Altair Emulator enhancements - progress report - questions - test-drb@ccmp.vtda.org

12 Sep 2000

From: Dwight Elvey &lt;elvey(a)hal.com&gt;
...
 Hi
 One of the other problems was that even which bits were use
to handshake the transmit and receive could change depending
on how one wired the board, so just knowing the port is still
no enough. Any commercial software that didn't go through
the BIOS was asking for troubles since there was no way
to determine how the console was done. On some systems it
went through a video board and not serial, at all.
Dwight 

Therein lies the problem, as back then the average MITS or IMSAI
did not have any rom and no concept of a BIOS, it would be CP/M
that originated that concept for small systems and called it that.
Even then the CPM bios only hid the underlying IO with standard
interface and the IO could litterally be anything on the map (often was).

If anything the idea of canned IO was something unique to systems
like the SOL and a few others and rare in the s100 world.

Allison