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Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (if your only other option is L2 at 3-2-2-2)

The PCI speed is 25 MHz because, as you posted in another thread, the 2/3 output is is misshapen, as if it has a duty cycle that is not 50%. Exactly. Maybe I can find a PCI graphics card that doesn't care about the wrong duty cycle, and use the 2/3 divider. Could the PCI clock be provided in some …

Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (if your only other option is L2 at 3-2-2-2)

Got the A19 line soldered back in, and fixed it with super glue as strain relief this time. The system still works with at 3-1-1-1 at FSB50. But I got one step faster! If I disable "early cache write mode" in the CMOS setup, the performance at a given cache timing setting does not drop (at least …

Re: CL GD5422/20 vs 8900c on 386

The 5420 is 16 bit memory interface, the 5422 can do 32 bit. It's possible the 5420 may gain something from banked 16 bit Well, the data book is confusing there. At some locations, it claims "5420 has a 16-bit memory interface". At other locations, it limits this claim to the "A" revision. The …

Re: CL GD5422/20 vs 8900c on 386

Both Cirrus chips hit the ISA speed limit. [...] BTW, note that both your Cirrus cards only have 512 KB of RAM - it doesn't make sense! They are well worth upgrading to full 1 MB. Using the Cirrus cards with only 512KB of RAM halves their memory bandwidth. I'm unsure whether they still manage to …

Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (if your only other option is L2 at 3-2-2-2)

I had clicked "Download Zip" from this page, but it did not contain JLCPCB gerbers. This is the zip I had been uploading to JLCPCB which didn't work. Shown here: Github_screenshot_1.png I'm sorry for that misunderstanding. I tried to avoid that by directly linking the v1.1 release page in my last …

Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (if your only other option is L2 at 3-2-2-2)

When you uploaded these zip files (v1.0 or v1.1) to JLCPCB, did you see "Detected 0 layer" and notice that Gerber Viewer cannot open? Normally, the website detects the correct layer and Gerber Viewer works. Oh, that's strange. I tried the automation of the Gerber generation on my system before …

Re: 486 board with UMC 8881E/8886B: The winner is: EDO without L2 (if your only other option is L2 at 3-2-2-2)

Looking forward to this... I just finished https://github.com/karcherm/mb8433-uud-cache-pcb/releases/tag/v1.1 - I hope this suits your requirements. This comes with absolutely *no* *warranty*, as I only tested a prototype of v1.0, but as the current version still passes the built-in checks in KiCad …

Re: Quadram EGAVGA - how to get it into VGA mode?

Hires "mode 12": Quadram_EGAVGA_hires_hsync.png What you see here is likely cross-talk from the video signal, while the text mode is probably taken with a mostly black screen. The EGA hi-res mode is known for squeezing the horizontal timing as much as possible, i.e. display up to the latest …

Re: SB16 Vibra +1 tone

I'm wondering if your mobo/BIOS settings are using a too high ISA clock. The ISA clock (CLK) and the 14.318 oscillator pin (OSC) on the ISA bus are two different pins. ISA clock adjustment is not supposed to have any influence on the OSC pin. On many modern boards, OSC is driven directly from the …

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