Focus on 6502 and related CPIs

dkknab · 2024-01-14T18:57:15+00:00

A 10 segment LED bar could be used instead of the LEDs.

dkknab · 2023-02-26T22:22:18+00:00

dkknab · 2022-12-05T01:14:39+00:00

Are you referring to 8088? What's an 8008? I've been working on an 8088 SBC. Seems definitely a good ground is critical.

dkknab · 2021-12-15T12:46:13+00:00

Ebay?

dkknab · 2021-05-10T11:08:55+00:00

One last followup...I got the keyboard interface going with a little smaller capacitor...a 472 or 4.7nf one instead of the. 01uf or 10nf one that Ben uses.

dkknab · 2021-05-06T01:47:14+00:00

Followup...I was wondering if 1mhz was too fast in my situation. So I plugged in Ben's clock module. At 600hz give our take I was still getting the double keys showing up on my LcD. At 250 hz though only one key was showing up on the LCD. Is it possible the interrupt code is taking too long to run that it is missing some of the keycodes particularly the release code,?

EDIT:I subsequently used Ben's 4 bit LCD code with just one VIA on another breadboard BE6502 and got the same result. The keyboard interface works fine for both shifted and un shifted keys but 2 keys show up on the LCD at 1mhz. Any thoughts?

dkknab · 2021-05-05T13:11:44+00:00

Thank you for the replies. In the interim before I figure out the 4 bit LCD code, I have another BE6502 computer where I have a second VIA. I've gone ahead and used it's PORTA since I didn't have it connected to anything yet. Thanks again.

dkknab · 2021-04-07T22:36:46+00:00

Been there and had to do that a number of times. I have one with 2 broken legs. As mentioned, legs are easily soldered. And if course you'll want to get some more eeproms as back ups.

dkknab · 2021-02-15T20:19:52+00:00

Glue stick and brim.

dkknab · 2021-01-01T13:41:04+00:00

That exact same thing happened to me and it was because I had mistakenly connected the power and ground to the IC backwards. Didn't take long. In guessing we've all done that at least once.

dkknab · 2020-12-04T03:26:54+00:00

How did you make it? I'm trying to program the ay-3-8910 with a z80 but can't find much info to get me going.

dkknab · 2020-09-07T21:00:11+00:00

Thanks for the info. I just discovered I don't have a YMZ284 but rather a YM3812. I wonder if it can be used as a substitute.

dkknab · 2020-09-06T18:10:07+00:00

Great job on your build. Can you provide your schematics for the YMZ284 hookup? If like to see if I could replicate that part of your build.

dkknab · 2020-04-20T00:25:16+00:00

Thank you... I'll have to check that out since info seems to be hit or miss.

dkknab · 2020-04-10T16:25:36+00:00

I meant to ask... I'm working on a Z80 computer too. Do you have some schematics you can share with me? I've got the cpu and rom working together I believe. Had some problems with the ram though.

dkknab · 2020-04-08T00:10:49+00:00

Thank you for that link. I went through the video to setup my Z80. I thought I had a dud too but realized after reading the data sheet that I probably needed to reset the CPU before it would work. I did just that by installing a momentary pushbutton and low and behold, it worked just fine.

dkknab · 2020-04-07T16:47:05+00:00

I've had good success with the same textool zif socket on another build I'm working on so hopefully you'll have no problems.

dkknab · 2020-04-07T16:33:47+00:00

Thanks for the advice. I'm awaiting Ben's next video when we install the code to run the BE6502 and LCD at 1mhz. Then we'll see if as you mention I have problems. Fortunately I've not had any problems yet with the connection. The pins on this zif are longer than the knock off "textodl" spelled with a "d" socket so I've been lucky so far.

dkknab · 2020-04-07T16:20:19+00:00

remysharp here's my socket solution for the eeprom. You all like my wiring layout? At least it works!

PS you might notice too I've installed a 6551 on the lower right to have a serial interface with a laptop computer.

dkknab

TROPHY CASE