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]] | ||
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Scheme | Scheme |
Revision as of 17:05, 1 September 2020
Brief information
It is a clone card EXDOS. Compact version designed by pear. It includes the Bus Bridge on-board.
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
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.
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 | 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)
EXDOS v2.1 addendum
In the last version, the following are modified:
- Improved EXP handling
- Added A18 into memory config jumpers
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
It allows you to connect e.g. the ZX Spectrum emulator.
Scheme
PCB
Documentation
User manual
Scheme
PCB
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 */