WordPak-RS

Thanks to Gene Heskett I finally got the legendary PBJ WordPak. This cartridge is pretty rare and I never saw one for sale on eBay. Gene thankfully sold me one from his treasure hunt with a special mission: to make a clone available to anyone.



The PCB from inside:



You can see it's a 6545 based card with a 6116 static ram chip and a 2716 EPROM for the CHARGEN.

After getting the card I had to test, but it turns out no original WordPak software would work on this. This happens because this is the WordPak RS sold through Radio Shack stores and it's compatible with the Color Computer 3. The address for this cartridge is the $FF76 instead of the $FF98 found in WordPak-I and WordPak-II.

No worries, I developed a new NitrOS-9 80 column drivers and also a DECB driver to be used in Basic.



It WORKS! But I really don't like the fonts. It is too large and strange shape. I don't know what were they thinking. Maybe they made it to be more visible on common CRT TVs, who knows ? We will change it later. First, lets do a prototype board.

Cloning the Board

For this cloning process I made it the lazy way. Just created an empty project on KiCad and threw DIP sockets for every component. I didn't build the gates using fancy and, or, nand gates, instead with a multimeter and a magnifying glass I was testing each pin and using global labels. It gives more freedom to reverse engineer it. The result is:



Then layout this in the footprint editor, creating the cutout for the PCB using a ruler:



Now it's a job for the almighty FreeRouter:



Beautiful eh ? I ordered few prototypes and while they are being fabricated I decided to change the fonts.

Changing the Fonts

To change the fonts, I made a fairly complicated process that I will not cover here. Each font is 16 bytes in the ROM file although you can only display up to 9 rows. More than that the monitor stops working, too many scanlines for the NTSC composite video. Anyway I got the extracted ROM file and using image magick you can convert it to a BMP image. I opened this image in GIMP, edited and exported a new BMP. Then I made a small Python code to read the BMP, extract the pixels and generate a new ROM file. Then I burned another 2716 EPROM. I used a font that better suits me:


Assembling the Prototype

Finally, prototypes arrived:



 And here is an assembled one:



It fits the case perfectly! But upon testing I found 2 little bugs, easy to patch them though. The gerber files are already corrected:



Testing the Prototype

After fixing the bugs, a boring process debugging with the scope, the board WORKS!



New boot screen with the new pretty fonts :D

FHL O-PAK Support

I added support to FHL O-PAK in my NitrOS-9 driver so you can run DynaStar 3.0 on it:



And the work is done! 

Side by Side

I made a direct clone without any change.



B.O.M.

The list of material:
  • U1: 74LS373
  • U2: 74LS373
  • U3: 74LS10
  • U4: 74LS133
  • U5: 74LS04
  • U6: 74LS04
  • U7: 74LS20
  • U8: 74LS00
  • U9: M6116 STATIC RAM 2K
  • U10: 74LS86
  • U11: 74LS20
  • U12: 74LS74
  • U13: R6545 CRT
  • U14: 27C16 
  • U15: 74LS93
  • U16: SN7404 (Non-Schottky)
  • U17: 74LS165
  • Q1: 2N2222
  • R1: 4.7K OHM 5%
  • R2: 75 OHM 5%
  • R3: 220 OHM 5%
  • R4: 4.7K OHM 5%
  • R5: 1.8K OHM 5%
  • R6: 4.7K OHM 5%
  • R7: 4.7K OHM 5%
  • R8: 330 OHM 5%
  • R9: 330 OHM 5%
  • C1: ELKO 22uF 16V
  • C2-C15,C18: 0.01uF CERAMIC CAP 16V
  • C16: 27pF CERAMIC CAP 16V
  • C17: Leave it open.
  • C19: 0.1uF CERAMIC CAP 16V
  • P1: RCA JACK PCB-MOUNT
  • Y1: 14.31818MHZ OSCILLATOR
  • 1x DIL 40 pin Socket
  • 2x DIL 24 pin Socket
  • 2x DIL 20 pin Socket
  • 2x DIL 16 pin Socket
  • 10x DIL 14 pin Socket

Don't forget to use sockets. You can replace the 27C16 for a 27C32 if you burn the same ROM twice. You can choose the original CHARGEN.ROM or the new CUSTOM-CHARGEN.ROM (new font).

Building your own Word-PAK RS

I don't build or sell assembled boards. I don't have tools and structure for that but you can order your own boards from https://oshpark.com/ (kinda expensive, but made in America) or http://www.allpcb.com/ (cheap but made in China). You send to them the gerber files found in the files section.

Order all components from the B.O.M. and solder them. Some componentes like the R6545 you can only find in eBay or AliExpress as they are obsolete parts. Even the 2N2222 you can't find it on DigiKey but can be easily found in your local electronics store.

You will need an EPROM programmer to burn the ROM image into the 27C16. If you are planning to buy one I recommend the inexpensive TL66C MiniPro. You can find it as low as 40 dolars on eBay.

Happy soldering!

ċ
CHARGEN.ROM
(2k)
CoCo Demus,
Aug 12, 2017, 11:54 PM
ċ
CUSTOM-CHARGEN.ROM
(4k)
CoCo Demus,
Aug 12, 2017, 11:54 PM
ċ
DECB.zip
(7k)
CoCo Demus,
Aug 12, 2017, 11:54 PM
ċ
PBJ-EliteWordCaclFile.zip
(43k)
CoCo Demus,
Aug 20, 2017, 2:04 AM
ċ
WPRS-gerber.zip
(50k)
CoCo Demus,
Aug 12, 2017, 11:54 PM
ċ
nos9-modules.zip
(5k)
CoCo Demus,
Aug 12, 2017, 11:54 PM
ċ
nos96809l1v030300coco2_cowp.zip
(549k)
CoCo Demus,
Aug 14, 2017, 12:00 AM
ċ
nos96809l1v030300d64_cowprs.zip
(459k)
CoCo Demus,
Aug 14, 2017, 12:00 AM
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