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Re: [N8VEM-S100:3798] Ithaca Audio Z80 board kit UP & Running with custom monitor!

If someone is interested, I added IDE support (N8VEM IDE board) to the MINOS monitor for the Ithaca Audio Z80 CPU, and switched the console to Serial I/O (more comfortable for me), but it's easy to switch back.
I also exposed the address of some useful functions for console I/O and IDE disk reading at the end of the ROM image.

I had to cut some corners, but I did not lose any functionality, the monitor still fits 2Kb and is mostly written in C.
So now the functionalities are:
* IN/OUT from prompt
* READ/WRITE ram from prompt
* Jump to address
* XModem transfer of a binary file to RAM
* Boot from IDE: transfers the first sector of a disk to RAM (address 0x1000) and jumps to it


On Wednesday, May 28, 2014 6:37:30 PM UTC+2, Fabio Battaglia wrote:
Thanks everyone!
I imagine SDCC generated code cannot be compared to handwritten ASM done by an expert programmer, but the result seems decent enough: all the features I listed in the first post barely fit in 2k (i think I have something like 20 free bytes left...) but they are there and they work!

I'm reading Cini's guide, and just bought a copy of "The Programmer's CP/M Handbook" (in the meantime I'll use the copy linked by Birkel). Sadly as I'm away I have to postpone most of the work until the weekend and even then I have an higher priority task of trying to dump some bipolar-roms in two compupro boards I got (first thing I do when I recover a piece of hardware is dump everything I can from it).

On Wednesday, May 28, 2014 5:48:43 AM UTC+2, Crustyomo wrote:

Nice going! It's S-100, so imho, it's very much on topic.  Aren't you afraid writing in C would take up the whole 2K? (and that's just to initialize the variables).  I guess SDCC must be very a very slim C. 

Re: Bootstrapping CP/M,  Rich Cini wrote a great guide on bootstrapping it.  Between reading a few chapters of "The Programmers CP/M Handbook" by Andy Johnson-Laird and Rich's guide, I was able to boot up CP/M.
This book is available somewhere as a download, but you can get a real copy pretty cheap on Amazon.


Date: Tue, 27 May 2014 13:04:44 -0700
From: hkz...@gmail.com
To: n8ve...@googlegroups.com
Subject: [N8VEM-S100:3798] Ithaca Audio Z80 board kit UP & Running with custom monitor!

Ok, ok, this is offtopic as the Ithaca Audio is not a N8VEM board, but I got it as a bare board, built and debugged it... so it still somewhat related :-)
I was able to get this board from 1977 up and running in my N8VEM-based system and took the occasion to write my first monitor from scratch, as an exercise.

This board fits a 2708 EPROM by default, or a 2716 after a simple mod (specified in the manual itself), so that is 2kb worth of space for my monitor: i decided for a mix of C (using SDCC) and ASM  and this is the result.  https://github.com/hkzlab/minos-z80-monitor

The monitor is quite simple: all its "features" can be summarized as
* I/O using the N8VEM console I/O, but easy to redirect on a serial console
* Supports READ/WRITE of a single byte from memory
* Supports IN/OUT from a port
* Supports jumping the  execution to an address
* Supports XModem transfer to RAM at 19200bps using the N8VEM serial board/
Enough for a small development system (not that I really needed all this with the fantastic N8VEM Z80 cpu board I have...) and also as an example of a small SDCC project.

Now I really need to read up on bootstrapping CP/M...
I haven't had this fun with an hobby in ages :-)

Bye everyone!

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