EXDOS by pear

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EXDOS card (compact version)

Brief information

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

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

  • Short: card and a EP powered with a common power supply connected to the card,
  • Open: card and a 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).

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

The power requirements and its configuration are the same as in the previous version of the card (see above).

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