Newbie wants to build a 6502 SBC

plasmo · Post by **plasmo** » Fri Dec 21, 2018 1:30 am

Hello,
I just registered on 6502.org. I'm a retired hardware engineer. I've designed with microprocessors but never 6502. The reason I joined the board is because I have a collection of 5-Volt dual-inline-package microprocessors over the years and I like to build them into single board computers. I have designed a generic 8-bit microprocessor prototype (G8PP) board that should be able to handle most 8-bit microprocessors of 1970's and early 1980's with some hand wirings specific to the microprocessor being prototyped. I want to try out the 6502 with that prototype approach.

I'm looking for a popular 6502 assembler that runs on PC Windows. I'm also looking for a basic monitor that can be loaded into RAM. I have used Lee Davison's 68000 version of EhBasic. I thought it would be a good goal to have 6502 version EhBasic running on the 6502 G8PP. I appreciate recommendations and helps on assembler, monitor and EhBasic. Thanks!
Bill Shen

Edit. I should mention the 6502 I want to prototype is W65C02SBP-10

BigDumbDinosaur · Post by **BigDumbDinosaur** » Fri Dec 21, 2018 3:08 am

plasmo wrote:

I just registered on 6502.org...I'm looking for a popular 6502 assembler that runs on PC Windows.

Take a look at the Kowalski Assembler/Simulator. I have made extensive use of it to develop software for my POC machines.

Quote:

I have used Lee Davison's 68000 version of EhBasic. I thought it would be a good goal to have 6502 version EhBasic running on the 6502 G8PP.

A 6502 version of EhBASIC is also available, but I don't happen to have a current link to it. Doing a search here should turn it up.

Quote:

Edit. I should mention the 6502 I want to prototype is W65C02SBP-10

It should work fine (the -10 suffix means it's qualified for speeds up to 10 MHz). Using the CMOS version gains you some bug fixes over the NMOS version, as well as new instructions and new addressing modes for existing instructions.

plasmo · Post by **plasmo** » Fri Dec 21, 2018 3:46 am

Thank you for the pointers. I will start a new topic asking about how bootstrap is done.
Bill

GARTHWILSON · Post by **GARTHWILSON** » Fri Dec 21, 2018 3:57 am

Welcome.

The Kowalski assembler & simulator mentioned by BDD above seem to be popular. I don't think there's much support in the way of a good English manual, but intensive users like BDD can undoubtedly be very helpful. I have a list of assemblers, most of them being free, on the links page of my 6502 website, at http://wilsonminesco.com/links.html#assem . One I have not used but I believe is excellent is our own forum member Andrew Jacobs' As65 assembler which has program-structure capability built in. I use Cross-32 (C32), formerly from Universal Cross Assemblers, now sold by Data Sync Engineering. It costs $99 but then you have an assembler that will work for many processors, instead of having to get another one for each. I have 65c02 program flow-control macros for it on my site at http://wilsonminesco.com/StructureMacros/ .

Lee Davison's EhBASIC for 6502 is available here and here. Unfortunately Lee passed away in 2013.

Quote:

Using the CMOS version gains you some bug fixes over the NMOS version, as well as new instructions and new addressing modes for existing instructions.

...and I have put a collection of the many improvements at http://wilsonminesco.com/NMOS-CMOSdif/ .

plasmo · Post by **plasmo** » Fri Dec 21, 2018 4:45 am

The Cross-32 is a great recommendation. I'm looking to prototype many 8-bit processors of 1970's and 1980's and I didn't like the prospect of having to learn each vendor's idiosyncrasy. I dimly recall there is another commercial universal assembler like that and cost in the $100-$150 range. Is Cross-32 only one you know of?

I learned of Lee Davison's passing a couple years ago. Regrettably, I came to the retrocomputing scene too late to have corresponded with Lee.
Bill

GARTHWILSON · Post by **GARTHWILSON** » Fri Dec 21, 2018 5:21 am

plasmo wrote:

The Cross-32 is a great recommendation. I'm looking to prototype many 8-bit processors of 1970's and 1980's and I didn't like the prospect of having to learn each vendor's idiosyncrasy. I dimly recall there is another commercial universal assembler like that and cost in the $100-$150 range. Is Cross-32 only one you know of?

I might have heard of another one, but I don't remember for sure, let alone what it might have been if there is one. C32 also gives you the tools to adapt it to a processor of your own design if you like. IOW, you don't have to write your own assembler, only the tables for this one to recognize and correctly assemble the new instructions and addressing modes. It's a very good macro assembler.

BigEd · Post by **BigEd** » Fri Dec 21, 2018 9:40 am

Welcome, Bill!

DeskMachines · Post by **DeskMachines** » Tue Dec 25, 2018 5:19 am

I use DASM for my assembler I know people don't think very highly of it but I have written a lot of 6502 code in it.
http://dasm-dillon.sourceforge.net/
runs on windows and linux.

My modular 6502 SBC uses arduino headers for the BUS for board stacking. I have my source code for the monitor program I am writing. It is incomplete and buggy but works for reading and writing bytes into ram and calling a program inserted into ram.
http://deskmachines.com/

BigEd · Post by **BigEd** » Tue Dec 25, 2018 11:50 am

(Welcome to these forums DeskMachines! And thanks for sharing your creations.)

Newbie wants to build a 6502 SBC

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