XPost: comp.sys.ibm.pc.classic, comp.sys.ti, comp.sys.sinclair   
   From: uhclemLOSE.dec06@nemesis.lonestar.org   
      
   *ProteanThread*  wrote:   
   : where can i find out more information on how these commands were used   
   : (INP & OUT) in basic (for both the ibm pc and tandy/trs80 or *OTHER*   
   : machines); what ports were mapped to what devices, etc. and how were   
   : they different (z80 vs. the 8080/88)?   
      
   The port map information for a given Tandy or Radio Shack machine   
   (most of it anyway) of that era was usually (but not always)   
   found in the Technical Reference manual for that computer.   Since   
   the port (or memory map if that is what a given processor design used)   
   varied so much in those days, only product families had similar port   
   layouts.  By that I mean the Model III/4/4D/4P are fairly close to   
   one another, as are the Model II/12/16/16B/6000, the Model 100/102,   
   and the Color Computers, but comparing between these groups you will   
   find substantial differences.   
      
   There are also the one-offs, that are Tandy machines unlike any other   
   produced by Tandy, like the 2000, 5000, and the MC-10.  The Model I   
   was much more different than the Model III (its successor), when   
   you compare the Model III to the Model 4 (its successor).   
      
      
   As far as your generic programmers book goes, some hardware control   
   algorithms are generally reusable from system to system (more likely   
   processor and peripheral chipset to another), but the low level   
   details will depend on the local hardware implementation, processor   
   speed and other factors.   
      
   In the early years, Tandy computer managers grew to dislike the   
   INP/OUT functions in BASIC (mainly because of the support headaches   
   the third-party programs that used them tended to cause), so on the   
   Model II line of computers, the INP/OUT functions were omitted from   
   BASIC entirely (even the Tandy-provided debugger lost I/O commands)   
   and initially the hardware port maps were not disclosed at all,   
   with Tandy urging programmers to use the OS system calls instead of   
   going directly to the hardware.  There were a few sound reasons   
   behind this, because it was completely possible to program a Model II   
   to burn up its video system (complete with smoke and sometimes   
   flames), and a few other expensive hardware pieces were also   
   vulnerable to being destroyed due to not knowing what you were doing or   
   if you only programmed half the settings in the alloted time or   
   similar issues.  However, non-technical reasons also made this   
   hardware programming information hard to come by, even internally.   
      
      
   Frank Durda IV - send mail to this address and remove the "LOSE":   
       http://nemesis.lonestar.org   
      "The Knights who say "LETNi" demand... A SEGMENT REGISTER!!!"   
      "A what?"  "LETNi! LETNi! LETNi!" - 1983   
   Copyright 2006, ask before reprinting.   
      
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