EXDOS by pear

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Revision as of 19:23, 18 May 2018 by Pear (talk | contribs) (Brief information)

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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 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).

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

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

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

Modes of drives connection

XT Up to 4 drives can be connected (straight tape, drive setup by jumpers)
AT Two drives can be connected (interlaced tape, 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

Use only in XT mode. Do not short them in AT mode !

Label Purpose
DCR Disk Change Reset used only with original EP drive
InUse used only with original EP drive
Sel3 select drive C
Sel2 select drive D

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).

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 Jumpers setting
EPROM 27C128   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C256   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C512   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C010   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EPROM 27C020   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EEPROM 28C256   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
EEPROM W27E040   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F010   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F020   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
FlashROM 29F040   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM 62256   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM 628128   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM AS6C2008   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1
RAM AS6C4008   A15 P31 /WR P31 0 P30 A17
Vcc P3 A14 P29 1 P1 Vcc P1