Running MP/M II for RC2014 on the SC126, Z180 computer and compatibles.

[Talos Thoren]

I've got a new video up running Tadeusz Pycio's build of MPMII-RCBus on SCC hardware, focusing on Z180. This one just covers initial installation and loading, and future videos will cover user setup, coding, and general usage.

Thanks to tpycio for making my dream of experiencing MP/M II on real hardware a reality!

https://youtu.be/0P2QL2yFLiM

Please feel free to ask questions and share tips or tricks if you have MP/M II expertise.

Much obliged!

- David

[AngelaTheSephira]

Thank you for sharing this! I was thinking about porting it myself, I'm glad I don't have to suffer that process!

[Talos Thoren]

Here is the next video in the MP/M II series. This gives you the info you need to begin coding in C after setting up multiple users.

https://youtu.be/5v6rYzH1-_Q

Much obliged!

[Talos Thoren]

These are some lessons I've learned from the videos:

https://www.magesguild.io/lessons-from-installing-mp-m-ii-for-the-rcbus-standard/

Much of what I did in the second video becomes obsolete. The method of system administration will be covered more correctly in future content.

Much obliged,

David Hayden

[Tadeusz Pycio]

Good for you for sharing your experience. I too was very impressed when I first encountered the system. In addition to the SET command I mentioned above, it is worth taking an interest in attaching the SCHED module to the kernel. Executing commands at a set time is a useful addition. It is also worth mentioning that this is not only a multi-user system, but also a multi-tasking one.

[Talos Thoren]

Thank you, Tadeusz, I'm very glad to hear from you on this topic. I've got a question for you about how to run the system on Z80, momentarily, but first, an update:

I've played with the SCHED command and I can really see its power, in such a low performance environment. I've been taking full advantage of the multi-tasking functionality, and spent time learning to use Aztec C. I'm following along with documentation by Kevin Boone, for those interested:

- https://kevinboone.me/cpm-c.html

- https://kevinboone.me/cpm-c2.html

I've not been able to get HI-TECH-C to function on MP/M II, but I'm starting to prefer Aztec C regardless. I'll have to spend some time really familiarizing myself with the internals of the system. I'm am particularly interested in adding hardware support and creating RSPs as necessary. I've created a binary distribution of the builds I've made, and I'm working on a video to show how I've streamlined the installation for building out a fresh installation using the distribution:

- https://github.com/magesguild/MPMII-Z180_RCBUS-BINDIST

I've been working on getting the system running on Z80 using the supported memory module here:

- https://rc2014.co.uk/modules/512k-rom-512k-ram-module/

So to my question, Tadeusz, I see that the documentation requires a CTC module generating interrupts every 20ms. I'm attempting to use the SC718, here, to create this signal:

- https://smallcomputercentral.com/rcbus/sc700-series/sc718-rcbus-z80-ctc-module/

I've got everything prepared and installed but I can't boot and I'm convinced that I'm only missing the correct jumper configuration on this module.

I found a couple articles that indicate that channel one on the ctc module should be set to system clock, and that channel two should be tied to channel one as its source. I'm unclear on how to, or if it's possible to, set the jumpers to this configuration. Also unsure whether I should attempt to daisy chain the interrupt bus (which I can do on my backplanes.) I plan to take a deeper look at the schematics for this one to see if I can figure it out, even if I need to fly some wires, but maybe you know more about it already.

I appreciate any help you can provide and I am eternally grateful for the work you've done to make all this possible for me.

Much obliged,

David Hayden

[Tadeusz Pycio]

Hi David,

Interrupts every 20ms are not required to test run the MP/M.  If you do not want to modify the sources, a clock signal must be applied to channel 1 on the SC718 and the channel 1 output must be bridged to the channel 2 input (the module is fully configurable) in two ways, the simplest being JP3 1-2 and P2 4-5 (or JP3 1-2, JP4 3-4 and JP6 3-4). If other channels are selected, the system clock must be fed into the first channel and its output connected to the input of the second. A modification of the sources is then required. 

You do not need to use interrupts for SIO by setting the quecon switch to false, this will not require the configuration of the IEI-IEO interrupt cascade. When they are used, opinions are divided as to which interrupt should have higher priority - whether from SIO or CTC :) In the case of MP/M and its rather primitive console handling, I tend to favour CTC as a higher priority.

[Tadeusz Pycio]

Addendum: For Z80, set the ldrbios.z80 bootloader switches correctly (MPU180 to false) and remember the RC2014 quirk regarding SIO addressing - rc2014 switch.

[Talos Thoren]

Okay, so I've been having trouble with this. I've got the CTC set up correctly, as far as I can tell, but I think I've got something wrong with the loader portion.

I've rebuilt the ldrbios.z80 using the commands at the beginning of the code:

```

;  Build:   ZSM LDRBIOS,LDRBIOS=LDRBIOS.Z80                            
;           LINK LDRBIOS.BIN=LDRBIOS[NR,L1700]      

```

However, when I run mpm I get no output. The FTDI still accepts input, but I get no indication that the system is actually running or accepting input.

In a fit of experimentation, I grabbed an older copy of mpm.com from one of your earlier posts in this forum. Changing nothing else, but adding an older build of mpm.com to the system, I can boot into MP/M II, however, the ftdi ceases accepting input. Again, it is unclear if the system is actually running or not, but the serial line is clearly blocked.

I'm convinced that there is a problem with my build of the loader, and I'm unsure how to rebuild the mpm.com command itself as there is no build.cmd nor any build instructions for it. I suspect all I need to do is rebuild this command, but I wanted to check with you on whether that thought is correct or not, and how to do it if so.

Much obliged!

Sincerely,

David

[Tadeusz Pycio]

Hi David,

In the /Loader folder, you have loader.cmd, which, after compilation, binary links the resulting ldrbios.bin with mpmldr.bin to create mpm.com. Check the rc2014 switch in both the Loader and MPM, as it determines how the Z80-SIO is addressed.
Today, I will check the MP/M building process on my SC110 module (unfortunately, I do not have any newer models from the SC7xx family), maybe there is something I have overlooked.

[Talos Thoren]

Thanks Tadeusz!

I don't know how I missed that cmd file, I feel a bit silly. I've got it building mpm.com now, I'm still getting a hard lock up on the serial i/o after boot on both the QUEUED and non QUEUED builds of the kernel, but I'm not convinced that's a loader issue anymore. I'll do some more experimenting and report back.

Appreciate the help!

Sincerely,

David

[Talos Thoren]

I spoke too soon about the hard lock up. After fully powering down the device (as opposed to a simple reset) everything seems to be working now.

I appreciate the help, your answers have also helped me demystify some of how this works; improving my understanding of the system a little more.

Thanks for all your hard work on this project!

Sincerely,

David