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re-add documentation to kim1 driver and added information to XML regarding usage of softlist item (nw)

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Scott Stone 2016-09-05 03:03:03 -04:00
parent 9ccda04d17
commit 9ba12217b3
2 changed files with 26 additions and 0 deletions
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hash/kim1_cass.xml
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@ -3,6 +3,8 @@
<softwarelist name="kim1_cass" description="KIM-1 cassettes">
<!-- Instruction Manual for use and loading of Microchess is available at viewing and download at -->
<!-- http://archive.computerhistory.org/projects/chess/related_materials/text/4-1.MicroChess_%20Manual_for_6502.Micro-Ware/MicroChessManual.PETER_JENNINGS.062303071.sm.pdf -->
<software name="mchess">
<description>Microchess</description>
<year>1976</year>

24
src/mame/drivers/kim1.cpp
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@ -27,6 +27,30 @@
1873 press GO to load tape
NOTE: save end address is next address from program end
The cassette interface
======================
The KIM-1 stores data on cassette using 2 frequencies: ~3700Hz (high) and ~2400Hz
(low). A high tone is output for 9 cycles and a low tone for 6 cycles. A logic bit
is encoded using 3 sequences of high and low tones. It always starts with a high
tone and ends with a low tone. The middle tone is high for a logic 0 and low for
0 logic 1.
These high and low tone signals are fed to a circuit containing a LM565 PLL and
a 311 comparator. For a high tone a 1 is passed to DB7 of 6530-U2 for a low tone
a 0 is passed. The KIM-1 software measures the time it takes for the signal to
change from 1 to 0.
Keyboard and Display logic
==========================
PA0-PA6 of 6530-U2 are connected to the columns of the keyboard matrix. These
columns are also connected to segments A-G of the LEDs. PB1-PB3 of 6530-U2 are
connected to a 74145 BCD which connects outputs 0-2 to the rows of the keyboard
matrix. Outputs 4-9 of the 74145 are connected to LEDs U18-U23
When a key is pressed the corresponding input to PA0-PA6 is set low and the KIM-1
software reads this signal. The KIM-1 software sends an output signal to PA0-PA6
and the corresponding segments of an LED are illuminated.
TODO:
- LEDs should be dark at startup (RS key to activate)
- hook up Single Step dip switch