The PC8477 Demo Program is designed to allow access to all software commands and registers of National Semiconductor's PC8477 Advanced Floppy Disk Controller. The demo program will automatically detect a PC8477, DP8473 or 82077 floppy controller and allow all commands of these controllers to be implemented. This demo program will also work with any floppy disk controller that is software compatible with the NEC765. It allows the user to easily experiment with these floppy disk controllers and is controlled by a series of pop-up menus.
Also included on the PC8477 demo disk is a functional test program called "fdc_test.exe". This program will perform a series of diagnostic tests on the floppy controller. The file "fdc_test.doc", also on the demo disk, describes the operation of this test program.
GETTING STARTED
To start the PC8477 Demo Program, simply run the program called "77demo.exe" from the demo program disk. When the program is first started it will automatically perform a reset and initialization of the floppy controller. This reset is the same as the Reset With Specify menu option described later. If a reset is not desired when the program is started, type "77demo -nr" to start the program. "nr" indicates "no reset".
When it is first executed, the program will also ascertain which controller is installed in the system, whether it be a PC8477, DP8473, 82077 or NEC765 compatible controller. After this procedure is completed, you are placed in the background mode.
The background mode displays the data that was transferred from the last command. Since no data has yet been transferred, this area is blank (except for the introductory title). The top line has some other information. The top far left position is used by the port I/O routines explained later. The left center indicates the number of bytes transferred during the last command issued. The right center reflects the current state of the INT pin. The right position shows the current value of the Main Status Register in the floppy controller. This top line is only valid while in the background mode, not during the execution of a command. While in the background mode, the MSR will be polled continuously by the software. Once a popup menu is on the screen, the MSR polling will stop.
HOW TO USE THE DEMO PROGRAM
To execute a command or function, you can access the menus from the background mode by hitting the space bar. This will pop up the main menu, from which all the functions of the floppy demo program are accessed. As an item in the menu is chosen, another menu will appear if appropriate. This technique of popping up menus continues until the desired function is chosen.
There are three methods for choosing the desired selection in a menu. The space bar will advance the highlight to the next selection. The up and down cursor keys can also move the highlight. After the desired selection is highlighted, hitting the return key will execute the selection. The third method of choosing a selection is to use the "hot" key. This is done by simply hitting the first letter of a selection, (the letter in parentheses), which will both highlight and execute the selection. To abort the current menu, hit the ESC key. This will either erase the current menu or erase all the menus on the screen and return to the background mode.
After any command is finished executing, two things may occur. Commands with a Result Phase will display this status information on the screen. You can return to the background mode by hitting the space bar. If there is no Result Phase, the program will return to the background mode automatically. While in the background mode, the displayed data can be scrolled with the page up, page down, home and end keys. This data is depicted in two formats. The main block in the center of the screen shows the hex representation of the bytes transferred. To the right of this block is the ASCII character representation for each corresponding byte. The column of hexadecimal numbers on the left shows the relative address of each corresponding row of bytes.
MENU DESCRIPTIONS
Now that you know your way around the PC8477 Demo Program, you need to know what the various functions and commands will do when executed. The remainder of the user's guide will describe each function supported by the demo program. Each function in this guide is arranged according to how it is accessed in the menu structure.
MAIN MENU
(R) Reset
With Specify
Issues a software reset to floppy controller followed by four Sense Interrupt commands, a Specify command and Recalibrate command with Sense Interrupt. This function is performed automatically when program is first started.
Reset Only
Issues a software reset to floppy controller.
One Sense Int
Same as Reset With Specify except only one Sense Interrupt command is issued instead of four after the reset.
(F) Floppy Command
This section is the most useful portion of the demo program. You can execute all the commands of the floppy disk controller from this menu. For most of the floppy commands executed in the program, you will see the Command Phase bytes on the screen (see the PC8477 data sheet for the command byte listing for each command). These command bytes contain default values when the program is started, but can be easily altered. Use the cursor arrow keys to move the cursor to the appropriate bit or byte in the command block. Then enter the appropriate bit or hex value to the bit or byte location respectively.
For some commands like the read and write commands, all of the command bytes cannot fit on the screen at one time. To access the command bytes that are not shown, simply move the cursor up or down until the hidden command bytes are scrolled onto the screen. Once the command bytes have been set to their desired values, hit return and the command will execute.
When commands have finished the Execution Phase, the Result Phase bytes will be displayed on the screen, indicating whether the command was completed successfully or not. Hit the space bar to return to the background mode. If a read operation was performed, the data read from the disk is displayed on the screen.
For certain commands, the program will determine the drive selected by the user and enable the corresponding drive select and motor select outputs automatically. This function is performed for all read, write, format, verify, seek and recalibrate commands.
The Seek and Recalibrate commands will issue a Sense Interrupt automatically unless this option is disabled via the Option menu. DMA data transfers will be the default mode unless Polling mode is enabled via the Option menu.
(R) Read
Executes the Read ID or other Read Data commands. The data read during the Read Data commands is displayed in the background buffer. The Read ID command will issue 20 consecutive Read ID commands and display all the result phase bytes in tabular format on the screen.
(W) Write
Executes the write and format commands. The data written to the disk during write commands is taken from the background buffer. For format operations, the ID field header bytes written to the disk are also taken from the background buffer. You can use the Transfer File-Read menu to call up the data file "format.dat" to the background buffer for this purpose.
Other Commands
The remaining commands under the Floppy Command menu are easy to execute. Consult the floppy controller data sheet for more details about a particular command if desired.
(.) Registers
This menu allows the user to directly access all floppy controller registers. Some registers are not supported by all modes of the PC8477. For example, if the controller is in PC-AT mode, then Status Register A will be TRI-STATE. This will be evident when the register contents are returned as FF hex by the program. Also, some other PC-AT compatible controllers will not support regi
