Rich, Many VGA adapters have very large ROMs and map into memory space above 1M. The old part of the ROM that 'counts' is what is found during POST. Install one adapter at a time and map the memory space using one of those utilities that help to optimize DOS memory space. Once you know where each adapter maps its ROM, you might find two that can coexist. Jim -----Original Message----- From: vcf-midatlantic <vcf-midatlantic-bounces@lists.vcfed.org> On Behalf Of Richard Cini via vcf-midatlantic Sent: Sunday, May 12, 2019 3:48 PM To: Dean Notarnicola <dnotarnicola@gmail.com>; vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> Cc: Richard Cini <rich.cini@gmail.com> Subject: Re: [vcf-midatlantic] Monochrome and VGA together? Ok, good. I think I have to downgrade my video card from VGA to EGA because the VGA ROM is 32k not 16k. Good thing I have a few of those too :-) Rich -- Rich Cini http://www.classiccmp.org/cini http://www.classiccmp.org/altair32 On 5/12/19, 3:25 PM, "Dean Notarnicola" <dnotarnicola@gmail.com> wrote: It was possible and common for CAD and software debugging scenarios. I know MDA and CGA worked together; not positive about EGA. Should be ok as long as there's no memory address or IRQ conflicts. On Sun, May 12, 2019 at 3:22 PM Richard Cini via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote: All — I’m working on another project (with an early version of Windows) and for debugging on my AT, I need to run both a monochrome and EGA/VGA together. I’m quite rusty on this because I remember doing this long ago but it might be pre-VGA. Is this possible? Thanks! Get Outlook for iOS<https://aka.ms/o0ukef>