SoftCat wrote on 2025-12-19, 16:00:

GloriousCow wrote on 2025-12-18, 23:04:

I'm afraid I never really implemented monochrome support for the EGA, because dealing with the 9-dot character timings annoyed m […]
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I'm afraid I never really implemented monochrome support for the EGA, because dealing with the 9-dot character timings annoyed me at the time as I had (what i thought to be) a nice optimized 64-bit, 8-pixel-at-time drawing pipeline. I did eventually figure that out for VGA but never back ported it to EGA.

Here's what I have for DIP switches, for what its worth. These are the physical switch states. They read inverted as closing the switch pulls the circuit to ground.

pub const EGA_DIP_SWITCH_EGA: u8 = 0b1001; // EGA 'enhanced color'
pub const EGA_DIP_SWITCH_MDA: u8 = 0b1011; // MDA emulation
pub const EGA_DIP_SWITCH_NORMAL: u8 = 0b1000; // EGA 'normal color'
pub const EGA_DIP_SWITCH_CGA: u8 = 0b0111; // EGA on CGA monitor

9-dot characters require a 72-bit processor.

There's only 8 pixels being fetched from a 32-bit VRAM location in graphics modes though. Text mode uses different buffers and only planes 0 and 1 (and plane 2 for loading a latch of 8 pixels, with the 9th pixel being a duplicate of the 8th or zeroed). Then it's simply shifted out one font pixel at a time to the display, much like with monochrome graphics modes. The only difference here is that the attribute is combined with that for font/background color to send to the attribute controller. And of course the whole deal with the CRT timings being affected as well by this setting (720 pixels of active display horizontally).

superfury wrote on 2025-12-20, 00:36:

There's only 8 pixels being fetched from a 32-bit VRAM location in graphics modes though. Text mode uses different buffers and only planes 0 and 1 (and plane 2 for loading a latch of 8 pixels, with the 9th pixel being a duplicate of the 8th or zeroed). Then it's simply shifted out one font pixel at a time to the display, much like with monochrome graphics modes. The only difference here is that the attribute is combined with that for font/background color to send to the attribute controller. And of course the whole deal with the CRT timings being affected as well by this setting (720 pixels of active display horizontally).

Yes, I'm aware of all this. I was just joking about the 72-bit processor.

I created a new topic here.
EGA Questions

Does MartyPC correctly emulate odd/even mode for EGA? If so, which emulator version is best?

SoftCat wrote on 2025-12-23, 22:23:

Does MartyPC correctly emulate odd/even mode for EGA? If so, which emulator version is best?

It should. Just use the last release.

Tried the last exe (win64) release of the MartyPC to have a look at it's EGA emulation (for comparing to what the BIOS is supposed to do in the MDA monitor case, even if the monitor colors are incorrect in that case). But I couldn't get the EGA BIOS ROM to load into it? It keeps not finding the ROM? Any idea where I should place the ROM (I tried putting it in the EGA directory next to the VGA ROM directory and even renaming it to the MartyPC's manual's ROM filename, but I couldn't get it to load?

superfury wrote on 2025-12-24, 14:42:

Tried the last exe (win64) release of the MartyPC to have a look at it's EGA emulation (for comparing to what the BIOS is supposed to do in the MDA monitor case, even if the monitor colors are incorrect in that case). But I couldn't get the EGA BIOS ROM to load into it? It keeps not finding the ROM? Any idea where I should place the ROM (I tried putting it in the EGA directory next to the VGA ROM directory and even renaming it to the MartyPC's manual's ROM filename, but I couldn't get it to load?

Yeah, sorry, this is a bug - i need to push out a fixed version soon. Get the md5 of your ega ROM, then go into romdef_ega.toml and delete the line with the rom with the md5 you don't have.

GloriousCow wrote on 2025-12-23, 22:49:

It should. Just use the last release.

Got it, thank you!

Maybe you've already answered this question before, but it's been a while, and I'm currently dabbling with pseudo-floppy disk emulation for a retro fantasy console, but does MartyPC try to emulate the FDD including seek time (stepper motor) and delays for the right sector moving under the head?

jal wrote on 2026-01-01, 22:19:

Maybe you've already answered this question before, but it's been a while, and I'm currently dabbling with pseudo-floppy disk emulation for a retro fantasy console, but does MartyPC try to emulate the FDD including seek time (stepper motor) and delays for the right sector moving under the head?

Not currently, no. A huge rewrite of the floppy system is coming, eventually.

Ok, cool, thx. Do you have any technical information about seek times etc.? I can only find information about data transfer rates, but not about the time the stepper motor takes.

jal wrote on 2026-01-02, 18:34:

Ok, cool, thx. Do you have any technical information about seek times etc.? I can only find information about data transfer rates, but not about the time the stepper motor takes.

I'd imagine it could vary a bit with drive models, and obviously stepping on 5.25" and 3.5" drives will have very different timings.
I am planning on collecting what timing info I can glean from various datasheets and having a sort of "average drive" with 5.25 and 3.5 variants.

TEAC often published useful timing info in their datasheets.
https://deramp.com/downloads/floppy_drives/te … c%20FD-55BV.pdf

stuff like this is helpful to consider in a precise model:

(b) The access motion (head seek operation) is initiated at the trailing edge of the pulse and completes within 21msec after starting the access including the settling time. For the successive access motion in the same direction, the pulses shall be input with the space of more than 6msec, while the pulses shall be input with the space of more than 21msec for the access motion in a different direction.

Cool, thx.

GloriousCow wrote on 2025-06-11, 19:04:

SoftCat wrote on 2025-06-11, 19:01:

Intel(R) Core(TM) i5-2520M 2.50 GHz
6 GB RAM

Yeah, sorry. That CPU is 14 years old. Modern phones are faster.

I know upgrading your computer is not a luxury everyone has. But there's only so much I can do. I will continue to try to optimize things, but I don't expect any miracles.

What CPU and computer would be the minimum required for MartyPC to work properly?

SoftCat wrote on 2026-01-04, 17:18:

What CPU and computer would be the minimum required for MartyPC to work properly?

Really anything made within the last 5-7 years or so should do fine. My own computer is coming up on about four years old. Despite the impression that CPUs today are only improving by adding cores, there has still been a substantial improvement in single-threaded performance over a decade+, much larger caches, etc.

I wish I could nail down a "minimum spec" but I don't have enough data or access to enough hardware for testing. I have debated buying a new "budget" laptop to try to use it as a performance baseline. I'd be interested if anyone can report the oldest system they've successfully run MartyPC on with decent performance.

MartyPC also runs extremely well on Apple silicon, so even an old M1-based mac would serve you well.

GloriousCow wrote on 2026-01-04, 17:36:

Really anything made within the last 5-7 years or so should do fine. My own computer is coming up on about four years old. Despite the impression that CPUs today are only improving by adding cores, there has still been a substantial improvement in single-threaded performance over a decade+, much larger caches, etc.

I wish I could nail down a "minimum spec" but I don't have enough data or access to enough hardware for testing. I have debated buying a new "budget" laptop to try to use it as a performance baseline. I'd be interested if anyone can report the oldest system they've successfully run MartyPC on with decent performance.

MartyPC also runs extremely well on Apple silicon, so even an old M1-based mac would serve you well.

What CPU do I need: Core i7 or will a Core i5 suffice?
What computer and CPU do you have now, if it’s not a secret?

SoftCat wrote on 2026-01-04, 17:41:

What CPU do I need: Core i7 or will a Core i5 suffice?
What computer and CPU do you have now, if it’s not a secret?

The "i5" and "i7" distinctions are just Intel marketing fluff. You might assume that an i7 is better, but a newer i5 might beat the pants off an older i7. There's an "i9" now as well as if it weren't confusing enough. That said, comparing between the same generation, an i7 will typically have larger cache which is nice, and more cores, which MartyPC won't benefit from at all.

My current CPU is a AMD 5950X, which I only have because my 5900X CPU failed very recently. Both these CPUs are AMD's "Zen3" architecture released in 2020, although they were at the top of the lineup. Zen 4 and Zen 5 have been released since.

MartyPC will also benefit from a discrete graphics card/chip, which could be the cheapest nVidia or AMD card you can buy. MartyPC isn't doing anything advanced other than running a basic shader but it just seems that integrated video is universally terrible (although that might have changed in the last few years).

GloriousCow wrote on 2026-01-04, 18:00:

The "i5" and "i7" distinctions are just Intel marketing fluff. You might assume that an i7 is better, but a newer i5 might beat the pants off an older i7. There's an "i9" now as well as if it weren't confusing enough. That said, comparing between the same generation, an i7 will typically have larger cache which is nice, and more cores, which MartyPC won't benefit from at all.

My current CPU is a AMD 5950X, which I only have because my 5900X CPU failed very recently. Both these CPUs are AMD's "Zen3" architecture released in 2020, although they were at the top of the lineup. Zen 4 and Zen 5 have been released since.

MartyPC will also benefit from a discrete graphics card/chip, which could be the cheapest nVidia or AMD card you can buy. MartyPC isn't doing anything advanced other than running a basic shader but it just seems that integrated video is universally terrible (although that might have changed in the last few years).

I see, thanks for the information.

I have a fairly high-end laptop with a Intel Core i7-9750H CPU, which is from 2o19, with both integrated Intel graphics (630) as a discrete NVIDIA Quadra T1000, and MartyPC runs fine.

What workload/benchmark would you like tested? I always found I had to do a lot of DosBox testing because low end systems would mask performance issues by dropping video frames or audio. Not sure if MartyPC would do the same.

I have a celeron N3350 4gb ram with integrated graphics running Win10. I probably even have some dual core atom thin clients in my basement.