Difference between revisions of "EXDOS by pear"

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===Expansion bridge===
 
===Expansion bridge===
 
[[File:EXDOSv21EXP_front.jpg|thumb|300px|EXDOS card v2.1 with expansion bridge]]
 
[[File:EXDOSv21EXP_front.jpg|thumb|300px|EXDOS card v2.1 with expansion bridge]]
 +
It allows you to connect e.g. the ZX Spectrum emulator.
 
[[File:EXDOSv21EXP_back.jpg|thumb|300px|EXDOS card v2.1 with expansion bridge]]
 
[[File:EXDOSv21EXP_back.jpg|thumb|300px|EXDOS card v2.1 with expansion bridge]]
It allows you to connect e.g. the ZX Spectrum emulator.
 
  
 
Scheme
 
Scheme

Revision as of 17:05, 1 September 2020

EXDOS card (compact version)

Brief information

It is a clone card EXDOS. Compact version designed by pear. It includes the Bus Bridge on-board.

EXDOS v2.0 Compact

EXDOS card v2.0 Compact

Refreshed EXDOS project.
It is more compact, more configurable and more compatible with newer floppy disk drives.

Futures

  • power switch with two color LED,
  • provides power for two drives (only +5V for 3,5" drives),
  • two modes of connect floppy drives - XT or AT style,
  • PC full compatible floppy drive connector,
  • possibility of powering the Enterprise from one common power supply,
  • possibility to change the order of A/B-B/A drives by jumpers,
  • support for many types of memory chip, the possibility of using the full address space of the card (256K).

Configuration

Jumper J9 (PWR in version 2) near a power socket:

  • Short: the card and the EP powered with a common power supply connected to the card,
  • Open: the card and the computer powered with separate power supplies.
If you use two separate power supplies, the jumper must be removed !
Do not connect the interface to the computer when the power is on !
The original Enterprises power supply does not have enough power to both the computer and the card, if the card powering drive(s) !
 Only if you use floppy unit with own PSU then possible use original PSU for the computer and the card.

If you want to use a single, common AC adapter should provide 9V voltage and current of about 3 - 4A.
In the case of the power supply connected direct to the card's polarity can be any (the card has a diode bridge).

When connecting the original Enterprise drive and 5.25 "drives, an additional 12V power supply is required.

Modes of floppy drives connection

XT Up to 4 drives can be connected (straight cable, drive setup by jumpers)
AT Up to 2 drives can be connected (twisted cable, fixed DS1 drives)

In both modes, for proper operation, DD or HD floppy drives with a DD/HD switch are required.
Some new HD drives aren't has a switch by factory and do not support DD disks.

A/B-B/A switch

AB standard order DS0=A, DS1=B
BA reverse order DS0=B, DS1=A

240B jumpers

The chip 240B is optional. It is only needed in two situations:

  • if you want to connect legacy Enterprise drive,
  • there are connect more than 2 floppy drives.

Use only in XT mode. Do not short these jumpers in AT mode !

Label Purpose
DCR Disk Change Reset can be used with some legacy drives, it is default disabled in EXDOS sw.
InUse can be used with some legacy drives, it is not used by EXDOS sw.
Sel3 select drive D
Sel2 select drive C

Memory type select

Into the memory socket can mount (probably) any EPROM, EEPROM, Flash ROM or even RAM memory (if EXDOS ROM is already in the SD Card Reader for example).
Use more ROM capacity than 32KB (EXDOS + additional ROMs) need to use Zozosoft's memory test which is included in EXOS 2.2+ (computer onboard ROM needed to be upgraded) or cartridge version also available (it is default installed in SD Card Reader ROM).
Original EXOS memory test only detect the first ROM program.

Pin assignment
empty A15 pin 31 /WR pin 31 0 pin 30 A17
Vcc pin 3 A14 pin 29 1 pin 1 Vcc pin 1

For chips with a capacity greater than 256KB, only the first part of address space will be used.

Example settings
Type Symbol Capacity Jumpers setting
EPROM 27C128 16 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C256 32 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C512 64 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C010 128 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C020 256 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EEPROM 28C256 32 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EEPROM W27E040 512 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F010 128 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F020 256 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F040 512 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM 62256 32 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM 628128 128 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM AS6C2008 256 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM AS6C4008 512 KB   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1

3D housing

EXDOS card housing (for v2.0 version only)

Ep128exdos.jpg

EXDOS v2.1 addendum

In the last version, the following are modified:

  • Improved EXP handling
  • Added A18 into memory config jumpers
Pin assignment
empty A15 pin 31 /WR pin 31 A18 pin 30 A17
Vcc pin 3 A14 pin 29 1 pin 1 Vcc pin 1
  • Added J1 connector ability to use as an expansion bridge

Expansion bridge

EXDOS card v2.1 with expansion bridge

It allows you to connect e.g. the ZX Spectrum emulator.

EXDOS card v2.1 with expansion bridge

Scheme

Expand scheme.jpg

PCB

Expand pcb.jpg

Documentation

User manual

Original EXDOS documentation

Scheme

EXDOS scheme.jpg

PCB

EXDOS pcb.jpg

Bill of materials (BOM)

RefDes Name Value
+12V TESTPOINT
PWR HDR-1x2 red
EXP HDR-1x2
DrvA HDR-1x3
DrvB HDR-1x3
MOT_A HDR-1x3 Cable mode
SEL_A HDR-1x3 Cable mode
CFG HDR-2x4 Legacy drive config
J2 HDR-2x8 Memory config
J1 2x33 Edge connector
J1A 2x32 Expansion port
J1B 1x2 +5V for Expansion port
PWS 4840-2201 Power
SW1 1x2 Power switch
J7 HDR-2x17 Floppy drives connector
J8 Floppy drives power
C1 CAP100 470 nF
C2 CAP100 470 nF
C3 CAP100 47 nF
C4 CAP100 47 nF
C5 CAP100 47 nF
C6 CAP100 47 nF
C7 CAP100 47 nF
C8 CAP100 47 nF
C101 CAP200RP 470 µF / 25 V
C102 CAP100 100 nF
C103 CAP100 100 nF
C104 CAP200RP 1000 µF / 10 V
D1 SR540 5 A Schottky diode
D2 SR540 5 A Schottky diode
D3 SR540 5 A Schottky diode
D4 SR540 5 A Schottky diode
D101 1N5822 3 A Schottky diode
LED red & green
L1 DE_1207 33 µH @ 3.2 A
Q1 BC337
Q2 BC337
Q3 BC337
R1 RES100 1,5 kΩ
R2 RES100 47 kΩ
R3 RES100 10 kΩ
R4 RES100 1 kΩ
R5 RES100 1,5 kΩ
R6 RES100 1,5 kΩ
R7 RES100 1,5 kΩ
R8 RES100 1,5 kΩ
R9 RES100 10 kΩ
U101 LM2596S-5.0
FDC WD1772 VL1772
GAL GAL22V10
Memory see description
240A 74LS240
240B 74LS240 optional, see description
244 74LS244
245 74LS245
273 74LS273

PLD equations

/* *************** INPUT PINS *********************/
PIN 1   = A20     ; /* A20 */ 
PIN 2   = A19     ; /* A19 */
PIN 3   = A18     ; /* A18 */ 
PIN 4   = A7      ; /* A7 */ 
PIN 5   = A6      ; /* A6 */ 
PIN 6   = A5      ; /* A5 */
PIN 7   = A4      ; /* A4 */ 
PIN 8   = A3      ; /* A3 */ 
PIN 9   = A2      ; /* A2 */ 
PIN 10  = A1      ; /* A1 */ 
PIN 11  = !IORQ   ; /* IORQ */ 
PIN 13  = !WR     ; /* WR */ 
PIN 14  = !RD     ; /* RD */ 
PIN 15  = !MREQ   ; /* MREQ */ 
PIN 21  = A21     ; /* A21 */ 

/* *************** OUTPUT PINS *********************/
PIN 16  = !WDCE   ; /* enable WD1772 */ 
PIN 17  = !RAMCS  ; /* enable RAM */ 
PIN 18  = !RDE    ; /* read from 244A */ 
PIN 19  = !RDB    ; /* buffered RD */ 
PIN 20  = !WRE    ; /* write to LS273 */ 
PIN 22  = !EXP    ; /* to Enterprise */ 
PIN 23  = !DE     ; /* enable LS245 */

/* *** RDB *** */
RDB     = RD;

/* *** ROMCE *** */
RAMCS   = MREQ & (RD # WR) & A19 & !A20 & !A21;

/* *** IOCE *** */
IOCE    = IORQ & (RD # WR) & A4 & !A5 & !A6 & !A7;

/* *** DE *** */
DE      = ROMCE $ IOCE;

/* *** WDCE *** */
WDCE    = IOCE & !A3;

/* *** EXP *** */
EXP     = DE;

/* *** WRE *** */
WRE     = WR & IOCE & A3;

/* *** RDE *** */
RDE     = RD & IOCE & A3;

/* end */