I know this is an old thread and I hate to bring back a zombie thread, but this is one of the few results that come up in Google searches for this model and I have some information that may be useful to future Googlers and maybe some of the thread participants if they still have this model. Besides, this thread has been brought back from the dead a couple times already :D
First, a link to the
very-hard-to-find service manual. This is actually for a PC-4602, but they appear to be identical machines. I have not found a single discrepancy other than the model name.
By and large, the MZ-100 is a rebadged PC-4600 as far as I can tell. The BIOS chip on mine even has "PC 4600" printed on a sticker. The board layout and options seem to be similar, if not identical. The laptop came in two configurations, one with dual 720k 3.5" floppy drives, and the other with a single 720k 3.5" floppy and a 40MB hard drive. I had one of these as my first ever laptop. I bought it used when I was in high school for something like $25. I actually lugged this thing to school back in 2000-2003 lol. I was definitely one of the "cool kids"... Now, 20 years later, I paid $299 to ship one over from Egypt with a badly marred screen. Oh nostalgia...
Anywho. Some info about the machine:
- The CPU is a NEC v40 running at 10MHz. The v40 emulates an 8086 CPU but also has the expanded instruction set of the 8088 (not pin compatible).
- The board has provisions for an optional 8087 Math Coprocessor. I don't know if any other components need to be added or if any jumpers need to be set. See the service manual if you want to add one.
- The display is a Supertwist LCD panel with Electroluminescent (EL) backlight. It supports 80 characters x 25 lines (640x400 pixels)
- It supports CGA, MDA, and AT&T graphic emulation (this is from the PC-4600 brochure. I don't know how to test this. My BIOS shows "Graphics" or "Monochrome". It's very possible that some display modes are only supported with the optional external graphics card and an external monitor. That was very common for portable computers of this time period. I can tell you that the laptop is capable of playing MS Flight Sim 4, albeit somewhat slowly lol.
- 128KB of VRAM
- It has 640k of RAM standard and supports an additional 1MB (1.6MB total) through an optional expansion board
- Expansion boards included:
- For CN13 (one at a time):
- CE-451M Modem card with serial(RS-232C) interface (US/Canada only)
- CE-451B serial card (RS-232C)
- For CN11 (one at a time):
- CE-451A Color/Monochrome CRT adaptor
- CE-452B ROM disk card
- CE-453B 1MB EMS memory card (EMS 3.2)
- Dual 720k 3.5" Floppy or one 720k and a 40MB HDD
- Has the option of an external video card, but these are all but impossible to find and I haven't seen anyone replicate one.
- Power is DC9V 2.5A with center NEGATIVE. Be careful, this is not a common polarity.
- The battery was a "NP4.2-6H" 6V, 4.2Ah Lead-Acid battery and was manufactured by Yuasa Battery Co., LTD of Japan. I can supply measurements/pictures if anyone needs them. You can find Lead Acid batteries in this voltage, but good luck finding one small enough to fit in the enclosure.
- Per the service manual (linked below) the DIP switches on the bottom have the following functions (everything following the dash on each line are my notes):
- 1: System all reset ON/OFF - setting this to "ON" and turning on the power results in the CMOS being cleared. Nothing displays on the screen until you return this switch to "OFF" and power the unit on again
- 2: Not used - This was found to be false. It actually enables the external floppy option in the BIOS. With this OFF, you cannot change the drive selection to 3.5". With it ON, you can.
- 3: Speaker volume LOW/HIGH - OFF is high, ON is low.
- 4: Speaker control (without alarm) ON/OFF - Turns the internal speaker on and off. NOTE: The power alarm (beeps if you close the lid while the computer is on) and the low battery alarm do not work if this setting is "OFF", even if enabled in the BIOS. However, the "Low Battery" LED on the keyboard will still illuminate. Just no sound.
- 5: Alarm control (Low Battery/Shut off Alarm) ON/OFF - turns on/off the low battery alarm. Also, if this is off, the power alarm will not work either. The power alarm just trips the battery alarm. You can see this by pressing the small momentary switch at the top of the keyboard that tells the computer when the screen is closed. The "Low Battery" LED will illuminate when this button is pressed if the the "Power Alarm" feature has been enabled in the BIOS.
- The BIOS settings can be accessed at any time by pressing the "Set Up" key. You do not have to be at the boot screen. You can enter the BIOS even when DOS applications are running. The BIOS will display and return you to the DOS application when you exit the BIOS by pressing the "Set Up" key again. Execution of the DOS application is paused while you are in the BIOS setup screen.
- To answer the questions about the various pin connectors on the board, the service manual has them labeled as the following (the manual also includes full pinouts of the connectors!):
- CN1: LCD
- CN2: SW - power switch
- CN3: SPKR - internal speaker
- CN4: LED - the 4 indicator LEDs above the keyboard (Power, Low Battery, Drive A, Drive B)
- CN5: PS - power supply (grey ribbon cable that runs from the power board to the motherboard)
- CN6: KEY - Keyboard (white ribbon)
- CN7: ??? - there doesn't seem to be one. The manual skips it and I don't see one on my board. Perhaps a feature they decided to remove late in the process?
- CN8: FDD - floppy drive controller
- CN9: XFD (I think? It's a pretty bad copy) - external floppy drive connector
- CN10: PRINTER
- CN11: CRT - this is the header for the optional, and impossible to find, external video add-in card
- CN12: SIO - serial in/out - the 9 pin RS-232 serial port
- CN13: MODEM - I assume there was an optional modem card also. I haven't seen anything on this yet. Probably because I haven't cared
- CN14: HDD - Mine is an unpopulated header. I have no idea if there are other components required or if there is some sort of interface card/board that is needed. I do wonder if this would take either an MFM drive or (less likely) IDE without need for a controller. I did notice that there is a jumper (J1) near the keyboard connector that has FD (populated on my computer) and HD (unpopulated). So I believe this would need to be jumped in order for the computer to become aware of the the hard drive.
- CN15: HDPS - power supply for the optional on board hard drive
- CN16: EXPBUS - expansion bus. This is an unpopulated header on my board. There's a project linked below that got this functional and added 2 ISA slots to a PC-4600. So I think it's possible with these, as well.
- CN17: EMS MEMORY - This is an unpopulated header under the keyboard. I believe it's for the optional memory expansion board.
I'm also attaching some reference photos of the motherboard and power board for those that may need them in the future.
A note on the power board: There is a tantalum capacitor on the bottom left of the board near the gray ribbon that runs to the motherboard. It's marked "C39" on my board. Test this to make sure it's not shorted. Mine was when I got the machine. These older tantalum capacitors are known to fail catastrophically. Mine had definitely gotten hot as it and the components around it were blackened and smelled of burnt electronics. I suggest that even if yours is currently working, to swap it for a new one. I bought 20 of them for $14 on Amazon, you can probably get them cheaper if you have an electronics supplier near you. It's values are 47uf 16v. Tantalum capacitors often short when they fail and can take other components or board traces with them sometimes, so it's worth the investment.
Also of some interest, someone has designed an
external ISA expansion card for the PC-4600 that will very likely work on these as well. The same person also reverse-engineered the external floppy connector to get a
5.25" floppy drive working with the same machine. Let's hope that they decide to play with the external video at some point. There's hope, as these two projects were both done in March of '23! I love that computers from the 80's are getting new components in 2023!