EXDOS by pear
Contents
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
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 cable, drive setup by jumpers) |
---|---|
AT | Two 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
Use only in XT mode. Do not short them 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).
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.
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 |