486DLC >>> 486DX PCB Design Updates
As I have gotten my 386 DX upper and lower motherboard PCBs working -- at least to the point of validating much of the design -- I am now...
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rehsd
Oct 8, 20231 min read
386 DX - EATX Build
Picking up from 80386 DX Build (rehsdonline.com), I am transitioning my 386 DX build to an EATX form factor, incorporating changes up to...
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rehsd
Jul 8, 20234 min read
386SX Upgrade / 386DX - Glue Logic, Bus Control PALs, GALs, PLDs, ...
For my 286 to 386SX upgrade interposer PCB, I need to implement logic for S0# and S1# (along with a few other signals). For my 386DX...
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rehsd
Jun 19, 20232 min read
80386 DX Build
While I continue to build out my 286 (386 SX) system, I thought I would start learning more about the 80386 DX. I am hoping to have a...
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rehsd
Jun 15, 20232 min read
386SX Upgrade
I'm looking into a 386SX upgrade for my 286 build. The Intel 386 Hardware Reference Manual includes the following schematic for...
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rehsd
Jun 13, 20232 min read
Accessing More RAM
I am researching how to add additional RAM to my 286 build. I started by thinking about a memory expansion card for my system. That has...
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rehsd
Jun 12, 20231 min read
FreeDOS Running. Lots More Work Needed.
I now have FreeDOS running on my 286 build. In this running post, I'll add information about incremental updates I am doing. In the...
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rehsd
Jun 5, 20231 min read
80286 System Roadmap (updated June 2023)
Back in January of this year, I posted a list of potential roadmap items for my 26 build. See 80286 System Roadmap (rehsdonline.com). As...
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rehsd
May 4, 20235 min read
Troubleshooting FreeDOS Boot on my 286 System - Hangs on execrh() Call in Kernel
As I continue to work towards getting FreeDOS running on my 286 homebrew build, I am encountering a new issue. During boot, the FreeDOS...
185 views2 comments
rehsd
Apr 30, 20233 min read
Troubleshooting CPU Flags Register Between BIOS and FreeDOS
I am running into an issue getting expected CPU flags register values back from interrupt calls made in FreeDOS to my BIOS on my 286...
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rehsd
Apr 17, 20235 min read
FreeDOS Development Environment
In this post, I will share a bit about the development environment I am using to build FreeDOS (and possibly other DOS applications). I...
173 views2 comments
rehsd
Apr 16, 20233 min read
Booting FreeDOS
At this stage of my homebrew 286 system build, I have an IDE interface to a compact flash (CF) card. I have begun implementing disk...
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rehsd
Apr 14, 20231 min read
IDE Interface
I am currently working to see if I can boot to an IDE storage device (specifically, a CF Card) and get FreeDOS's kernel loaded. I'll use...
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rehsd
Apr 2, 20231 min read
286 Build - Six Months In
I am nearly six months into my 286 project. While I started on breadboards, I am now at a nice stage where I have an ATX form-factor...
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rehsd
Mar 10, 20231 min read
Interrupts and More Interrupts
I am starting to implement support for additional interrupts on my 286 system. This includes BIOS interrupts and DOS interrupts. Relevant...
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rehsd
Feb 24, 20235 min read
Using C/C++ with my 286
Up to this point, all code running on my 286 system has been x86 assembly (real mode). I am hoping to learn how to compile C or C++ code...
184 views3 comments
rehsd
Feb 20, 20232 min read
286: Onboard ROM Updates
A helpful feature that I am looking to add to my 286 system is onboard flash ROM updates, where I do not need to remove the flash ROMs to...
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rehsd
Feb 17, 20231 min read
Sound Card for my 286 System
For my sound card, I plan to leverage previous work that I did for my 65816 system build. I will refactor the sound card to support my...
2,221 views0 comments
rehsd
Feb 15, 20232 min read
Mouse for my 80286 System (SPI to PS/2)
My 286 system does not have built-in mouse support (yet). I have been experimenting with a few options. Back on my 6502 system, I added...
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rehsd
Jan 25, 20233 min read
80286 System Roadmap
Last October (2022), I started my learning journey to develop a 286 system. See Start to an 80286 System. As of this writing, I have a...
218 views3 comments
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