CP/M 3.0

General discussions related to the Altair 8800 Clone

CP/M 3.0

Postby Wayne Parham » September 28th, 2022, 5:56 pm

I've been playing around with CP/M 2.2 for a while now and am ready to look at v.3.0.

Mike created a version for the Altair a few years ago, and so I'm getting ready to roll my sleeves up and dive in.


So Mike - and any others that have treaded this territory before me - what benefits does v.3.0 offer?

And a few other questions:

Why hasn't a version been created for 1.5Mb disks? Is it just a matter of "too many things to do and too little time?"

Would v.3.0 be better than v.2.2 for use with a hard disk drive? Would it be easier to create a v.3.0 BIOS that supported hard disk and floppies? Does it make sense to use the BIOS.ASM file that you (Mike) created for 330Kb drives, and modify the disk parameters to describe the physical characteristics of the 1.5Mb diskettes? And then maybe something similar to support hard disks?

I mentioned BIOS changes, but I think there's more than that, yes? Also a boot loader and cpmldr, isn't that right?

I've been reading things here and there, starting to create myself a fog to work through. Though some of you guys probably have flashlights for that fog.

Thoughts? Suggestions?
Wayne Parham
 
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Re: CP/M 3.0

Postby AltairClone » September 29th, 2022, 10:00 am

Hi Wayne,

The videos I made about CP/M 3 go through some of the new features of 3 vs 2.2. See the CP/M 3 videos here: https://altairclone.com/altair_experience.html.

CP/M 3 can do its own blocking/deblocking, so theoretically, the BIOS can be simpler than a 2.2 BIOS if you're writing your own hard disk driver. My BIOS is a track buffered BIOS so that feature doesn't matter. You might want to write a completely different driver for hard disk support. CP/M 3 also supports RAM banking so you can keep the TPA much larger even as you add code to the OS and the BIOS.

Mike
AltairClone
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Re: CP/M 3.0

Postby Wayne Parham » September 29th, 2022, 10:41 am

I saw that about the banked memory management scheme(s) in CP/M 3.0. Might be cool to make use of one of those arrangements.

On first glance, it appears that there are a few hardware management approaches employed by various manufacturers and hobbyists, and that the requisite code to implement must be written, built and linked into CP/M 3.0.
Wayne Parham
 
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Re: CP/M 3.0

Postby toml_12953 » September 29th, 2022, 1:52 pm

Wayne Parham wrote:I saw that about the banked memory management scheme(s) in CP/M 3.0. Might be cool to make use of one of those arrangements.

On first glance, it appears that there are a few hardware management approaches employed by various manufacturers and hobbyists, and that the requisite code to implement must be written, built and linked into CP/M 3.0.


It would be cool! I have CP/M 3.0 for the Tandy Model 4D but the Radio Shack implementation is terribly buggy.
Does the Due have the memory available and the chops to run it at a decent speed?
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Re: CP/M 3.0

Postby Wayne Parham » September 29th, 2022, 10:28 pm

Not sure about much of anything yet. I'm just starting out on CP/M 3.0, and not even sure if I want it yet. Just exploring.

I've made CP/M 3.0 diskettes for 330Kb drives. Gen'ed 'em for 63Kb, which gives 49Kb TPA. So far, so good.

I've also copied all the files from the diskettes onto my PC. Not as disk image files but as individual files. My plan is to create a 1.5Mb bootable disk and copy the files onto it. Not sure how much work is involved - I'm just now starting out with that. Curious how much TPA will remain. Certainly, adding a second memory bank would help there, but I'm not sure if I'll go that far. Might eventually, I dunno.

And I'm also not sure whether or not I'll work on a hard disk loader for CP/M. I might though - I have a couple of the IDE disk controllers from S100computers.com, and they're populated with flash cards. So it would be really cool to use those to create a system with two hard drives and two diskettes.
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