Engravers Network-Dahlgren System 1/100-Font Basics

System 1/100 Font Basics

Up to 3 EPROM boards may be used in the System 1 control, with switch positions on the board indicating in which order they are to be read. The number one board contains the system program EPROM's. Numbered from 0 to 6, they configure the microprocessor on the CPU board with its' functions. The chips following the system program are the font EPROM's. These contain all the information required for the engraving of letters in different styles.

There are normally three EPROM/font boards with 16 chip slots on each. Although there is an extra slot on the mother board after 3 font boards are installed, the System 1 control unit only recognizes 3 font boards. The first seven slots on the first board are reserved for the System program EPROM's. The remaining 41 chip slots are for the 2708 (1K) fonts/logo EPROM's.

Nine fonts, numbered 0 to 8 in the TRS80 software, is the maximum number of allowable `on-line fonts' in the control unit. Each font, depending on the number of lines, or complexity of the letter, varies in size. Avant Garde and Futura require 3 chips each, while Helvetica 6-line require 14. If all the fonts you normally used were 3K each, you could have 8 fonts (the maximum number) with 10 blank spaces unused.

8 fonts x 3 chips each + 7 for System = 31 chips

If all the fonts you normally used were 14K each, you could only have 2 fonts in your control unit.

2 fonts x 14 chips each + 7 for System = 35 chips

Look in your card cage (refer to Network Notebook, pages 4.14 and 4.15) and see if you have 3 font boards. If you have less than 9 fonts, and have extra blank sockets on the boards, you can add more `on-line' fonts.

FONTS PROBLEMS/CAUSES

Common causes of fonts to quit working on the System 1 control unit:

Bad font EPROM's (least likely).
Improperly inserted EPROM'S.
Bad font board (most likely).
DIP Switches on boards have been changed.
Accidentally using another font board from another control unit.
If the problem is random, and moves from font to font, the cause could be:

Bad font board.

Other control unit components.

Operator error.

Tracking Down the Problem

If you're having a problems with all of your fonts, it is most likely some other problem than with a font or font board. However, examine the fonts as shown in the procedure, to make sure your program and font chips are installed correctly, and your font DIP switch is set correctly on each font board.

If you're having problems, follow these steps in locating your problem.

Make sure you know which font you are having problems with before continuing on. Try engraving all the characters in each font. If you get the error `Character Not In Font', make a note on which font and character the problem is occurring.
Remove your font boards from your control unit. The font boards can be re-inserted in any of the available slots, except the interface slot, and in any sequence, and they will still be properly recognized.
Determine the order of the font boards. Lay all of the boards in order; in our example we are assuming that there will be three font boards.
Make sure the gold contacts where the boards are inserted into the mother board of the control unit are facing down when placed on the table. This will insure that you will read the chips on the boards in the correct order.
To determine board #1, find the board that has the program chips. For TRS80 owners the labels on the EPROM'S will have 900, 907 or 908. SuperPro owners will have 83-91907, or a similar number. Each system chip will also have a number, from 0 to 6, or a total of 7 chips. The first chip, 0, will start in position one as shown on the illustration. Thus positions 1-7 are taken up by the program chips on the first EPROM board.
Now look in position 7 of your first font board. You should notice a chip with a label similar to the illustration below.

ILLUSTRATION 1 CURRENTLY NOT AVAILABLE

The 001 is the font number; in this case 001 is the Utility font. The three digits on each font chip correspond to the last three digits of Dahlgren's part number for font. Refer to Dahlgren's font book for the number of chips for each font set. The version number of the particular font is 3.10. The 0 is the font sequence number. All control unit EPROM sets always begin with 0.
Continue following the sequence of number; 0, 1, 2, 3, 4, etc. The next font set will again start with 0 for the font sequence number. Note the font number and font sequence number of position 16 in illustration 1.
Now look at another board. See if you find the next chip in the sequence. The board with the next chip in sequence is font board #2. Sometimes a font will end on a particular board. Just look at the remaining boards) and see if you find a font starting with a sequence number of 0. Should the two remaining boards both start with 0, determine the font names and make sure the board you will later designate as #2 keeps the original order for font names you have used in the past with your jobs.
Follow the numbering sequence on board #2. When you get to position 16, again note the font number and sequence. Make sure the numbers follow in sequence.
Now continue following the numbers on board #3 to make sure the sets are complete.
Make a list of the fonts in the order that they appear in your control unit.

Now that you have identified font boards 1, 2, and 3, and the font names, make sure the DIP switches are correctly set on each board.

EPROM Board Dip Switch Positions

Board with 8 positions

EPROM board #1 - All switches off

EPROM board #2 - All switches off (except 6)

EPROM board #3 - All switches off (except 5)

Board with 7 positions

EPROM board #1 - All switches off

EPROM board #2 - All switches off (except 5)

EPROM board #3 - All switches off (except 4)

If you discover that all the fonts are in the correct order, and the DIP switch settings are accurate, we will need to try some other procedures.

Checking For Improperly Inserted EPROM'S

Even if you haven't had work done on your control unit and haven't added or changed fonts recently, you still need to check each of the EPROM's. Heat can cause chips to pop-up. I have seen two occurrences where the fonts were installed incorrectly at the factory. And it took several years before the bent legs lost contact with the EPROM socket.

Press on the top of each chip to make sure it hasn't popped up. Holding each board up to the light, examine the space between the EPROM and the socket and see if you can find a bent leg. Also look at each EPROM to see if a leg is mis-aligned outside of the socket. If you don't find an obvious problem continue on.

Changing The EPROM Sequence

Using the list you made showing the font order, find the font board with the chips that was the last font you could engrave completely in your engraving program. Locate the first chip on the board in the font sequence AFTER the good font. Your problem is either with this font board, or the next font set in sequence. If the next font set is on font board #1 or #2, go to Option 1. If the next font set is on the last board, go to Option 2. If you have a spare font board, go to Option 3.

Note: You will be removing and re-inserting chips in this next procedure. Make sure you don't bend the EPROM pins when removing and re-installing. Also make sure the notch is in the same direction as the notch of the socket it is being inserted. And make sure you insert the EPROM'S in the correct sequence.

Option 1- Problem Is Not With The Last Board

Remove the remaining chips from the board, starting with the problem font. Take the next font set in sequence, starting with chip 0, and place it directly after the last font that engraved completely. Try to use a font set that has the same number, or more, of chips as the set your are replacing. If the transplanted font takes up more sockets than the replaced font, continue on to the next board. Remove any remaining chips on the board after the newly transplanted font.

Install the font boards in the control unit and test the fonts. If the transplanted font set does not use board #2, or #3, do not install it in your control unit when testing.

If you cannot engrave ALL the letters in the transplanted font, you probably have a bad font board.

If you can engrave all the letters, the problem is with the font that was replaced.

If the problem is the board, remove all of the chips on the bad board and re-install on another font board. Change the DIP switch settings. If the board works, the problem was a bad font board. If the problem persists, you most likely have a problem with another control unit component.

Option 2 - Problem On The Last Board

If your problem area appears to be on the last board, remove the chips from the next font in board, starting with the problem font. Take the next font set, starting with chip 0, and place it directly after the last font that engraved completely.

If you cannot engrave ALL the letters in the transplanted font, you probably have a bad font board.

If you can engrave all the letters, the problem is probably with the font that was replaced.

Option 3- You Have A Spare Font Board

Transfer all of the chips on the problem board to the spare font board. Make sure your DIP switches set properly on the spare board (the same as the board you are replacing if it has the same number of switches.)

If the problem disappears, you have a bad font board. If you have the same problem, you may have a bad font or component failure in the control unit.

Miscellaneous

If your problem is intermittent, but seems to stay with fonts on a single board, you probably have a bad font board.
If you have random problems with all fonts, you are having a voltage problem. It is most likely not your font boards).
TRS80. Recently after getting the New Years cleaning urge, I was rearranging my TRS80 System 1 from one area to another. But, after I tried to start the system in it's new location, I encountered this error. After inputting the date, the engraving program attempted to make contact with the control unit. But after a few seconds it would recycle to the original screen, again asking for the date. After a scary few minutes of searching for the problem, I discovered that I had plugged interface cable (from the TRS80 to the control unit) in backwards. The red stripe on the cable should always be to the right when you are at the TRS80 keyboard looking towards the back.
I attempted to rearrange my fonts in one of my control units so that all the fonts would have the same numbers. When I tried to run the engraving program, I got an 'I' status symbol in the upper right corner of the screen. I quickly discovered that I had one of the font chips inserted incorrectly.