Trashbytes wrote on 2024-05-11, 07:28:Input Output Control Hub or the South Bridge in most cases controls access to all IO systems on the Motherboard from Serial thro […]
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Input Output Control Hub or the South Bridge in most cases controls access to all IO systems on the Motherboard from Serial through to Drives, pretty sure USB along with all other Input/Output systems are part of the south bridge in newer modern systems.
In older boards USB/Firewire is controlled through one or more separate ICs, SATA too is also usually a seperate IC on older boards.
On a 386 it may mean Input Output Control Header/Hub which may mean the ICs controlling extra serial IO.
What happens when you put a jumper on that pin ? my guess is it sets the IOCH to the ready state and is for compatibility reasons.
Well, I don't know if any 486 board ever supported USB or FireWire (IEEE1394) ports. Maybe some industrial boards form late 90's do, but this is not the case.
My controller is just simple standard for its time ISA controller and works fine on 386 or 486 boards. I've soldered the missing pins on the jumper header for this IOCHREADY setting, but I don't want to try it with HDD attached until I'm not 100% sure what this means and what its purpose is 😀 I thought maybe it is short from something like "I/O channel ready", but the purpose is more important.
vstrakh wrote on 2024-05-11, 07:50:It's all about ISA bus timings and wait states. There is a default ready timeout that gives I/O devices time to perform the requ […]
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It's all about ISA bus timings and wait states. There is a default ready timeout that gives I/O devices time to perform the request.
Sometimes the device needs more time, and it can pull the CHRDY (or IOCHRDY, IOCHREADY, meaning 'I/O channel ready') signal low to indicate it needs more time, and extra wait cycles are inserted on the ISA bus as long as that signal is held low.
The opposite of the CHRDY is NOWS/0WS - the device can pull that line to signal request completion before the default ready timeout has elapsed.
Your particular card might be just fast enough to not require extra wait states to serve the requests.
Hah, without meaning to I've hit the abbreviation 😁 Thanks for this explanations!
I have to check if one of the two pins is shorted to ground.**
So, Is this setting for some older drives compatibility or what? Are this cycles chipset related or they're HDD dependent?
P.S. A simple explanation like "use IOCHREADY setting in case of..." or "don't use it in case of..." will be be appreciated, 'cause I've never had user manual for this controller.
Edit: **- I've checked this and it turned out that no ground is involved on the ISA controller's PCB.
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