Thursday, November 12, 2037

About the projects // О проектах

68k project (under construction)
Read by tag:68kavr

Z80 project (considered complete, but will be updated sometimes)
Idea here
Read about Searle Grant's SBC SD interface (and generally CP/M SD implementation) by tag sgsbcsd

Note, that the early records were imported from Livejournal and should be edited by me sometimes later (I bet that will never happen).
Also, some early records may contain some weird letters - that's russian, but it is always translated, do not be afraid.
Also, sometimes I write about some unrelated (even PC!) but weird hardware, some unrelated but weird network technologies, and some weird things. May be even I'll attempt to write a big post about butterflies. If I ever got interested in butterflies.

Tuesday, December 19, 2017

RCA / CDP1802 project with the same ideas

Here. Well, one more project to boot a CPU from ATMega8. And today that's a 1802!

Wednesday, November 15, 2017

Tiny AVR based project to reset Z80 (or any other CPU) by a serial line

For the modern DIY computers that's normal to be connected by serial port. And in most of cases that's the only way how the communication is made.

But all that Z80 and MC68000 CPUs sometimes HANGS! (Well, do not blame them, blame yourself for a buggy code). But no matter - we have to reset them. And to do that remotely.

So this tiny tool does that: it uses 2 lines from your DIY computer - the reset line and TTL-level RX line of the console. To initiate /RESET, just send break.

You need ATTINY2313, avr-gcc compiler, mm...avrdude and (probably) to edit 2 lines of code in main.c:
#define F_CPU 12000000L
#define BAUD 57600

First is the freq of yours' quarts, the second is the baudrate of your console.

And all that work for me.

Get it all here

Tuesday, June 13, 2017

Restoring root password in LevelOne GSW-2472TGX switch not trivial. More, there is no known way.
So this is the original and the only known method invented by me:
Take off the case. (The CPU is VIA6526A; just FYI, that will not help us). Plug serial @ 9600 8n1, plug power. Wait for login prompt.
Then, hot-plug-off the only chip you can plug off - that's 2408 serial eeprom. Yes, really, plug it off! The switch is useless if you cannot restore root password, so nothing bad can happen, except of electric shock!
Then, login as root/root. It will think a little, but allow you to log in.
Next, hot-plug 2408 chip again and change the password.
You are done. My congrats!

Friday, March 17, 2017

Sun 150 and semi-dead nvram

Well, it happened to me: while Sun blade said some reasonable Mac and SystemID, they did not match.
The following helped:
Take Ultra 10 (you own Ultra 10, don't you?), power it up, then hotswap nvram chip and use mkp with system id 0x83.
It will complain "nvram is wrong", but auto-boot. Then put the chip back to SB100.
The problem came when I plugged VGA display to SB, improperly grounded.
UPD: the nvram died permanently. So I had to break the chip and install CR2032 to feed it.

Saturday, August 20, 2016

Installing Slackware 14.2 on Toshiba ac 100 with mainline kernel

The tasks:
  • - switch to GPT partitioning and partition the EMMC
  • - compile kernel, make it bootable
  • - take slackware root
Before stating, keep at mind that internal EMMC is reffered as /dev/mmcblk0p, but if you plug SD card before loading... well, too early, it will became /dev/mmcblk0p, not 1p, as you can expect. This makes AC100 to boot at least root fs from SD card.
First, follow ARCH linux installation guide. The easiest way to compile kernel is to do it on some other ARM computer - saying, on Orange PI (Banana or Raspberry, if you prefer). Stop following this guide until you have only /boot (and /lib with kernel module , and /etc/ with fstab) on your's EMMC card.
Then take Slackware arm root from here and copy it to EMMC (without boot and preserving /etc/fstab and /lib/kernel modules). Check twice you have a correct fstab (first, root fs and after you boot it - tmpfs and udev)
Next, take a full slackware-arm to sd card, boot the system, plug sd card, mount it, check you have udev running and.. you know what to do with slackware.

Friday, August 5, 2016

GammuTK - very basic TK gui for sending SMSes via GAMMU

Well, that does exactly what it does, and nothing more: it provides simple TCL/TK gui for sending [long][i18n] SMSes. It takes CSV file with phones, lets you edit the SMS and sends to selected numbers. Nothing more. Grab it here.