***NEC PC-8001 COMPUTER BITS AND PIECES*** ***NEComaniac 4-8-84 at 5:00 AM*** After obtaining what was probably one of the first of these animals in the Detroit area, I started trying to do something with it. Quickley I discovered that not only was the documentation a bit sparse, so was the hope of any help. This situation is probably true for most computer hobbyists and is what inspires the drive for user-groups and CBBS's. The following information is donated in the hope that it will answer some questions about this system and aim the PC-8001 user in a direction where he might obtain further information. Naturally it is impossible to cover all hardware and software of any system in great detail without writing a book. What I'll try and do is to explain some interesting and useful features. ***HELLO56.COM*** If you examine the listing in your Operating System handbook (The nice soft one with the pages that fall out.) you'll see that just following the statement 'CALL CALBOOT' there is a bunch of NOP's. These NOP's were set aside so you can add CALL's to additional routines of your own design. The following is an example routine which initializes the USART at your built-in RS-232 serial port. Add this routine to 'HELLO.ASM' and assemble it into your new HELLO56.COM. Remember that any useful routine that configures your hardware on Cold Boot can be accomplished this way. Insert CALL INT8251 (or whatever) where those NOP's are. Add this routine (or yours) just before the END directive. You can find out how to program the 8251 USART in nearly any book or data catalog that covers chips associated with the 8080 family. This routine sets the USART for 'devide by 64 Baudrate, 1 stop bit, even parity. INT8251 LDA 0EA66H ;This routine tells the machine that you ANI 0CFH ;want the serial port used for I/O instead ORI 20H ;of the Cassette interface. OUT 30H ;System control port STA 0EA66H NOP MVI A,40H ;Get 8251 ready for Mode word OUT 21H ;Serial Status and Command Port NOP MVI A,7BH ;Devide by 64, 1 stop bit, even parity OUT 21H NOP MVI A,15H ;TXEN,RXEN,ERROR RESET OUT 21H ;Oh, by the way the data port is 20H RET ;incase you want to go around CP/M. Remember that the routine could of been anything. How about a start- up to get the screen going a different color or different format? Don't forget to make back-ups of what you do and document it. Do you use 'FNCKEY.STR' to get your function keys set up? Why not just change HELLO56.COM to use different definitions and save disk space? ***LIGHT PEN*** Did you know that pin 5 on the Din connector for the B/W monitor is connected directly to the light pen input on the CRT Controller chip? This one is too complicated to really go into, but here's the info to get you going on this project. 1. input is positive going (Hi = true) 2. 51H is the CRTC command port. Send 60H to tell chip you want to read the light pen. 3. Read 50H twice to get the location a. first read = Character position in Row b. second read = Row number 4. the CRTC is a uPD3301 (Later I'll tell you how to get the manual) 5. Maybe you can find a simple light pen circuit in one of those old magazines you keep hesitating to throw out. ***Heath Software*** Did you know that just about any Heath software that doesn't depend on the H-19 video terminal can be run on your machine? It's true, Where else can you get C/80 so cheap or how about MACRO-80 that fancy macro assembler? Here is one way you can do it. 1. Find someone with a new Z-100 that likes to help. 2. Format one of your disks. 3. Using one of those handy disk-dump programs gratefully recieved from the CBBS (don't forget your donation-money is good) do the following. a. on the first sector, first track write the following: E5 E5 E5 E5 00 22 E5 02 08 E5 E5 00 E5 20 00 03 07 00 97 00 3F 00 C0 00 10 00 02 00 6D E5 E5 E5 b. This data allows the Z-100 to configure its second drive to the same format as your computer. c. Now it is a simple matter for the Z-100 to transfer that Heath software to your disk. 4. Remember that bootlegging is illegal and not very nice. (I got to learn not to preach.) ***Some unresolved 'Did you knows'*** Unresolved means that I definitely now it will work but I haven't figured it out totally. 1. The PC-8031 Disk unit can be programed to read and write just about every mini disk format. Ya it's true, it has its own Z-80 and its own ram and a very nice controller chip that likes being programed all kinds of different ways. This is what I got so far: a. We're dissasembling the rom and we made some discoveries. The unit can be reprogramed, can support double sided drives, and can probably use the new 80 track drives. b. The units operating system is kind of wierd, so is the hardware but if I can figure it out to a usable extent I'll pass on the information. c. The unit uses the uPD765. d. The units power supply could support four half-height double- sided drives. That would be a breakthrough in disk space! 2. By changing the console I/O driver in CP/M the computer could definitly emulate the H-19. Now we got just about all the H-89-90 software. 3. A simple circuit could allow switching the character generator to a 2K ram (6116) for a programmable character generator. Hooray Hi-Res graphics, different fonts. ***Where to get information*** Boy, has this part been frustrating!! Everyone acts like I'm a spy trying to get TOP-SECRET information. I've even tried bribing service technicians and computer stores. NEC hasn't been all that helpful either, they can answer questions about what key do you hit to enter information but little else. You can do better getting information on a MIG fighter. Here's what I did: 1. See what you can get out of NEC. a. Nec Consumer Electronics Div. Elkgrove, Ill. 312-228-5900 2. This division is good - There manuals are free and come UPS! This is for data sheets and manuals on chips. a. Nec Semiconductor Div One Natick Executive Park Natick, Mass. 01760 617-655-8833 3. I found a computer store that used to carry NEC and they were helpful and sympathetic. They ordered the service manuals for me. a. PC-8001A System Service Manual b. PC-8031A/32A Disk Service Manual c. PC-8012A Service Manual d. PC-8023A-C Printer Troubleshooting Manual Each manual cost $20.00 and aren't the best I've seen! They are vague, but still worth it because what else can you do? 4. I have a friend that doesn't get tired of my problems and knows alot about electronics. (I didn't say anyone can figure this out by himself). 5. The RoyalOak CBBS, The insight obtained here was great! ***Thanks, Keith and all you fellow computerists out there.***