CP/M 80 on NEC V20

dana....@superior-ind.com

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Feb 20, 2020, 12:24:34 PM2/20/20

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I have an old Epson PC Equity where I installed a NEC V20 CPU. I have a Commodore 128 and several CPM disks with OS and applications. I have seen emulators that will utilize the V20 and mimics the operations of CPM on Dos. However are there any Boot disks out there where I can pop in a floppy and just use the real deal?

Randy McLaughlin

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Feb 20, 2020, 1:26:46 PM2/20/20

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On Thursday, February 20, 2020 at 11:24:34 AM UTC-6, dana...@superior-ind.com wrote:
> I have an old Epson PC Equity where I installed a NEC V20 CPU. I have a Commodore 128 and several CPM disks with OS and applications. I have seen emulators that will utilize the V20 and mimics the operations of CPM on Dos. However are there any Boot disks out there where I can pop in a floppy and just use the real deal?

Terrible answer, yes a boot disk to real CP/M can be done.

It would have to have the BIOS written from scratch to match your hardware. Part of the BIOS would be in 8080, part in 8088 and have code to switch back and forth (as the emulators do).

Final suggestion forget it.

Randy

dana....@superior-ind.com

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Feb 20, 2020, 1:51:09 PM2/20/20

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I had a feeling the answer would be something like that. I had hopes maybe somebody compiled something years ago that would be sitting on some obscure site today. Well, unless anybody responds otherwise I'll work with the emulators. Would anybody have a recommendation of one that utilizes the V20 to it's fullest?

Udo Munk

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Feb 20, 2020, 3:41:41 PM2/20/20

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On Thursday, February 20, 2020 at 7:26:46 PM UTC+1, Randy McLaughlin wrote:

> Terrible answer, yes a boot disk to real CP/M can be done.

Unlikely. One of the reasons for example was that the CPU switches into 8086
mode from 8080 mode on every interrupt.

> It would have to have the BIOS written from scratch to match your hardware. Part of the
> BIOS would be in 8080, part in 8088 and have code to switch back and forth (as the emulators do).

Back then it was done different:

http://www.bitsavers.org/pdf/microCornucopia/Micro_Cornucopia_%2327_Dec85.pdf

> Final suggestion forget it.

If one can find one of the software products explained in article above one can run some
CP/M-80 software on the system. Nothing doing direct I/O will work of course and there
were some other limitations too, which I forgot. I tested one of the V20 machines decades
ago, it did work to some degree, but was not exciting compared with some of the better
Z80 systems from that time.

If you cannot easily find the software for playing with this, then yes, forget about it.

Bobby Yates

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Feb 20, 2020, 9:07:57 PM2/20/20

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On Thursday, February 20, 2020 at 11:24:34 AM UTC-6, dana...@superior-ind.com wrote:

> I have an old Epson PC Equity where I installed a NEC V20 CPU. I have a Commodore 128 and several CPM disks with OS and applications. I have seen emulators that will utilize the V20 and mimics the operations of CPM on Dos. However are there any Boot disks out there where I can pop in a floppy and just use the real deal?

Might be able to modify program at bottom of this page to work. http://www.oldskool.org/guides/tvdog/emulators.html

Richard Deane

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Feb 21, 2020, 3:45:50 AM2/21/20

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On Thursday, 20 February 2020 18:51:09 UTC, dana...@superior-ind.com wrote:
> I had a feeling the answer would be something like that. I had hopes maybe somebody compiled something years ago that would be sitting on some obscure site today. Well, unless anybody responds otherwise I'll work with the emulators. Would anybody have a recommendation of one that utilizes the V20 to it's fullest?

This guy is tinkering with V20 - Previously he's known for Z80-MBC2 on Hackaday and Facebook - but now he's protyping a lashup of V20 - perhaps he has something of interest. He is Fabio Defabis, Member of Z80-MBC2 on Facebook.

Cheers
Richard

dott.Piergiorgio

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Mar 10, 2020, 5:24:29 AM3/10/20

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On 20/02/20 18:24, dana....@superior-ind.com wrote:
> I have an old Epson PC Equity where I installed a NEC V20 CPU. I have a Commodore 128 and several CPM disks with OS and applications. I have seen emulators that will utilize the V20 and mimics the operations of CPM on Dos. However are there any Boot disks out there where I can pop in a floppy and just use the real deal?

the 128 uses the Z80, the V20 (and V30) emulates the 8080. So I doubt
(aside the consistent hardware differences) that the C=128 BIOS can be
booted on your PC Equity.

OTOH, one can write a booter and BIOS for the PC Equity, taking in
account its hardware e.g. setting NEC's 8080 mode.

HTH, and

Best regards from Italy,
dot. Piergiorgio.

dott.Piergiorgio

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Mar 10, 2020, 5:39:36 AM3/10/20

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On 20/02/20 19:51, dana....@superior-ind.com wrote:
> I had a feeling the answer would be something like that. I had hopes maybe somebody compiled something years ago that would be sitting on some obscure site today. Well, unless anybody responds otherwise I'll work with the emulators. Would anybody have a recommendation of one that utilizes the V20 to it's fullest?

IIRC, there was one shareware/freeware MS-DOS emulator (early 90s) has a
switch for using NEC V20/30s 8080 mode, but I don't remember what was.
ISTR that was a really fast one, with another switch for slowing down
the LDIR-based DJNZ emulation.

Best regards from Italy,
dott. Piergiorgio.

Steven Hirsch

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Mar 10, 2020, 9:02:48 AM3/10/20

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Sydex 22NICE had a switch to use V20/V30 features.