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AT system without -5v
With better character handling capability, why didn't PC-98 system succeed in rest of East Asia?Cannot boot off of Compact Flash cardWhat is the oldest commercial MS-DOS program that can run on modern versions of Windows without third-party software?
I have recently built a 80386 system. Lacking any AT PSU I connected a PicoPSU using an ATX->AT power adapter. Only card connected was a gpu (Trident TVGA 9000i). System performed BIOS checkup sequence without errors and reached boot stage. I did not connect a MultiIO card so did not proceed to booting.
PicoPSU is not v.1.x of ATX standard and so does not provide any -5 Volts capability. From what I have read, -5V is needed only by ISA bus and only from those cards requiring it (5th pin of back side of card, named B05 in ISA pinout.
My question is: If I stick to ISA cards which do not need -5v (lack of B05 contact in card) do I face any other risks when resorting to an ATX->AT conversion so as to power the board?
ibm-pc isa
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
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add a comment |
I have recently built a 80386 system. Lacking any AT PSU I connected a PicoPSU using an ATX->AT power adapter. Only card connected was a gpu (Trident TVGA 9000i). System performed BIOS checkup sequence without errors and reached boot stage. I did not connect a MultiIO card so did not proceed to booting.
PicoPSU is not v.1.x of ATX standard and so does not provide any -5 Volts capability. From what I have read, -5V is needed only by ISA bus and only from those cards requiring it (5th pin of back side of card, named B05 in ISA pinout.
My question is: If I stick to ISA cards which do not need -5v (lack of B05 contact in card) do I face any other risks when resorting to an ATX->AT conversion so as to power the board?
ibm-pc isa
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I have recently built a 80386 system. Lacking any AT PSU I connected a PicoPSU using an ATX->AT power adapter. Only card connected was a gpu (Trident TVGA 9000i). System performed BIOS checkup sequence without errors and reached boot stage. I did not connect a MultiIO card so did not proceed to booting.
PicoPSU is not v.1.x of ATX standard and so does not provide any -5 Volts capability. From what I have read, -5V is needed only by ISA bus and only from those cards requiring it (5th pin of back side of card, named B05 in ISA pinout.
My question is: If I stick to ISA cards which do not need -5v (lack of B05 contact in card) do I face any other risks when resorting to an ATX->AT conversion so as to power the board?
ibm-pc isa
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I have recently built a 80386 system. Lacking any AT PSU I connected a PicoPSU using an ATX->AT power adapter. Only card connected was a gpu (Trident TVGA 9000i). System performed BIOS checkup sequence without errors and reached boot stage. I did not connect a MultiIO card so did not proceed to booting.
PicoPSU is not v.1.x of ATX standard and so does not provide any -5 Volts capability. From what I have read, -5V is needed only by ISA bus and only from those cards requiring it (5th pin of back side of card, named B05 in ISA pinout.
My question is: If I stick to ISA cards which do not need -5v (lack of B05 contact in card) do I face any other risks when resorting to an ATX->AT conversion so as to power the board?
ibm-pc isa
ibm-pc isa
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
edited Jun 23 at 8:19
dirkt
9,9141 gold badge26 silver badges48 bronze badges
9,9141 gold badge26 silver badges48 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
asked Jun 23 at 7:29
padawanpadawan
383 bronze badges
383 bronze badges
New contributor
padawan is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
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Check out our Code of Conduct.
add a comment |
add a comment |
1 Answer
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If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3V output, so normal ATX supplies may not work properly of there is no load on 3.3V as AT does not use 3.3V supply. The PicoPSU may work without 3.3V load just fine. And there are adapters to make -5V from -12V if necessary.
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
|
show 1 more comment
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If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3V output, so normal ATX supplies may not work properly of there is no load on 3.3V as AT does not use 3.3V supply. The PicoPSU may work without 3.3V load just fine. And there are adapters to make -5V from -12V if necessary.
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
|
show 1 more comment
If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3V output, so normal ATX supplies may not work properly of there is no load on 3.3V as AT does not use 3.3V supply. The PicoPSU may work without 3.3V load just fine. And there are adapters to make -5V from -12V if necessary.
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
|
show 1 more comment
If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3V output, so normal ATX supplies may not work properly of there is no load on 3.3V as AT does not use 3.3V supply. The PicoPSU may work without 3.3V load just fine. And there are adapters to make -5V from -12V if necessary.
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
If it works and the voltages are within tolerance then it should be OK to use it. The only thing that might affect things is that normal ATX supplies may regulate voltages according to 3.3V output, so normal ATX supplies may not work properly of there is no load on 3.3V as AT does not use 3.3V supply. The PicoPSU may work without 3.3V load just fine. And there are adapters to make -5V from -12V if necessary.
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
answered Jun 23 at 8:04
JustmeJustme
1,1593 silver badges10 bronze badges
1,1593 silver badges10 bronze badges
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
|
show 1 more comment
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
I think even a small load like a LED would solve the 3.3V problem (just to close the regulation loop of PSU)... anyway -12V to -5V is really just few diodes in serial or one zener diode taking 7V from the 12V ... not even a resistor is needed ... there are 6V9 zener diodes out there ...
– Spektre
Jun 23 at 9:40
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
That is very dubious to drop voltage with just diodes or zeners. Usually a 7905 linear regulator is used. Or a charge pump to make the negative voltages from positive.
– Justme
Jun 23 at 10:39
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
I know but one or few diodes can fit directly onto/into a cable (just before the connector with very small effort or change in the HW) and -5V is usually used just for a reference so its very low power anyway ...
– Spektre
Jun 23 at 12:14
3
3
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
It is mainly used only by a few sound cards. And if it is used, it is used as the negative power supply for audio op-amps, not as a reference.
– Justme
Jun 23 at 14:24
1
1
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
Dropping voltage with diodes here is ridiculous. You can get a proper buck converter on Amazon for a few bucks (pun intended), or on aliexpress for a few pennies.
– R..
Jun 23 at 22:06
|
show 1 more comment
padawan is a new contributor. Be nice, and check out our Code of Conduct.
padawan is a new contributor. Be nice, and check out our Code of Conduct.
padawan is a new contributor. Be nice, and check out our Code of Conduct.
padawan is a new contributor. Be nice, and check out our Code of Conduct.
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