Atari PC4 286/16Mhz with goodies has arrived!

[wierd_w]

4 hours ago, zzip said:

RLL has more sectors per track.  26 vs 18 I think if memory serves.    You could also format some MFM drives as RLL for extra storage.     Some RLL controllers were SCSI devices.   

Think of it this way..    drives now generally have controllers integrated in them, but back then drives were a lot dumber, and needed an external controller and thats what the MFM/RLL provided.  SCSI could talk to drives with internal or external controllers.    It all made for a big mess

Additionally, there were differences in how the bit transition patterns were written.

 

https://en.wikipedia.org/wiki/Run-length_limited#MFM:_(1,3)_RLL

vs

https://en.wikipedia.org/wiki/Modified_frequency_modulation#MFM_coding

 

RLL was more "efficient" in its encoding, which is why it could get more sectors per track, but did so at the expense of read-fault reliability being degraded compared to MFM.

 

Some drives told you straight up in their manual NOT to use them with an RLL controller, because the head could not accurately pick out the transition patterns with RLL encoding.

[leech]

10 hours ago, wierd_w said:

Additionally, there were differences in how the bit transition patterns were written.

 

https://en.wikipedia.org/wiki/Run-length_limited#MFM:_(1,3)_RLL

vs

https://en.wikipedia.org/wiki/Modified_frequency_modulation#MFM_coding

 

RLL was more "efficient" in its encoding, which is why it could get more sectors per track, but did so at the expense of read-fault reliability being degraded compared to MFM.

 

Some drives told you straight up in their manual NOT to use them with an RLL controller, because the head could not accurately pick out the transition patterns with RLL encoding.

Ha, yeah I discovered all of this after I posted and did some reading.  But kept trying to find a way to back them up.

 

Check this out!  https://www.drem.info/

 

Damn!  That price!  This is what happens when there is no competition!

Edited July 26, 2022 by leech

[Clint Thompson]

Now that it’s all done and put back together, placed near some wall space in the studio next to the STe. 
 

A nice Saturday night and what the PC4 was made for.. Larry Laffer and whatever pixelated sun bathing beach… girls

 

love that the little boom box is outputting the sound blaster audio. I didn’t have speakers and I forgot about this having the ability to accept Aux input!

[leech]

8 hours ago, Clint Thompson said:

Now that it’s all done and put back together, placed near some wall space in the studio next to the STe. 
 

A nice Saturday night and what the PC4 was made for.. Larry Laffer and whatever pixelated sun bathing beach… girls

 

love that the little boom box is outputting the sound blaster audio. I didn’t have speakers and I forgot about this having the ability to accept Aux input!

It is a seriously good looking machine.  There is some style to it.  So many of the 286 era machines I have seen pretty much all looked like Compaq or IBM.