Redford did a whole lotta work reverse engineering the BIOS code and figured out that most of the interesting stuff (password check, challenge/response for lost password) is actually done by something off the main x86 processor. We figured out that it's...
While revisiting key handler handleKeyScanCode_EE37 and back annotating scan codes into the code, I wind up with this:EE37 handleKeyScanCode_EE37: EE37 13 63 01 04 brclr bCloverKeyDown_63 1 noclover_EE3F ; true if 'clover key down' EE3B 12 61 01 C9 brset...
I have squeezed some simple instructions into a 16-byte ROM that writes 0x04 into the I/O address 0x00, and repeats (http://www.homebrew8088.com/):A: MOV AL, 04 OUT 00, AL JMP AThis is then converted into machine code (https://defuse.ca/online-x86-assembler.htm),...
In this project, instead of using a standard embedded processor and programming it to execute 3 tasks at hand (parsing HEX character stream, generating HEX character stream, and writing character stream to video RAM driving VGA), I created 3 independent...
Revisiting the RAM signature stamping knowing what I know now, I can better see what's going on and record that knowledge. The RAM stamping routine now looks like this:F723 ; stamp 'ram valid signature' on RAM page 0 and 3 F723 stampRAMsignature_F723:...
I tried a couple of other cards and found that they have different MBR formats with no header. I noted this in a previous log. There's an offset at 0x01BE that points to the MBR. My theory is this is true for "bigger" cards. I think the reason I could...
Summary:It occurred to me that it would be useful to save some configuration in a non-volatile manner. This board and this chip does not have any conventional non-volatile storage (e.g. EE or external serial EE), but there's plenty of pages of unused...
Building a CP/M System Disk To avoid rewriting the assembler codes for ccp, bdos and cbios so that they can co-exist in the same file. I can append the i8hex files and remove the "end of file markers". To make the hex file more readable I have changed...
This code is a slight update of the last one, updated:>Better Uptime Counter>LCD Shield>New Pin out Diagram>Restart Protected Calibration Details>EU and US Plug Calibrated Probe Also a quick update to the code so the calibration value will survive a...
I also wanted to sniff the communication between the micro controller and radio IC, but couldn't get the case of the remote control open. At the next opportunity I brought the Mi-Light Wi-Fi controller with me and got that open more or less easily:Inside...
While whizzing through the code trying to scrounge verified keyboard scan codes and flags, I found some some buried treasure in the form of an undocumented test routine. It's not that exciting -- it just fills the current file with some sample...
It's been nearly 2 years since my last log, and things are quite different from where I left it. I've been poking around at this project in between other projects and university, so most of these details are not recent. I found out that there has since...