From 9ba12217b39fd908cb0d226cb8f4dbdfa7a8d77c Mon Sep 17 00:00:00 2001 From: Scott Stone Date: Mon, 5 Sep 2016 03:03:03 -0400 Subject: [PATCH] re-add documentation to kim1 driver and added information to XML regarding usage of softlist item (nw) --- hash/kim1_cass.xml | 2 ++ src/mame/drivers/kim1.cpp | 24 ++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/hash/kim1_cass.xml b/hash/kim1_cass.xml index 069a14d5612..413b37c7c12 100644 --- a/hash/kim1_cass.xml +++ b/hash/kim1_cass.xml @@ -3,6 +3,8 @@ + + Microchess 1976 diff --git a/src/mame/drivers/kim1.cpp b/src/mame/drivers/kim1.cpp index 363c2f4f30a..b9e28e417db 100644 --- a/src/mame/drivers/kim1.cpp +++ b/src/mame/drivers/kim1.cpp @@ -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