I have had this idea rattling around in my head for a 65816 SBC for some time now – and I had some free time, so I put form to that thought. The design is pretty straight forward, and leverages the ECB bus and is compatible with the IO boards from the Retrobrew Computers (formerly N8VEM) project. I have a monitor running in "emulation" mode and am working on creating a native mode monitor now. I also have the code running to control the 8272 based floppy controller card.

The system has 512K RAM and 32K ROM as well as a real time clock on board.

as it stands the memory map is:

000000 - 007FFF On Board RAM
008000 - 00FDFF On Board RAM or ROM - ROM can be software selectable to 32K or a choice of a 8 or 16K bank - bank size selectable in GAL equations
00FE00 - 00FE06 16550 UART
00FE07 - FE07 RTC & ROM SIZE SELECTION FLAG
00FE08 - 00FEFF Mapped to Z80 ports for ECB bus boards (IO)
00FF00 - 00FFFF BIOS and Hardware Vectors
00FF00 - 00FF70 Native mode jump table
00FF71 - 00FFEF Emulation Mode jump table
00FFF0 - 00FFFF Hardware Vectors
010000 - 07FFFF On Board RAM
080000 - FFFFFF Open to ECB Bus

more information including schematics can be found here:
https://www.retrobrewcomputers.org/doku ... 16_ecb_sbc


I have a few extra SBCs from the manufacturing run, so if anyone is interested in building one of these -- they are listed for sale on the Retrobrew computers "board inventory" page here:

https://www.retrobrewcomputers.org/doku ... dinventory

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Dan Werner

You might find Supermon 816 useful, as it runs on the '816 in native mode.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Thanks, will check it out!

Dan

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Dan Werner

Supermon 816 is exactly what I was looking for, so I abandoned my monitor and decided to use Supermon.

I successfully got it to assemble using the WDC assembler (I want to keep all of my work in the same tools, to keep my sanity ), and everything checks out -- except reverse copies. forward works, but reverse does not.

example
T 7000 7010 5000 <- works OK
T 7000 7010 7060 <- returns to prompt OK, but fails to copy anyhting

The code is pretty simple, and as far as I can tell it assembled properly (from what I can tell the WDC toolset is picky, so proper assembly is not always to be taken for granted)

I am going to keep looking, but I was wondering if there were any known bugs in this area?

Dan

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Dan Werner

nevermind, I found the problem -- duh . . .

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Dan Werner

Amazing what a missing dollar sign can do.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Maybe you will find Jammon (Jamaica Monitor) also useful. Despite it's old, it works nicely at least for my environment. I translated it to the ACME assembler syntax for better integration into my project, which is based on C64 SuperCPU for testing and a 16-bit C64 expansion board (c't magazine, 1987) (sorry, currently just german docs available) on real hardware. In addition to the embedding glue code needed I fixed a minor bug concerning disassembling in alternate display mode and how the cpu flags are handled.
Details on request.

I will check it out, thanks!

Dan

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Dan Werner