Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-16, 11:48
Tiido wrote on 2022-06-16, 07:57: It has been great reading these posts, thänk you very much for all this work ~ You are welcome. Greetings from Holland, Jan
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-16, 10:02
Sphere478 wrote on 2022-06-15, 21:31: Sweet! Suggest uploading txt files as quoted code so if the attachments ever go dark wayback machine will have it Sphere478, thanks for the tip. I've also thought about safekeeping and I will upload the completed guide as pdf document later on. Jan
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-15, 20:46
Patching for the Am5x86 Okay, now we need to decide what needs to be changed to support the Am5x86 CPU in the 1995 BIOS. Because the BIOS_uP_ID is used in multiple places during POST to make decisions depending on the CPU model, the most effective way to add Am5x86 support to a 1995 BIOS is to let …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-15, 20:37
Result of Method 1, 2, and 3 Each item of the CPUID tables, the Cx_DIR0 table, and the Reset_ID table contains two corresponding CMOS_3D_uP_ID and CMOS_3F_data bytes. When a match is found, these bytes are stored in CMOS registers 3Dh and 3Fh respectively, just as in the 1994 BIOS. Bits 6-0 in the …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-15, 20:19
Method 2 - Cyrix detection Another change in the 1995 Award BIOS is the way Cyrix CPUs are detected. Instead of hard-coded instructions, a table with DIR0 (Device Identification Register 0) values is now used. Device Identification Register 0 is present on all Cyrix design CPUs, except the Cx486S …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-15, 20:05
CPU detection We now jump back further into the BIOS where the actual CPU detection is done and where the uP_ID is generated. Unlike the single Reset_ID table detection method in earlier BIOS versions, these March 1995 and later BIOSes now use 3 different methods for CPU detection, with separate …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-15, 20:04
#Part 5 – What to patch in an uncompressed Award BIOS – cont’d In this episode, I will focus on the changed CPU detection in the 1995 BIOS and how that influences the patches you can make to get better Am5x86-133 support in these 486 Award BIOSes. Between December 1994 and February 1995, support …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-06-03, 20:23
Endianness Before embarking on the next episode of this DIY BIOS Modding guide, I need to correct an omission and explain about endianness or, as Wikipedia defines it, “the order or sequence of bytes of a word of digital data in computer memory”. A comprehensive article about endianness can be …
Re: DFI G486-VVP Motherboard manual... creating
Posted on 2022-06-02, 19:18
I agree with your “cheap office workhorse” assessment, using older but proven technology. ;) And using a VT82C505 VLB-PCI bridge chip to implement PCI slots, creating a versatile VLB/PCI board but with a lower PCI performance than when using a dedicated PCI chipset like on your MB-8433UUD-A. OK, you …
Re: DFI G486-VVP Motherboard manual... creating
Posted on 2022-05-30, 15:00
Hi maksymke, Welcome to the Vogons community. That’s an interesting early 486 VLB board with PCI slots. :) Did you check the actual Am486DX4-100 speed with a DOS tool? The early to mid 1994 BIOSes on these boards don’t support the Am486DX4 CPU (that’s why they are detected as 80486DX2) and may …
Re: SY-5EMA+ writing cache becomes disabled
Posted on 2022-05-19, 20:15
Hi Baoran, Ik believe I know why a lot of socket 7 systems show this 512MB RAM issue. All Award socket 7 BIOSes that I've checked have a limitation in the Write-Allocate feature. So this issue is not limited to one particular chipset, but is present on all super socket 7 boards with the Award BIOS. …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-05-10, 20:51
terryfi wrote on 2022-04-03, 01:14: Thanks Jan, please take your time; meanwhile we will enjoy your future stories 😀 Hi terryfi, The patched DFI 586ITBD BIOS is ready and I send you a PM with the BIOS and a test guide. Please let us know how it works, so I can publish this BIOS on my k6plus page. 😉 …
Re: 160mhz CPU on VLB Motherboard ?
Posted on 2022-05-10, 16:40
@TheMobRules, Great to hear the modded GA-486VS BIOS works well. :) Thanks for the register 72h tweak and the J.2 BIOS! I’ve seen the 8+0 / 7+1 tag bits selection for the motherboard cache in the BIOSes of several other 486 chipsets, and understand the working of the dirty bit for Write-Back cache. …
Re: 160mhz CPU on VLB Motherboard ?
Posted on 2022-05-09, 19:17
Can you provide some details on what kind of things you tweak in order to "adapt" a SiS471 BIOS to work on a different board? I have previously used an Award BIOS from the ASUS VL/I-486SV2GX4 on an MSI MS4132G (which has an awful AMI BIOS that severely hinders RAM and cache performance) and it …
Re: 160mhz CPU on VLB Motherboard ?
Posted on 2022-05-09, 19:16
Thanks, but no rush. I don’t have an eprom programmer device anyways. I will probably just stick with the Intel 486dx4-100 which what I currently have in this motherboard. An Intel DX4-100 is a good choice for this board as well and, as Disruptor pointed out, the Rev. 8a board has support for 3.3V …
Re: 160mhz CPU on VLB Motherboard ?
Posted on 2022-05-08, 11:33
I agree that this GA-486VS Rev. 8a board is a good candidate for the Am5x86-P75 CPU. With its P24D (i486DX2WB) and DX4-100 support, it has proper hardware support for all 5V and 3.3V socket 3 CPUs. The culprit however is the BIOS. @TheMobRules, thanks for the latest official BIOS for the 486VS. I’ve …
Re: 160mhz CPU on VLB Motherboard ?
Posted on 2022-05-06, 11:33
This could work fine if your board has a SiS471 chipset. Which GA-486 VLB board do you have exactly and what is the present BIOS version? So I can check your BIOS for Am5x86 support.
Re: md-4duv-ver 2.1 Motherboard DX4-100 Unstable - DX2-66 works fine
Posted on 2022-05-02, 20:39
Thanks Jan, if you could check to see if it supports DX4 (which the motherboard I have suggests it should do) that would be great. I will sort myself out with a Compatible EEPROM so I can burn it to a chip to test. I did a detailed analysis of the 4DUV VER 3.1 BIOS and I couldn’t find any omissions …
Re: md-4duv-ver 2.1 Motherboard DX4-100 Unstable - DX2-66 works fine
Posted on 2022-04-28, 09:29
@DaveDoc1984 If you would rather try modding the original 4DUV VER 3.1 BIOS, here is a correct copy of this Award 11/17/94-UMC-498GP-2C4X6A31-00 BIOS. The BIOS dump from Ultimate Retro appears to be a dump from Shadow RAM and has checksum errors. :( If you want me to enable the hidden BIOS options …
Re: DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb
Posted on 2022-04-02, 18:53
Terryfi, thanks for the DFI 586ITBD BIOS. I've checked this mid 1998 BIOS and yes, it can be patched for: - K6-III/K6-2+/K6-III+ support - Write-Allocation support for K6-2CXT/-III/-2+/-III+ - CPU speed support above 400MHz up to 500MHz - 32GB and 64GB bugfixes for 128GiB HDD support I’ve put it on …
Page 13 of 19