Programming PROMs Using the PROMPRO-8X

The following details the procedure for programming an EPROM using an IBM PC clone as a terminal connected to the PROMPRO - 8X. Note that contents to be programmed may either be entered manually or by downloading a .s19 file. However, prior to download ing a .s19 file it is suggested that you understand how to modify manually and perform the exercise in this tutorial.

In the optional exercise, and most associated projects use the INTEL 2716 PROM. Note that Intel designates their memory such that the user has some idea of what the device does. The 27 indicates an EPROM. Subsequent digits indicate the number of kbits of memory in the device. For example a 2716 is nominally 16k (2K 8-bit words) and a 27128 is 128k (16k 8-bit words). Note that the addresses of the 2716 range from 0x0000 - 0x07ff. (0x is used to indicate "hex").

This series of EPROMs are erased by exposing them to high intensity ultraviolet radiation for 20 minutes. The Computer Engineering Lab has one independent stand alone uV unit.

Erasure of a PROM results in logic ones being written in every location. Programming then is writing a zero into the appropriate locations. This has always struck me as the reverse of what make sense; much like having an erasure that blackens the paper and then writing with a white pencil, but that's life.

The PROMPRO-8X contains 128 kbits of volatile RAM. Using the terminal, you may view, edit, move, verify and do a number of other things with this data. (You are not using any of the memory or calculating power of the PC itself. The PC is simply being u sed as a 'dumb' terminal). Once the data in the 8X is what you desire, you may program (or 'burn') the PROM.

Initialization.

You should have first erased a PROM. Be certain the PROM is a 2716. Place it in the smaller Zero Insertion Force Socket, being very careful to align pin 1 on the device with the pin 1 on the socket.

Turn on power to the PROMPRO 8X. You should here the unit beep. If not, hit the reset button.

From the root directory of the PC, change directories to PROM; i.e., cd c:\prom. Execute file sdpc (Software Driver from PC). You will be greeted with a number of successive prompts;

• Select Communications Port; We are using Port 1 on the PC. Therefore enter a 1.
• Select Programmer to be Used; We are using the PROMPRO 8X; enter a 5.
• Select Baud Rate. This is the data transfer rate between the PC and the PROMPRO. Use 1200.

Specific Commands.

The following is a discussion of a number of commands which are relevant.

• ? - Note that you can use ? to return you to the menu.

• S - Select Device. Be careful with this command. This is used to instruct the PROMPRO as to what type of PROM is to be programmed. When you enter an S, a sub menu will appear which permits you to list (L) the permissible devices. Execute this and v erify that the 2716 (device 00) is the selected device. [Real damage to the PROMPRO can occur if the selected device and the device in the ZIF socket are not the same.]

• /1 - This indicates the device is an 8-bit device.

• L - Load EPROM to memory. Writes the content of the PROM into RAM.

• P - Program PROM. Writes the content of RAM to the PROM. Note that the L and P commands when combined provide a means to duplicate PROMs. See also /L and /U commands.

• V - Verify. Compares the content of RAM and the PROM and displays differences on the terminal. If the number of differences exceed the height of the screen, writing to the CRT will halt. Hit the space bar to continue. Hitting Enter will abort the listing. Once you have programmed a PROM, the V command is useful in verifying the content of RAM and the PROM are the same.

• B - Check PROM for blanks. A blank is defined as 0xff. The check for blanks will display the locations and content of locations in the PROM which are not at 0xff. This is useful in ascertaining that a PROM is erased.

• C - Checksum. Computes the sum of the data in each RAM location to 16 bits. Any carry above that is ignored. The concept of checksum is often used to diagnose problems in a microprocessor. Although it is not an absolute error checking method, it i s quite good. Note that the checksum may be any number from 0 to 65355. Note that 8 nibbles are displayed. The 16-bit checksum is the leftmost four digits.

• R - Permits the user to change the range of the addresses of interest in RAM. Default is Start Address of 0x0000, Finish address of 0x07ff if the 2716 is selected. The value of redefining the range is for fills or in selectively doing other operati ons on RAM memory. See the F and N commands.

• F - Permits the user to write the same specified data into all locations defined by the range. For example, a block of memory may be easily filled with all zeros.

• G - Move RAM memory block. I prefer to call this 'copy' memory block. Execution of the command will cause you to be prompted for the Start and Finish addresses of the block you desire to copy, and for the Destination address. The data will be copie d such that the data contained in the first and each subsequent address will also appear in the first, and subsequent addresses, beginning at the destination address.

• D - Dump memory. Causes the contents of a RAM page (256 bytes) to be displayed on the CRT. The display shows the hexadecimal value of data at each location and also the ASCII equivalent character. Execute using the character D followed by a 2-digit hex value to specify the RAM memory page. For example, to display the content of locations 0x0100 - 0x01ff; enter D01. After examining one page, you may examine the second by hitting the space bar. To escape from the command use the Enter key.

• X - Examine and optionally edit RAM memory. Causes the content of the specified 4-digit address to be displayed on the CRT. This may be changed by Ventering the new data. The content of the next location will be displayed after the two digits are en tered, or if you do not desire to change the data, by hitting the space bar. To escape from the command use the Enter key.

  Note that this command permits you to enter specific data into locations. An example of its use is X0000 which will cause the content of location 0x0000 to be displayed.

• N - Complement. Each byte in the specified range is inverted. For example, if the content were 0000 1110 (0x0e) prior to execution, it will be changed to 1111 0001 (0xf1) after execution.

• /R - Reset. If the PROMPRO locks up this seems to occasionally work.

• /L - Lock. Mistakes happen and this command seeks to lessen the chance that they will happen. When you first enter the SDPC program it is in the 'lock' mode. This means that you cannot execute the P (program the PROM) command until you have execut ed the /U (unlock command). It is suggested that you execute the /U command just prior to programming the PROM, and to avoid any accidents, to execute the /L command immediately thereafter.

• Get a 2716 PROM from the IEEE Store. Be certain that you have a 2716.

• Access the PROMPRO - 8X using the SDPC software. Use the S command and assure that the selected device is a 2716 (device 00).

• Remember to use the /1 command to indicate 8-bit format.

• Use the B command to verify the PROM is erased. If it isn't, erase it using the ultraviolet eraser.

• Use the Range command to set the range to 0x07ff. Then use the F command to write the data 0xff to all locations in RAM.

• Use the X command to program your PROM to contain the following data into locations 0x0000 - 0x000f;

  0000 FF, 0001 FE, 0002 FD, 0003 FC
  0004 FB, 0005 FA, 0006 F9, 0007 F8
  0008 F7, 0009 F6, 000A F5, 000B F4
  000C F3, 000D F2, 000E F1, 000F F0
  

• Use the F command to fill locations $0010 - $00FF with $00. Note that this requires first setting the range using the range command.

• In locations 0x0100 - 0x03FF fill with 0xaa.

• In locations 0x0400 - 0x040f;

  0400 00, 0401 10, 0402 20, 0403 30
  0404 40, 0405 50, 0406 60, 0407 70
  0408 80, 0409 90, 040A A0, 040B B0
  040C C0, 040D D0, 040E E0, 040F F0
  

• Use the Dump command to examine the content of memory.

• Use the /U command to unlock, followed by P command to program.

Stacking.

Note that we currently have may only have one PROM programmer. Please budget your time so as to avoid stacking on this machine ten minutes before the project is due.

Lock-Up.

If the machine should lock-up, the following procedure is recommended.

1. Attempt to reset using /R.

2. Try to reset using the Reset push button on the PROMPRO.

3. If all else fails, momentarily turn off the PROMPRO and reboot the PC. Note that the memory in the PROMPRO is volatile and your data will be lost when you turn off power to the PROMPRO. In practice I have found that it will not lockup unless I did something foolish.