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C64 Chronology
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Lemon 64
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RKO C64 Remixes
  Amazing site of C64 SID remixes

Who wrote this stuff?
This trivia was originally written by Jim Brain as part of the now long defunct C= Hacking Magazine, but happily Jim has kindly agreed to let me reproduce it in HTML-ized format for retro computing fans everywhere.

If you are interested in seeing the Commodore Trivia digests in their original form, take a look at this website.

For those who are interested, these pages were generated from the original text files using Perl and Velocity (and a nice template originally found here)


	On the MOS Technology's KIM-1, how many keys were on the keypad?

	23 keys.  The keypad has room for 24, but one spot is taken by
        a switch that puts the system into single-step mode.  Interestingly,
        some pictures have the switch on the upper left, some on the upper

	The KIM-1 keypad had the common 0-9A-F keys on the keypad, but
        also had some special keys.  Name them.

	GO (Go) Executes an instruction and displays the address of next,
        ST (Stop) Stops execution of program and return control to monitor, 
        RS (Reset), 
        AD (Address) Address entry mode, 
        DA (Data) Data entry mode, 
        PC (Program Counter) Displays and restores program counter to values
                             in PCL and PCH,
        +  (Increment) Increments the address without changing the entry mode.

	The KIM-1 was a set of modules that could be plugged together to
        expand the system.  Each module had a model number.  What was the 
        model number of the KIM-1 motherboard?

	The KIM-4.  

	On the 1525 line of printers, if you wanted to create the following
        graphic, what bytes would you send to the printer after turning on
        graphics mode?
        *  *
        *  *
        *  *
        *  *
        *  *

	I guess I should have stipulated that this is a bitmap.  ASCII just
        has a few limitations.  Anyway, the correct bytes to send are:
        255, 193, 193, 255.  You got these by assigning each bit in a column
        a value, and adding 128 to the result for each column.  

	What is the horizontal resolution of the 1525 line of printers?

	Character resolution:   80 chars, or 10 chars/inch (cpi).
        Graphics resolution:    480 dots, or 60 dots/inch (dpi).  

	On Commodore drives, explain the difference between the B-R command
        and the U1 command.

	The two commands read in data from a disk sector.  However, the 
        U1 command always reads a full sector (255 bytes).  The B-R
        command reads the number of bytes specified in the first byte of
        the sector.  If the first byte is a 15, B-R will read 15 bytes
        from the sector.  (From the 1581 manual)

	On the Commodore 1541 drive, what does the U: command do?

	This command has been traditionally used to reset Commodore drives,
        including the CBM 1541.  However, some early versions of the Drive
        DOS did not correctly handle this command.  In these versions, the 
        drive and computer failed to complete the command transaction 
        successfully, and what looked like a hung machine resulted.  
        Commodore later fixed this problem.  If U: seems to not work on
        your drive, try U; instead.  

	What does the first routine in the 1541 drive ROM actually do?

	The function, called SETLDA and residing at $C100, turns on the
        drive active LED for the current drive.  The routine loads the
        current drive from $7F and sets bit 3 of DSKCNT ($1C00).

	How many files will a 1581 disk drive hold?

	296 files.  Note that it is not a multiple of 144.  

	Commodore 1581 drives have a special "autoboot" feature that enables
        the drive to load and run a program off a disk upon drive bootup.
        What is the required name of the file?


	What filetype must the file mentioned in $109 be?


	To power up a 1351 mouse in "joystick mode", what must the user do?

	If one depresses the right mouse button during power-up, the 1351
        will behave just like a joystick.

	Describe the contents of the POTX or POTY registers when using a
        1351 mouse.

	Each register holds the same type of information, just for a 
        separate axis, so we will describe just one register:
        Bit:   Function
        7      Don't care
        6-1    Mouse axis position mod 64.
        0      Noise Bit. (check this bit to see whether mouse has moved)

	Commodore computers typically use most of zero page for temporary
        variables and other items.  However, both the VIC-20 and the 64
        reserve 4 bytes for user programs that need zero page memory.  Where
        are these locations?

	$FB-$FE (251-254).  I am not sure these were "reserved" for 
        programmers as much as they were just not utilized by the 
        CBM programmers.  

	Name the 16 colors available on the 64.

        Cyan (Light Blue-Green)
        Light Red
        Dark Gray (Gray 1)
        Medium Grey (Gray 2)
        Light Green 
        Light Blue
        Light Gray (Gray 3)

	Both the VIC-20 and the C64 emulate the operation of the 6551 UART.
        How many "mock 6551" registers are mapped into the memory map?

	5, from $293-$297 (659-663).  The register contents:
        $293   6551 Control Register
        $294   6551 Command Register
        $295-6 6551 User Defined Baud Rate value.
        $297   6551 Status Register 
The information in this between the lines marked by (BEGIN) and (END)
is copyright 1995 by Jim Brain.  Provided that the information
between the (BEGIN) and (END) lines is not changed except to correct
typographical errors, the so marked copyrighted information may be
reproduced in its entirety on other networks or in other mediums.  For 
more information about using this file, please contact the address 
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Jim Brain
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--------Commodore Trivia Edition #17 Questions and Answers (END)---------


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