[AtariAge + Atari Q&A]

Will Atari restart falcon 030  That would drop the second-hand prices

[NTSC core for VBXE?]

On 9/3/2023 at 1:39 PM, Piotr D. Kaczorowski said:

I need to send flowers to the lady from your company's secretariat. She may have violated "RODO" a bit, and I was shocked myself. The important thing is that the issue concerned a larger matter.

Dude, if you called his workplace to find and contact him, you are seriously spooky and I'd keep away from you.

[Percom and mydos]

Hey,

 

Until now, my understanding of the PERCOM block (and send percom command) was that this block configures the drive with selected parameters.

If any of the parameters is wrong, percom block is discarded. If parameters match one of the drive's densities, they are set hard, until next

put percom. So after setting the drive to FM with put_percom command, the drive sits there in FM until commanded otherwise by another PUT PERCOM.

Is that understanding OK?

 

Now, mydos.

If configuration is read by percom, and not by get status, Mydos does not see the difference between

SD and ED other way than by sectors per track number. FM/MFM flag is discarded.

 

So if you have ED disk, and boot mydos off it, the percom block that is sent to the drive is

for the FM/ED (which is wrong). So the dos cannot read DUP.SYS because the drive is already in FM and the disk is ED.

 

Perhaps FM/MFM flag ( Percom[5].bit2 ) in PERCOM should be discarded? I don't know, it's there for a reason.

How does the original PERCOM drive handle this?

 

Regards

 

OK, nevermind, seems that I was mistaken. Putting percom block to the drive seems not to mean reconfiguring it at once.

It's needed for other commands that will come later. Drive should not switch densities JUST after writing percom to it.

It's a parameter block for other commands, not a command itself. No?

[Percom and mydos]

Hey,

 

Until now, my understanding of the PERCOM block (and send percom command) was that this block configures the drive with selected parameters.

If any of the parameters is wrong, percom block is discarded. If parameters match one of the drive's densities, they are set hard, until next

put percom. So after setting the drive to FM with put_percom command, the drive sits there in FM until commanded otherwise by another PUT PERCOM.

Is that understanding OK?

 

Now, mydos.

If configuration is read by percom, and not by get status, Mydos does not see the difference between

SD and ED other way than by sectors per track number. FM/MFM flag is discarded.

 

So if you have ED disk, and boot mydos off it, the percom block that is sent to the drive is

for the FM/ED (which is wrong). So the dos cannot read DUP.SYS because the drive is already in FM and the disk is ED.

 

Perhaps FM/MFM flag ( Percom[5].bit2 ) in PERCOM should be discarded? I don't know, it's there for a reason.

How does the original PERCOM drive handle this?

 

Regards