Loading CONFIG.SYS in Altirra

[phaeron]

On 5/9/2020 at 10:09 AM, flashjazzcat said:

Perhaps @phaeron can shed some light.

 

With Fastboot enabled, I see in the debugger (after monitoring SDX read requests on sector 1 of the boot volume) that high level emulation is stepping in and bypassing the PBI BIOS:

Pictured is a read operation with DUNIT = 3 (CONFIG.SYS volume). Enabling SIO Override Detection does not make a difference, so my advice is to ensure Fastboot is disabled.

 

 

Fast boot intercepts requests to non-existent disk drives, so if there is no disk mounted on D1: it will suppress those commands. SIO Override Detection can't work here because that works by letting the first request through, which would defeat the purpose. Switching to PBI intercept should work, though I think there may be issues with SDX using a different priority order than the Atari OS for PBI devices.

 

[KPeter]

I have been trying (without success) to load CONFIG.SYS from D1: APT drive in Altirra, even though I have set the parameters correctly in the BIOS,

It works without issue on real hardware, U1MB+SIDE3, so looks like some sort of issue/setting is there in Altirra. No matter I define D1: as a Boot drive or not a Boot drive.

What is the solution? I am using Altirra 4.10 .

Thank you,

Peter

[TGB1718]

In U1M set boot drive to D1: and CONFIG.SYS to D1:

works for me

 

[+Stephen]

8 hours ago, KPeter said:

I have been trying (without success) to load CONFIG.SYS from D1: APT drive in Altirra, even though I have set the parameters correctly in the BIOS,

It works without issue on real hardware, U1MB+SIDE3, so looks like some sort of issue/setting is there in Altirra. No matter I define D1: as a Boot drive or not a Boot drive.

What is the solution? I am using Altirra 4.10 .

Thank you,

Peter

Make sure that Altirra is not using the "fast boot" option.  Go to Configure System/Computer/Acceleration.  If that option is checked, it will cause that issue.

[KPeter]

On 11/30/2023 at 2:58 AM, TGB1718 said:

In U1M set boot drive to D1: and CONFIG.SYS to D1:

works for me

 

Tried, does not work.

Thank you

Peter

[KPeter]

On 11/30/2023 at 6:42 AM, Stephen said:

Make sure that Altirra is not using the "fast boot" option.  Go to Configure System/Computer/Acceleration.  If that option is checked, it will cause that issue.

Yes, this works what I expected. Thank you,

Peter

[TGB1718]

On 11/30/2023 at 2:42 PM, Stephen said:

Make sure that Altirra is not using the "fast boot" option. 

That old cookie, completely forgot about it, it's tripped me up a few times in the past

 

Often wondered, is it a bug/feature of Altirra ?

Edited December 3, 2023 by TGB1718

[+Stephen]

7 hours ago, TGB1718 said:

That old cookie, completely forgot about it, it's tripped me up a few times in the past

 

Often wondered, is it a bug/feature of Altirra ?

Not a bug - if I understand correctly, some of what it bypasses in the original OS code to make the machine boot faster is needed to make the U1MB properly read the config.  @flashjazzcat I'm sure can fill in the details.

[flashjazzcat]

Avery's post at the top of this page explains it better than I could.