Why isn't there a CP/M for 128K Spectrums?

[Sparky]

I know the minimum is 64K and that it needs a zilog Z80. From the toastrack onwards with 128K and the Z80, the requirements are met.

[8BitAG]

A floppy drive is part of the minimum specification.

[Sparky]

I remember there were floppy interfaces, at least for the Amstrad +2s and +3

[8BitAG]

Yes, techincally a 128K machine with a disk drive could have a version of CP/M... as the +3 did later on. CP/M+ on the +3, which I owned back in the day and used to play titles like the Infocom games, wasn't a particularly brilliant experience to use... especially if you were using 80 column software where the experience was, in I think Mike Gerrard's words, akin to watching a tennis match. (The 60 (iirc) column screen was split into two, overlapping halves, and you had to flick side to side to view each of them)

Also, from what I remember from my SAM days, the license fee for releasing a version of CP/M was ludicrously expensive (probably down to an exclusive UK distributor/reseller arrangement), which is why it was released on SAM as the "compatible system" ProDOS.

[8BitAG]

Just to reiterate... There *was* a version of CP/M for 128K Spectrums... The Spectrum +3 version from Locomotive, which came with Mallard BASIC.

https://spectrumcomputing.co.uk/entry/9 ... m_CPM_Plus

[Sparky]

Thanks, I had no idea. I have a folder full of CP/M software), it should be interesting testing it.

[PeterJ]

[mention]Sparky[/mention],

There is an interesting article from Crash magazine here:

https://www.crashonline.org.uk/53/cpm.htm

Also, some more information here:

https://www.google.com/amp/s/swarmik.tu ... 4/aaaa/amp

[lister_of_smeg]

The 128+ and +2 can't do CP/M as they always have ROM at the bottom of the Z80 address space, and CP/M requires RAM there.

With the +2A and +3 Amstrad added the 'special paging mode' specifically to allow CP/M to run.

[Lethargeek]

A floppy drive is part of the minimum specification.

any drive, it was possible to run it with a ramdisk (at least one soviet 8080-based computer did it)

[PeterJ]

https://youtu.be/8gr6PsxfUbc

[NEO SPECTRUMAN]

A floppy drive is part of the minimum specification.

any drive, it was possible to run it with a ramdisk (at least one soviet 8080-based computer did it)

there were also pure tape versions
without ramdiscs
http://sannata.org/konkurs/2011/kt1119.shtml

Yes
Russians are so angry
that they format cassettes

[Sparky]

I wonder If it would work on a +2b with SD card as storage.

[kolbeck]

I think a gotek drive is the best option, for other sd card devices I would assume that part of the cp/m bdos has to be rewritten.

[PeterJ]

This is running in Fuse with +3 emulation [mention]Sparky[/mention],

The disk images are still under copyright (so can't post here), but if you search hard enough you can find them.

[lister_of_smeg]

I wonder If it would work on a +2b with SD card as storage.

I believe it's possible with the +3e ROMS, though I've never tried it:-

https://www.va-de-retro.com/foros/viewtopic.php?t=5605

[1024MAK]

I know the minimum is 64K and that it needs a zilog Z80. From the toastrack onwards with 128K and the Z80, the requirements are met.

Actually the minimum is not 64K. CP/M itself does not need that much RAM, but the application programs often do. CP/M does however require RAM at the bottom of the microprocessor memory map, which as others have said, apart from the +2A, +2B, +3, +3B, none of the other models have this. Also the video screen area messes things up.

CP/M requires a 8080. The Z80 is mostly software compatible with the 8080. I think CP/M will also run on a 8085.
But some application programs were written only for the Z80.

CP/M is a disk operating system, so a disk drive is required (or something that is equivalent, that could include RAM disks and proper computer data tape systems). One thing that was not standard, was the disk format. It varies with the various different computer manufacturers. So there is no common standard format. To use CP/M on a system where the manufacturer did not offer support means writing and amending the relevant disk drive code.

And finally, CP/M was intended to be used with a 80 column display. It is just about useable with a 64 column display, but is not easy on the eye. Again, most applications assume you have a 80 column display.

Mark

[PeterJ]

And finally, CP/M was intended to be used with a 80 column display. It is just about useable with a 64 column display, but is not easy on the eye. Again, most applications assume you have a 80 column display.

I've not tried it Mark, but apparently there is a simulated 80 column display available:

Most CP/M packages expect an 80-column display. To get around this, Locomotive provide a simulated 80-column mode, showing 80 columns in two overlapping 51-column sections. There’s a marker on the status line to show which side you’re on. Flicking back and forth can follow the cursor, or be manually controlled. Either way it works with most packages, but makes some very hard to use.

crashonline.org.uk/53/cpm.htm

Not perfect, but at least better than nothing.

The manual is here:

http://k1.spdns.de/Vintage/Sinclair/86/ ... intro.html

[Sparky]

[
CP/M requires a 8080. The Z80 is mostly software compatible with the 8080. I think CP/M will also run on a 8085.
But some application programs were written only for the Z80.

Mark

Mark, I believe it also works on 68000

[1024MAK]

[
CP/M requires a 8080. The Z80 is mostly software compatible with the 8080. I think CP/M will also run on a 8085.
But some application programs were written only for the Z80.

Mark

Mark, I believe it also works on 68000

The 8 bit version of CP/M doesn’t, but there is a 16 bit version called CP/M-68K that is designed for 68000 series microprocessors.

Mark

[Sparky]

I just learned by watching a video that Amstrad gave free CP/M diskettes for the 6128 but not for the +3. Stingy.

[8BitAG]

I just learned by watching a video that Amstrad gave free CP/M diskettes for the 6128 but not for the +3. Stingy.

CP/M came with the disk-based 664 and 6128, as well as the 464 disk expansion.

Not really stingy... but Amstrad always looked at any way they could reduce costs. There was a cost involved with licensing the system from Digital Research. Bundling a business-orientated system with a "gaming system" wouldn't have made much financial sense; particularly when Amstrad were keen to keep the two platforms distinct.

[PeterJ]

Agree with all that 8BitAG says.

Sugar was aiming to attract the business market with the 6128. The Spectrum under Alan Sugar was focused towards gaming.



Note the 100% focus on gaming with the +3. Very much two distinct items.

[8BitAG]

It's probably worth posting a link to John Elliott's excellent CP/M resources & webpages here...
https://www.seasip.info/Cpm/index.html

[PeterJ]

The CPC6128 also has 80 column text available.

[Sparky]

The CPC6128 also has 80 column text available.

in monochrome only or in color as well?