darry wrote on 2022-11-02, 22:33:
Jo22 wrote on 2022-11-02, 22:26:Not yet. Maybe the community will create something like this ?
It's more likely than a replica of the "woodgrain 386", hah. 😁 […]
Show full quote
dr.zeissler wrote on 2022-11-02, 21:43:
Would be nice if such a MPU401 card had a OPL2/3 onboard but such cards do not exist.
Not yet. Maybe the community will create something like this ?
It's more likely than a replica of the "woodgrain 386", hah. 😁
FaWr3O9agAADhlZ.jpg
Source: https://hackaday.com/2022/11/01/dana-sibera-c … hat-dont-exist/
HanJammer wrote on 2019-12-03, 14:06:
I know about SoftMPU but it requires virtual mode which is available on 386-up making it virtually useless for my purpose.
In theory.. It's possible to give an 80286 system this ability by using external logic.
I remember that PC-MOS/386, an MS-DOS compatible multi-tasking OS, supported an external MMU
that could be installed between the 80286 and its mainboard.
With the MMU in place, the 80286 could support memory management and multitasking similar to an 80386.
In addition to the soon to be released Orpheus II (which I meComputersin my previous post), the AWE64 Legacy has both a HardMPU and an OPL3 .
AFAICR, an external MMU for 286 CPUs did exist as a commercial products I think the manufacturer was "ALL Computer" and was named "ALL Chargecard". I am not 100% on the actual names.
You're right, it exists! 🙂👍
https://www.youtube.com/watch?v=xgMIbo6QoM4
HanJammer wrote on 2019-12-03, 14:06:
It was not compatible with 386 MMU functionality, again AFAICR.
Well, it surely wasn't instruction compatible.
Otherwise it would have had interfered with the 286's own 286 MMU, which the 386 MMU is based upon.
However, it had a driver diskette with a LIM 4 compatible EMS driver, at least.
So DOS compatibility was provided.
And if it was related to the card mentioned in PC-MOS documentation,
it might have been able to do more than just providing Expanded Memory.
If would have had the ability to trap interrupts and memory writes/reads.
Which would allow us to add support for it into SoftMPU.
That would be impressive. If only we had access to the information about the MMU chip!
An FPGA could be used to mimic its behavior.
Let's think about it, this would breath new life into the 286 platform!
There are so many new Open Source projects!
PC-MOS/386 has its source code at Github, PC GEOS became FreeGEOS, there's OpenGEM..
Such a little interposer card could bring homebrewing to a new level!
Sute, someone could also claim that a 386 upgrade board could do the same.
But then we're dealing with V86 again, and all it's compatibility issues.
That ALL Chargecard board's MMU could maybe co-exist with a 386SX chip, even.
If that's the case, it could brighten up the days for 386 owners, too!
Imagine, an external MMU for 80386/80486 motherboards.
That would be awesome. QEMM like memory managers that don't need V86. Yahoooo! 😁
Edit: Or let me pput it this way:
If that MMU is able to listen/write to any memory address, it could talk/listen. to the 80286!
The 80286 writes data into a "void" were no physical hardware existes, but the MMU is listening to. Or vice-versa.
Things like a virtual COM port driver will become possible then.
A game writes MPU-401 data to port 330h, where the ALL Chargecard MMU is listening.
The MMU then will transfer the data to SoftMPU, which processes the data and sends it to port 300h, were the sound card with the dumb MPU-401 is located.
All this in Real-Mode! As if we're using a MIDIQuest card.
"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel
//My video channel//
