Doctor Dark’s Diary – Episode 17.
When issues 2 and 3 of 80-BUS News arrived together, a friend of mine
commented, “Just like busses! You wait months, and then they all come along at
once...” I bet he wasn’t the only one to think that either! I only mention
this because I think it is about to happen again. And all to save money on
postage! [Ed. – Believe what you want!]
Whatever happened to... Part 94.
Readers of another magazine called Micropower may be wondering what happened
to their “Win a CMOS RAM board competition”. So am I. I entered the
competition, and sent suggestions for five boards that I thought would be good
ideas. The results of the competition have yet to appear, although they have
been due for a long time, as indeed their magazine has been, but I thought you
might like to have a look at what I said to them. It was more or less as
follows, except that I have edited in a few extra remarks, not just to protect
myself from accusations of breach of their copyright on my material, but also
because I have thought of them since the competition, and they make the boards
even more desirable...
The 80-BUS is particularly well suited to the use of intelligent peripheral
boards, a prime example of the species being the Pluto graphics board, which
has a specification not very different from that suggested for a graphics
board in one of the early episodes of “Doctor Dark’s Diary”. One of the main
features of such a board is that it is accessed through the Z80 port
addressing system, so that it does not take up any of the system’s memory
space. I have five proposals for new 80-BUS boards, all of which would be of
this type. As far as the main processor in the system is concerned, each of
these boards would be controlled by the use of two or more ports, in much the
same way as the Pluto and Gemini IVC boards are. One port is called the
“status” port, and is used to find out whether the board is ready to receive
fresh instructions or not; the other port is the “data” port, and the
instructions and data are sent to this port. The five boards I propose are as
Intelligent speech generator.
This board would contain the following items:–
(a) Port decoding for two ports.
(b) A Z80 CPU.
(c) Random access memory.
(d) Read only memory.
(e) A Votrax SC-01 speech synthesis chip.
(f) Audio output circuitry.
The functioning of the board would be as follows. The main system processor
would send codes representing the words to be spoken to the data port of the
board. The on-board Z80 would store the instructions sent to it in the random
access memory; the control program telling it how to do this would be stored
in the ROM. During the periods when it was not reading the data port, which
would be most of the time, the Z80 would control the SC-01 chip. The software
in the ROM could be quite simple, providing only the necessary data collecting
and speech control functions, or could include software to translate from
normal text to the phonetic code required by the SC-01. If there was enough
ROM, it would be possible to provide a dictionary of commonly used words, with
their phonetic equivalents.