DOS ain't dead - mainframe EBCDIC FAT

kerravon

Ligao, Free World North,
23.07.2024, 16:01

mainframe EBCDIC FAT (Announce)

So is it possible to port msdos to an IBM mainframe?

Obviously it has a different instruction set. S/370 etc. So since MS-DOS was written in 8086 assembler it needs to be rewritten. Language could potentially be anything. CP/M was written in PL/M.

I chose C.

But the FAT file system is the same. Except the mainframe uses EBCDIC normally. Can the FAT filesystem even work on EBCDIC?

With the benefit of hindsight, everything becomes obvious, allegedly.

Anyway, it's not quite hindsight, so I wouldn't say it's a done deal. It's still a work in progress.

But you can see for yourself by searching for z/pdos-generic at http://pdos.org and downloading zpg.zip

You will need a different emulator for the mainframe. I use Hercules/380 but standard Hercules works with workaround.

BFN. Paul.

mbbrutman Washington, USA, 23.07.2024, 18:12 @ kerravon	mainframe EBCDIC FAT Post reply
	The only thing that would be different or need adjustment are the filenames and volume label. The rest are just bits interpreted as numbers.

glennmcc

North Jackson, Ohio (USA),
23.07.2024, 18:29

@ kerravon

mainframe EBCDIC FAT

Post reply

> So is it possible to port msdos to an IBM mainframe?
>

Might be possible.

Step 1) find and purchase an IBM mainframe machine that's still in working condition.

:-D

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http://glennmcc.org/

kerravon Ligao, Free World North, 24.07.2024, 01:22 @ glennmcc	mainframe EBCDIC FAT Post reply
	> > So is it possible to port msdos to an IBM mainframe? > > > > Might be possible. > > Step 1) find and purchase an IBM mainframe machine that's still in working > condition. This suggests that it is difficult to find new mainframes. Are you aware that they are still sold new? They're expensive though. But that has always been the case.

glennmcc

North Jackson, Ohio (USA),
24.07.2024, 04:00

@ kerravon

mainframe EBCDIC FAT

Post reply

> > > So is it possible to port msdos to an IBM mainframe?
> > >
> >
> > Might be possible.
> >
> > Step 1) find and purchase an IBM mainframe machine that's still in
> working
> > condition.
>
> This suggests that it is difficult to find new mainframes.
>
> Are you aware that they are still sold new?

Yes, I know IBM still makes them today.

>
> They're expensive though. But that has always been the case.

Yes, _very_ expensive.

"How expensive is an IBM mainframe?
$250,000 to $4 million
Instant recovery, encryption capabilities and cloud native developments
certainly do come with a significant price tag. Each mainframe is custom built
and costs anywhere from $250,000 to $4 million. IBM hopes to see a return in
revenue in fiscal year 2020.
Sep 12, 2019

So, we 'hobbyists' could never afford a new one but would need to settle
for a used one in working condition ;-)

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http://glennmcc.org/

kerravon

Ligao, Free World North,
24.07.2024, 07:51
(edited by kerravon, 24.07.2024, 08:12)

@ glennmcc

mainframe EBCDIC FAT

Post reply

> $250,000 to $4 million

A Linux One system starts at 100k

It is unclear if you are allowed to run z/pdos on it.

And it is unclear if it is legal for IBM to stop you.

> So, we 'hobbyists' could never afford a new one but would need to settle
> for a used one in working condition ;-)

Depends how passionate you are. Most people will buy a house that is much more expensive than 100k.

If you forget about trips to Europe, forget about having kids, forget about restaurants, walk to work so don't buy a car, even hobbyists could likely get one.

Probably not very sensible though.

And that's with no peripherals. If you do ftp load, no disks except ramdisk, no tapes, and just do tn3270 over the OSA ICC, maybe it will be close to that price.

Edit: correction - 135k which includes 1 TB memory

glennmcc

North Jackson, Ohio (USA),
26.07.2024, 19:27

@ kerravon

mainframe EBCDIC FAT

Post reply

> Edit: correction - 135k which includes 1 TB memory

So, are you gonna' buy one of 'em to use for developing MSDOS to boot on an IBM mainframe ? :-D

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kerravon

Ligao, Free World North,
29.07.2024, 04:51

@ glennmcc

mainframe EBCDIC FAT

Post reply

> > Edit: correction - 135k which includes 1 TB memory
>
> So, are you gonna' buy one of 'em to use for developing MSDOS to boot on an
> IBM mainframe ? :-D

I'm working with someone with real hardware, but I develop using the Hercules emulator.

I may buy one of those myself one day, but it would be dependent on having a business retuning lots of money, not me making large sacrifices.

I believe that is going to happen, but it hasn't happened yet.

Everyone else is using x64 hardware, I'm using a mainframe.

Yep, I look forward to that.

And to all those people who say they only use Linux and won't accept windows software - I will only accept EBCDIC data files.

rmcconne

23.07.2024, 21:49

@ kerravon

mainframe EBCDIC FAT

Post reply

> So is it possible to port msdos to an IBM mainframe?
>
> Obviously it has a different instruction set. S/370 etc. So since MS-DOS
> was written in 8086 assembler it needs to be rewritten. Language could
> potentially be anything. CP/M was written in PL/M.
>
> I chose C.
>
> But the FAT file system is the same. Except the mainframe uses EBCDIC
> normally. Can the FAT filesystem even work on EBCDIC?

The EBCDIC character coding is only used at the Human-machine interface, just as ASCII, code pages, UTF or Baudot would be used. Behind that it is just bits and bytes which the machine can interpret. The real trick will be to find editors that work on EBCDIC and compilers that can read it.

It has been a long time, but I can recall seeing programs that would translate EBCDIC coded text into ASCII, and vice versa. It's quite simple to do, not at all like translating between two human languages.

Bob

kerravon

Ligao, Free World North,
24.07.2024, 01:36

@ rmcconne

mainframe EBCDIC FAT

Post reply

> The real trick will be
> to find editors that work on EBCDIC and compilers that can read it.

A fork of gcc that can read EBCDIC has been available since about 1999.

I am using a version based on gcc 3.2.3

Microemacs has been ported for several years.

All of MVS 3.8J has been available since around 2000 which gives assemblers and a linker too.

But those don't operate on a FAT filesystem.

An assembler and linker and archiver that work on the FAT filesystem have been available for about 1 or 2 weeks.

That triggered the latest OS development.