W6502SBC, a simple 6502 sbc

[willie68]

Thanks for the hints.

@BigEd
Yeah, i know, thats why i ordered a bunch of 6551, but I hoped to find at least one good one. But 100% scrap is a bit high...

@floobydust
The problem with utsource here in Germany is that the shipping costs are way too high.
€26.96 (that's almost the same in $ at the moment) It's a hobby, but ten times the value of the goods as postage...

I actually wanted a WDC W65C51, but it is currently not available here in Germany. Therefore the detour via the China goods. I've now ordered a couple of MAX3100's from a local supplier, should arrive today or tomorrow. Let's see how they do.

But that's also what makes it so exciting. You never know what you'll get...

[GARTHWILSON]

floobydust wrote:

- Rarely will you get a 65(C)51 to run much higher than the rated speed (note: I only run mine with interrupt-driven receive and transmit).

BillO has found they usually work to several times their rated speeds, even 20MHz for a 2MHz-rated one. We had some private conversation after this post of his. My workbench computer with 4MHz parts runs fine up to 7MHz, including the 4MHz ACIA1. (I didn't try the other two ACIAs at that speed, and what seemed to cause crashing just tad above 7MHz was RAM speed.)

[willie68]

Just ordered a W65C51 in PLCC package and an adapter for it.
Just in case.
The MAX3100 variant is now on the breadboard, got my first try with arduino, because of checking the schematics. Working.

[floobydust]

Just remember that the W65C51 has the xmit bit defect, which includes the DIP and PLCC versions:

viewtopic.php?f=4&t=2543&start=30#p29001

Also note that the latest WDC parts require a 1Meg resistor in parallel with the crystal to oscillate.

[willie68]

Adapter time,

PCB have come and seems to work.

[GARTHWILSON]

Nice! Can you give a link to those pins. Interplex NAS has some nice pins for this kind of application but I just looked into them for a work project and found that because they have so many combinations of options, they don't want to stock them or even start up the machines to make them until you order, and minimum order was tens of thousands of dollars, non-returnable and non-cancelable! We had to find a different way to do the job.

[willie68]

Sure, this are Pin strip RM 2.54mm, straight, 1-row, 36-pin with round contacts 0.5mm.
https://www.reichelt.de/stiftleiste-rm- ... tml?&nbc=1
Its my favorite distributor for my personal use.
Here is the datasheet:
https://www.reichelt.de/index.html?ACTI ... _DB-DE.pdf

[willie68]

Next big step done:
implementing 6551 transmit/receive and a extended version of wozmon:
https://hackaday.io/project/186414-w650 ... 5c51-die-2

Mow the next evolution is coming, a simple basic...