"CP/M compatible" vs. "MS-DOS Compatible" machines?

[Allison]

>
>Subject: Re: "CP/M compatible" vs. "MS-DOS Compatible" machines?
>   From: "Chuck Guzis" <cclist at sydex.com>
>   Date: Thu, 31 Jan 2008 02:06:29 -0800
>     To: cctalk at classiccmp.org
>
>> Date: Wed, 30 Jan 2008 15:44:40 +0100
>> From: Holger Veit <holger.veit at iais.fraunhofer.de>
>
>> MSDOS was much better in abstracting hardware, because it had a loadable
>> driver concept. 
>
>Loadable drivers didn't come along until MS/PC DOS 2.0.  Before that, 
>adding another device, say an extra disk drive, was a brutal 
>patchwork affair. CP/M 86 was far more advanced (for that matter, 
>CP/M Plus was too) than MS DOS 1.x.  As a matter of fact, the DOS 1.1 
>reference material included information not only on commands, but 
>system table layout, .EXE file structure and system requests.  ONE 
>disk buffer for blocking/deblocking.  Read and write transferred one 
>record to and from the DTA.  Flat file structure; file I/O done with 
>FCBs.  As a matter of fact, if you didn't know any better, you'd have 
>sworn that someone took CP/M 2.2 and ported it to the 8086.  
>
>MS-DOS 2.0 was a huge advance over 1.1; by Microsoft's own admission, 
>the goal was to get closer to Xenix in operability.  

Roger that.

>> Point is there in both cases: the hardware designers did not foresee how
>> their hardware could or should be used by software, so they basically
>> implanted the bare chips, not even respecting IRQ and DMA requirements;
>> the OS developers did not foresee usable and extensible interfaces to
>> access and abstract various hardware and just hacked something that it
>> would somehow work; and finally the application designers found the whole
>> base OS functions where plain unusable and reinvented, each one
>> differently, the wheel, leaving burnt ground for others that somehow
>> required similar functions - "thou shall not use the printer port for your
>> dongle, I have it already."
> 
>20-20 hindsight is great, but let's take it from the viewpoint of the 
>times.  There were very many CP/M systems around at the time with 
>*no* interrupt or DMA support.  Remember that the 5150 made extensive 
>use of peripheral chips that were from the 8-bit world (8237, 8253, 
>8259, 8255, not to mention the NS8250), so the fact that DMA and an 
>interrupt controller (with 8 interrupt levels yet) and a timer was 
>somewhat remarkable considering the competition.

DING!  Thats is the point.  the 5150 was running at 4.77mhz which by 
8088 standard of the day was SLOW. but it wasnt sitting the cpu in 
tight loops waiting for keypressed or FDC data ready.

Every Z80 system that did exactly that was nothing short of phenominal
to use and could easily blow the doors off a 5150. I worked with a
one off Multibus system at that time that had Z80/6mhz 64k shadow rom 
DMA floppy controller and later ST506 hard disk.  For text based work, 
cross assemblers it was light years faster.

>Although the BIOS functions came a long way as the PC evolved, MS-DOS 
>still ran on a 5150, so the added BIOS functionality couldn't be 
>exploited.

Also the early bios was only 16k than even two years later it was
twice the size.  Reason ram and rom became cheaper and larger.  
More space more functions.

>The parallel port was designed as a printer port; the fact that it 
>was used for other things can hardly be blamed on MS-DOS.  The 
>printer port does what it was designed to do extremely well.  The 
>fact that a dongle designer was so short-sighted as to not provide 
>printer pass-through functionality can hardly be laid on the 
>designers of the PC.  


>Personally, I'm surprised the light pen interface wasn't used for 
>more things.

That never caught on. I think when it could have the CPU was still
too slow to do the work.


Allison