_5x2
| CONN_5X2     P17       ; PIN_ARRAY_5x2
| NPN          Q1        ; TO92-INVERT 
| 560          R2        ; R3          
| 4700         R3        ; R3          
| 4700         R4        ; R3          
| 5600         R1        ; R3          
| 1000         RR1       ; SIL-6       
| 10K          RR2       ; r_pack9     
| 10K          RR4       ; r_pack9     
| 2864         U10       ; 28dip600    
| 74LS688      U1        ; 20dip300    
| 74LS688      U3        ; 20dip300    
| 74LS688      U6        ; 20dip300    
| 74LS688      U9        ; 20dip300    
| 74LS273      U17       ; 20dip300    
| AM29F040J    U4        ; 32dip600    
| DP8473V      U2        ; PLCC52      
| PC8477B      U16       ; PLCC68      
| CRYSTAL      X1        ; HC-18UV     
| CRYSTAL      X2        ; HC-18UV     
#End Cmp

#End List
Code:
  +------------------------------------------------+
  |                                                |
  |  FOR: SECOND-REVISION PROTOTYPE XT-FDC CARD    |
  |                                                |
  +------------------------------------------------+

DESCRIPTION: Component list for the second version of the XT-FDC prototype board.

DATE OF LAST REVISION: 04MAY2013

INITIAL AUTHOR: modem7 at the Vintage Computer Forums

COMMENT: It is expected that most people will add the optional BOOT ROM component, placing Sergey's BIOS code into the ROM.

COMMENT: For the DIL IC sockets, I highly recommend the 'machined pin' ones.
         One advantage is better soldering 'take', important for people with little soldering experience.


##########################################################################################################
#  PART 1 - BASIC FDC
##########################################################################################################

                    
Qty  Designation/s       Description                                          Example source
---------------------------------------------------------------------------------------------------------------------
1    R5                  4.7 K ohm, quarter watt

2    RR1/RR6             Resistor network - SIL - pin 1 common - 6 pin - 1K   Mouser part: 652-4606X-101-1K   Bournes (maker) part: 4606X-101-102
2    RR3/RR5             Resistor network - SIL - pin 1 common - 10 pin - 1K  Mouser part: 652-4610X-101-1K   Bournes (maker) part: 4610X-101-102

1    U6                  74LS688 (e.g. SN74LS688N)                            Mouser part: 595-SN74LS688N 
4    U5/U7/U8/U11        74LS07  (e.g. SN74LS07N)                             Mouser part: 595-SN74LS07N 
1    U16                 PC8477BV-1                                           eBay item 380556123465

1    C0                  Capacitor, electrolytic, 47 uF (> 5V)                eBay item 380516793225
2    C12/C13             Capacitor, ceramic, 10 pf                            Mouser part: 581-SR151A100KAR
1    C23 [note 1]        Capacitor, ceramic, 4.7 nf                           Mouser part: 581-SR201A472KAR

11   [note 2]            Capacitor, ceramic, 0.1 uF                           eBay item 390497290180

1    X1                  Crystal 24 MHz [see note 3]                          Mouser part: 717-9B-24.000MEEJ-B    [this works on my prototype #1 card]

1    -                   IC socket - Narrow DIL - 20 pin (for U6)             "Narrow" = 0.3" width - eBay item 181052426378 [note: 24 pieces]
4    -                   IC socket - Narrow DIL - 14 pin (for U5/U7/U8/U11)   "Narrow" = 0.3" width - eBay item 160937885391 [note: 10 pieces]
1    -                   IC socket - PLCC - 68 pin  (for U16)                 eBay item 251232944425 [Note: pin type, not SMD type]

4    JP14/JP5/JP10/JP11  Jumper block - single position                       eBay item 261019628248 [cut to size as required]
2    P3/P16              Jumper block - 3 positions                           eBay item 261019628248 [cut to size as required]
1    P17                 Jumper block - 5 positions                           eBay item 261019628248 [cut to size as required]

1    P18                 34 pin header (for 5.25" floppy cable)               eBay item 270983313975



NOTE 1:
-------
   C23 is only required if an 82077AA controller chip is fitted in socket U16.

NOTE 2:
-------
   0.1 uF supporting U6 = C10
   0.1 uF supporting U7 = C24
   0.1 uF supporting U5 = C25
   0.1 uF supporting U8 = C26
   0.1 uF supporting U11 = C27
   0.1 uF supporting U16 = C3/C6/C7/C8/C9/C11

NOTE 3:
-------
   Needs to suit the requirements of the PC8477BV-1 chip.
   From the National Semiconductor PC8477BV-1 data sheet:
                 Frequency: 24 MHz
                      Mode: Parallel Resonant (preferred)
      Fundamental Mode ESR: Less than 50 ohms
         Shunt Capacitance: Less than 7 pF  (Note that shunt capacitance is not the same as load capacitance.)
      Recommended Crystals: NEL-C5480N 24 MHz, NEL-C2800N 24 MHz, SaRonix NMP240 24 MHz



##########################################################################################################
#  PART 2 - OPTIONAL FUNCTIONALITY - SECONDARY INTERNAL CONNECTOR (P2)
##########################################################################################################

PREREQUISITE: The 'Basic FDC' functionality (per part 1) is fitted.

NOTE: Used for third and fourth drive.

WARNING: Cannot be fitted if the optional 37 pin external connector (J1) is fitted.


Qty  Designation/s       Description                                     Example source
---------------------------------------------------------------------------------------------------------------------
1    P2                  34 pin header (for 5.25" floppy cable)          eBay item 270983313975
1    JP12                Jumper block - single position                  eBay item 261019628248 [cut to size as required]



##########################################################################################################
#  PART 3 - OPTIONAL FUNCTIONALITY - BOOT ROM
##########################################################################################################


Qty  Designation/s       Description                                           Example source
---------------------------------------------------------------------------------------------------------------------

1    RR2                 Resistor network - SIL - pin 1 common - 10 pin - 10K  Mouser part: 652-4610X-101-10K    Bournes (maker) part: 4610X-101-103

3    JP1/JP2/JP4         Jumper block - single position                        eBay item 261019628248 [cut to size as required]
1    P11                 Jumper block - 5 positions                            eBay item 261019628248 [cut to size as required]

1    U9                  74LS688 (e.g. SN74LS688N)                             Mouser part: 595-SN74LS688N 
1    U10                 2864                                                  Recommend Amtel AT28C64B  [note the "B" suffix] 

2    [note 1]            Capacitor, ceramic, 0.1 uF                            eBay item 390497290180

1    -                   IC socket - Narrow DIL - 20 pin (for U9)              "Narrow" = 0.3" width - eBay item 181052426378 [note: 24 pieces]
1    -                   IC socket - Wide DIL - 28 pin   (for U10)             "Wide" = 0.6" width - eBay item 200853526558 [note: 17 pieces]


NOTE 1:
-------
   0.1 uF supporting U9 = C16
   0.1 uF supporting U10 = C4




##########################################################################################################
#  PART 4 - OPTIONAL FUNCTIONALITY - ROM DRIVE
##########################################################################################################

WARNING: No software yet written to support this optional component. None currently planned.

PREREQUISITE: One of the following two items is in place:
              1. The 'Basic FDC' functionality (per part 1) is fitted; or
              2. U6, JP14, R5 (used to generate the CD_FDC signal fed to chip U1)


Qty  Designation/s       Description                                           Example source
---------------------------------------------------------------------------------------------------------------------
2    R3/R4               4.7 K ohm, quarter watt
1    RR4                 Resistor network - SIL - pin 1 common - 10 pin - 10K  Mouser part: 652-4610X-101-10K    Bournes (maker) part: 4610X-101-103

3    JP7/JP8/JP9         Jumper block - single position                        eBay item 261019628248 [cut to size as required]
1    P5                  Jumper block - 5 positions                            eBay item 261019628248 [cut to size as required]

2    U1/U3               74LS688 (e.g. SN74LS688N)                             Mouser part: 595-SN74LS688N 
1    U17                 74LS273 (e.g. SN74LS273N)                             Mouser part: 595-SN74LS273N 
1    U4                  AM29F040B  (DIL version)                              eBay item 140891844317 [note: 2 pieces]

4    [note 1]            Capacitor, ceramic, 0.1 uF                            eBay item 390497290180

3    -                   IC socket - Narrow DIL - 20 pin (for U1/U3/U17)       "Narrow" = 0.3" width - eBay item 181052426378 [note: 24 pieces]
1    -                   IC socket - Wide DIL - 32 pin   (for U4)              "Wide" = 0.6" width - eBay item 150964290385 [note: 15 pieces]

1    Q1                  Transistor, 2N3904, in TO-92 package                  eBay item 271098898259 [that eBay item is for 50 pieces]


NOTE 1:
-------
   0.1 uF supporting U1 = C18
   0.1 uF supporting U3 = C5
   0.1 uF supporting U4 = C2
   0.1 uF supporting U17 = C17




##########################################################################################################
#  PART 5 - OPTIONAL 37 PIN EXTERNAL CONNECTOR (J1)
##########################################################################################################

PREREQUISITE: The 'Basic FDC' functionality (per part 1) is fitted.

WARNING: Cannot be fitted if the optional secondary connector (P2) is fitted.

NOTE: For drives outside of the computer (drives need to be self-powered).


Qty  Designation/s       Description                                     Example source
---------------------------------------------------------------------------------------------------------------------
1    J1                  DB37 connector
1    JP13                Jumper block - single position                  eBay item 261019628248 [cut to size as required]



##########################################################################################################
#  PART 6 - OPTIONAL CONNECTOR FOR 8 INCH DRIVE
##########################################################################################################

PREREQUISITE: The 'Basic FDC' functionality (per part 1) is fitted.

WARNING: Most 8" drives that I and friends have bought have been faulty. You may need access to someone with repair skills.
WARNING: Before buying a drive, do the research on what is required to power it (voltages/amps/connectors).
WARNING: You may need to reconfigure the 8" drive (e.g. via jumpers/shunts) to get the drive to work with the XT-FDC. Ensure you have drive documentation.
WARNING: There is no guarantee that the make/model of 8" drive you have will work with the XT-FDC. Modification of drive and/or XT-FDC may be required.
WARNING: 8" drives may be either single sided or double sided. That may be important to you.
WARNING: Most 8" drives have 77 tracks, not the 80 that a 1.2M sized 5.25" drive has. Important if you are planning to treat the 8" drive as a 1.2M sized 5.25" one.


Qty  Designation/s       Description                                     Example source
---------------------------------------------------------------------------------------------------------------------
1    P6                  50 pin header (for 8" floppy cable)             eBay item 261019628248 [cut to size as required]       Note: a 'shrouded' 50-pin connector does not fit


##########################################################################################################
#  PART 7 - OPTIONAL USE OF DP8473V INSTEAD OF PC8477BV-1 (i.e. remove DP8473V from socket U16 and place a DP8473V at socket U2) 
##########################################################################################################

Qty  Designation/s       Description                                     Example source
---------------------------------------------------------------------------------------------------------------------
1    C1                  Capacitor, 510 pF                               Mouser part: 581-SR205A511JAR
4    C14/C15             Capacitor, 10 pF                                Mouser part: 581-SR151A100KAR
1    C21                 Capacitor, 1000 pF                              Mouser part: 581-SR201A102KAR
1    C2A-1               Capacitor, 0.033 uF      
1    C2B-1               Capacitor, 0.015 uF         
1    C2C-1               Capacitor, 0.012 uF        

3    [note 1]            Capacitor, ceramic, 0.1 uF                            eBay item 390497290180

1    X2                  Crystal 24 MHz                                  Mouser part: 717-9B-24.000MEEJ-B    [this works on my prototype #1 card]

2    JP3/JP6             Jumper block - single position                  eBay item 261019628248 [cut to size as required]

1    R1                  5.6 K ohm, quarter watt
1    R2                  560 ohm, quarter watt


NOTE 1:
-------
   0.1 uF supporting U2 = C19/C20/C22


[end of document]