superfabius / z80-mbc2 Goto Github PK

Hello, I am looking for an SBC that can be easily programmed from a host system and interface with that host system via a serial connection. This should not require any mechanic interaction (i.e. no plugging / unplugging / EPROM insertion, etc).

Basically, I want to use it as one can use modern development boards for microcontrollers.

Will this work with the Z80-MBC2? If yes, is where can I find the relevant documentation?

Background: The SDCC compiler has various backends. To track code size and performance regressions, benchmarks are compiled with new SDCC revisions and executed on STM8 and MCS-51 boards (resulting in the graphs at https://sourceforge.net/p/sdcc/code/HEAD/tree/trunk/sdcc-extra/historygraphs/).

However, currently no z80-related port is tested that way (despite Z80/GameBoy/Z180 retrocomputing being an important use case for SDCC). So I'm looking for a well-documented SBC that uses a Z80 or related to close that gap.

The z80-MBC2 does not implement flow control Neither in hardware - pins are o/c nor in software.

This causes a major problem attempting to send files to the MBC, dropped characters.

Using Putty normal terminal operation is on the whole ok (note Putty is very slow at sending characters and certainly does not fully feed the 115200 baud rate its character rate is more like 100 cps ie 1k baud)

Teraterm is much faster and totally overruns the Z80, If you want to get any sense out of it you need to include 250 mS (ie 4 cps) delays after each character.

This makes any attempt to paste files from PC to Z80 a non starter and seems to cause problems with Xmodem file transfer.

I have not looked further at the Mega implementation as yet but am not sure that it is going to cope.

Option to change baud rate with recompliing the Mega code would be appreciated.

Where do I find the source iLoad file : S200718.asm ?

After building up a few of these, and also double-checking on the MBC2-V20 system, I have come to the conclusion that the version of mbasic.com is corrupt on the distribution disk. It would randomly cause crashes of the Z80 (and V20) systems, particularly running startrek.bas.

Running mbasic in DDT showed it outputting to various ports (including 0xf2) on init, so I suspect this was a "customized" version. The version on http://www.retroarchive.org/cpm/lang/lang.htm seems to be authoritative, and does not crash on any of my systems.

Some days ago I was thinking about asking about putting all files in to a public Git repo but to my surprise it just had popped into existence.

\o/

Hello,

I built a Z80-MBC2 board a few years ago, and I'm now trying to make something that works with CollapseOS.
The operating system works, and I also see that the version that is in the archive is several years old. In s220718-r240620_sd_v1 see the creation date of cos.bin : June 23, 2020.
I would like to upgrade to a recent version, so I also checked the Collapse website : www.collapseos.org
There I find a whole series of newer releases, but no clear explanation how to install them. The description I see on Github, namely : https://github.com/hsoft/collapseos/blob/master/doc/hw/z80/z80mbc2.txt
no longer seems complete.

The designer (Virgil Dupras) has informed me that CollapseOS is "self-hosting". But that still doesn't clarify the mthod that cos.bin was generated. Can you give me some insight on how you handled that?

Concrete questions :

1. Which CollapseOS edition / revision is distributed for the Z80-MBC2 in the above archive file ?

2. Is there a source file with Z80 code used to create cos.bin ? Where do I find it?

3. Which compiler, and on what kind of development machine was used?

The Z80-MBC2 has unique hardware to perform character I/O to the terminal and access files on the SD card.
4) Have any adjustments been made specifically for the connection with IOS on the Z80-MBC2? If so, how?

5. The CollapseOS POSIX scripts create a file called : blk.fs
   That is as I understood the disk contents for CollapseOS. How was this converted to DS4N00.DSK ?