It‘s done. Mission complete. Finished!
Thank you all so much for your long-term help!! Especially to mkarcher with some detailed guidance in the background and zyga and also rasz_pl.
At the end I desoldered the Busosc Pin. What happened then:
System booted but could not boot from hdd nor fdd. At the end I had to insert some waitstates for 16BIT IO and 8Bit IO. Then all worked. Even win95 booted so it should be stable.
DMA speed = ISA speed at 13,75MHz (27,5/2).
- 3DBench from 9,9 to 10,1 [+2%]
- Thruput Average CPU from 7,17 to 7,17 [+0%]
- Thruput Average Video from 6,194 to 8,220 (!!!) [+32,7%]
- Vidspeed L from 7004/3137 to 10959/4181 (!!!) [+56% / +32%]
- Wintach Win95 GDI from 6,89 to 7,72 (!!!) [+12%]
- Doom from 14,24 to 14,92 [+4,78%]
Tja at the end I am happy. Quite sure that I mostly got out the system what’s possible. Only downside is the + 1WS AND that I cannot directly compare Busosc vs IntDivider results as the ISA / DMA speed differs.
Where I am really surprised is the increase in Thruput video & vidspeed. Maybe these numbers do show the potential which cannot be executed in real world benches due to 386sx27,5 as limiting factor.
Thanks to all !!!!!!
1) VLSI SCAMP 311 / 386SX@27,5 (non-W95: stable at 30MHz) / 8MB / CL-GD5428 / LAPC-I / Fast-SCSI AHA 1542CP (...which is disappointing)
2) SIS486 / 486DX/2 66 / 32MB / TGUI9440 / SCC-1&MT32 / CT2830