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               ***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.***

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