Thursday, November 12, 2037

About the projects // О проектах

68k project (under construction)
Idea:here
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.

Sunday, June 10, 2018

Some more investigations on Compaq Prosignia VS

I was sure that the board has a memory hole. Nothing like that! It's highly configurable. In the Compaq Setup you can say you have Unix and even Linux installed.
However, BIOS still reports 16M. You have to tell Linux it has more (8 onboard + 4*8 in my case) - so tell Lilo
append="sim710=addr:0x8000,irq:15 mem=exactmap mem=640k@0 mem=15M@1M mem=24M@16M mem=nopentium acpi=off noisapnp"
No matter, still - one of the first thing Linux says - "I've caught NMI!". And linux ignores it. But OpenBSD does not ;-(

Wednesday, March 28, 2018

Video cards in HP 9000 computers

From time to time I get some HP 9000 video cards and plug them into my hp/ux HPPA computers.
For a long time I could not understand why they are not working: I can see them both in boot and in HP/UX, but hell, they show nothing!
The answer is simple: use at least 1260x1024x75 monitor. Really, I wasted a lot of time trying to understand why I cant run it.
And more, A4552 66501 PCI-X card at least shows something in PCI C160 computer!

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

..is 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.