After clearing all the shorts the clock still wouldn't run. Looks like I've screwed up the crystal circuit. The STM32 is providing a brute force clock for now

#homebrewcomputer #electronics

It took a few reflow attempts but this looks good now

#homebrewcomputer

It's fustrating when you get the footprint wrong, but to get the type of part wrong that's just embarasing

#homebrewcomputer

https://www.youtube.com/watch?v=rxBV3YILaaM

#HomebrewComputer #RetroComputing

I've hacked together a vbcc backend for it, so now it can run some simple C programs. This mandelbrot program only takes twice as long as my hand-written assembly version.

#homebrewcomputer #compiler #dip8

DIY GameTank Game Console Gets Upgraded Cartridge https://hackaday.com/2023/01/05/diy-gametank-game-console-gets-upgraded-cartridge/ #homebrewcomputer #Retrocomputing #flashcartridge #gameconsole #cartridge #Parts #6502

DIY GameTank Game Console Gets Upgraded Cartridge - Over the summer, you might recall seeing a homebrew 6502 game console called the G... - https://hackaday.com/2023/01/05/diy-gametank-game-console-gets-upgraded-cartridge/ #homebrewcomputer #retrocomputing #flashcartridge #gameconsole #cartridge #parts

Thinking about another discrete CPU design / #homebrewcomputer

This time I want to do the instruction decoding in logic (maybe some GALs) instead of using EEPROMs. So the instruction set should be simple and orthogonal. I'm thinking of a Harvard design with 16-bit wide instructions.

I like how the 68k ISA has three bits to specify the addressing mode, which is common across pretty much all the instructions. I might do something similar.

#ttl #cpu #retrocomputing

The Coleman Z80 is a Modern Take on a 1970s Computer https://hackaday.com/2022/12/20/the-coleman-z80-is-a-modern-take-on-a-1970s-computer/ #homebrewcomputer #Retrocomputing #computerhacks #lasercut #RC2014 #z80

The Coleman Z80 is a Modern Take on a 1970s Computer - [Joshua Coleman] likes to design his own computers. Sometimes, that means drawing ... - https://hackaday.com/2022/12/20/the-coleman-z80-is-a-modern-take-on-a-1970s-computer/ #homebrewcomputer #retrocomputing #computerhacks #lasercut #rc2014 #z80

Wonder if these GAL equations for the revised address decoding of my #homebrewcomputer are legit... 🤔​

The good news is that my GAL stock seems fine. I managed to assemble a JEDEC file for it, describing the current address decoding logic of my #homebrewcomputer, using galasm, and to successfully program it.

The bad news is that it does ... something ... but not the right thing. But I suspect that is because I haven't properly formulated the equations, which can hopefully be fixed... 😅​

Starting to think a little about how to incorporate video into my #homebrewcomputer.

I think I will sidestep a whole slew of complex timing challenges by letting the video chip have it's own RAM, and use some dual port static RAM I happen to stock. 😅​

But the tradeoff for not doing lockstep CPU/video RAM access is that I will then need to map the RAM into the existing memory map somewhere, which means messing with address decoding which currently is discrete logic. 😬​

Maybe it's time to replace the address decoding by a single GAL Would cut down the propagation delay as well... 🤔​

#electronics

Second attempt to source some #MC6847 ICs for my #homebrewcomputer.

Previous ones didn't behave as expected in the test rig, maybe these will...

#electronics

Oh yeah, and what are you gonna *do* about it?

#homebrewcomputer #mc6847 #electronics

Now that I'm tinkering with my #homebrewcomputer again (adding video and sound), I spent a little time doing a "dev shield", breaking out the various bus signals.

This should allow me to hook up the base computer with contraptions on the breadboard, and probe interactions, more easily.

Off to the fab house it goes...

#electronics

Playing around with a Motorola MC6847 Video Display Generator, considering using it in my currently headless #homebrewcomputer.

I get legit horisontal sync and field sync signals out of it, and looking at the luminance output, it seems to plausibly be doing the video framing.

However, it never outputs anything on its address lines, except a solid, suspicious 1V. /MS is pulled high, so it should not be tri-stated either. 🤔​

Well, it's a purchase off the Bay so I guess I lost in the lottery and got a bad part... 💸​ Will try to source another and try it in the same test rig.

#electronics

Playing around with a Motorola MC6847 Video Display Generator, considering using it in my currently headless #homebrewcomputer.

I get legit horisontal sync and field sync signals out of it, and looking at the luminance output, it seems to plausibly be doing the video framing.

However, it never outputs anything on its address lines, except a solid, suspicious 1V. /MS is pulled high, so it should not be tri-stated either. 🤔​

Well, it's a purchase off the Bay so I guess I lost in the lottery and got a bad part... 💸​ Will try so source another and try it in the same test rig.

#electronics

Playing around with a Motorola MC6847 Video Display Generator, considering using it in my currently headless #homebrewcomputer.

I get legit horisontal sync and field sync signals out of it, and looking at the luminance output, it seems to plausibly be doing the video framing.

However, it never outputs anything on its address lines, except a solid, suspicious 1V. /MS is pulled high, so it should not be tri-stated either. 🤔​

Well, it's a purchase off the Ba,y so I guess I lost in the lottery and got a bad part... 💸​ Will try so source another and try it in the same test rig.

#electronics

Haven't posted much on my #Fennec6800 #HomebrewComputer but just this week prototyped a 6845 based text display for it. Doing 64x24 text on composite video. It could do 80 if I went with a slightly faster dot clock but looks good as is.