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Frequently Asked Questions (FAQ)

Last revision of this page: January 25, 2025

If you really want to know more about Kaypro computers, you must read The Kaypro - Micro Cornucopia and Mr. Kaypro - The Computer Journal. All your questions will be answered there.

Processor CPU

Floppy Disk Drives (FDD)

Power Supply Unit (PSU)

Video (VID)

Modifications (MOD)

Monitor ROM (ROM)

Character ROM Generator (CHR)

I/O Interfaces (IO)

File Management (FLM)

Other Troubles (TRB)

General (GEN)

Processor (CPU)

001 - What is the correct CPU (speed) for my Kaypro?

  •  Z80 CPU, 2,5 MHz - Kaypro II/2/4
  • Z80A CPU, 4 MHz - all other Kaypro's
  • Z80B CPU, 6 MHz - for the 5 MHz mod
  • Z80H CPU, 8 MHz - for the 7 Mhz mod

Floppy Disk Drives (FDD)

001 - Can I use 8" floppy disk drives on a Kaypro II or 4 ('83)?

Yes, you can but you will need a special monitor ROM and an additional adapter. See Micro Cornucopia, Number 25, August-September 1985.

002 - Can I use four floppy disk drives on a Kaypro II or 4 ('83)?

Yes, you can but you will need a special monitor ROM and an additional adapter. See also Micro Cornucopia, Number 17, April 1984, page 19 and Micro Cornucopia, Number 21, December-January 1985, page 40

003 - Can I use four floppy disk drives on a Kaypro 10?

No, you can not, see at the end of the paragraph.

004 - Can a 96 tpi drive read and write floppy disks formatted with 48 tpi?

Yes, it can, but ... read this article. See also Micro Cornucopia, Number 15, December 1983, page 15.

005 - Can I use a 96 tpi disk drive with 784K per floppy on a Kaypro II or Kaypro 4?

Yes, you can. Read this article. See also Micro Cornucopia, Number 15, December 1983, page 14.

006 - Can I use a Gotek/FlashFloppy disk drive on the Kaypro?

Yes, you can. There are lots of information on the internet. Start reading here.

007 - Can I swap drive B to drive A just for testing purposes on a Kaypro II or Kaypro 4?

Booting from drive B on an Kaypro II or 4 [03]

008 - How can I repair bad floppy disks?

Kugram - Repairing bad floppy disks

009 - Kaypro II - I have often BAD SECTORS on drive B! What can I do?

According to Micro Cornucopia #issue 48, July/August 1989, page 76 try changing the TTL LS241 at U49 and U62.

Power Supply Unit (PSU)

001 - Which voltages have the Kaypro power supplies?

The voltages are +5V, +12V and -12V

002 - Are the Kaypro power supplies switchable from 110V to 220V?

Yes, they are.

003 - How many watts of output have the Kaypro power supplies?

Standard is 75W or 85W. Only the older Kaypro II and 4 ('83) have 65W.

004 - Can I replace an old Kaypro power supply with a modern one?

Yes, you can. You need a triple output PSU (see 001) like the MEAN WELL RPT-75B or RT-85B.

Video (VID)

001 - Can I reverse the video - black characters on green background - on the Kaypro II?

Yes, you can. See Micro Cornucopia, Number 13, August 1983, page 23

002 - How can I quickly check the video circuitry on an 81-110, 81-240 or 81-180 motherboard?

According to the "Kaypro Technical Manual", put in a blank EPROM. If the video display does not show a screen filled with alternating aposthrophes and "9"s, you have a problem in the video RAM or associated video circuitry.
... an erased eprom is filled with OxFFs. Which is the RST 38 opcode. The restart (RST) opcode jumps to address Ox0038 and starts running code from there. So it hits Ox0039 which is another OxFF which jumps to Ox0038 again but now pushes Ox0039 onto the stack. The stack 'grows' down from xFFFF, so quickly all of RAM fills up with 0x0039 (Ox00 is ' in the Kaypro character ROM and 0x039 is '9') ... [04]

Modifications (MOD)

001 - Can a Kaypro II or 4 ('83) be converted to 4 or 5 MHz?

Yes, they can easily be converted to 4 or 5 MHz with just a few jumpers, see Micro Cornucopia, Number 13, August 1983. You will also need a Z80B (6 MHz) and an EPROM with 350 ns or faster.

002 - Can a Kaypro II or 4 ('83) be converted to 7 MHz?

Yes, they can be converted to 7 MHz. See Micro Cornucopia, number 33, December-January 1987, page 56. You will also need a Z80H (8 MHz) and an EPROM with 200 ns. This mod is NOT for '84 Kaypros!

003 - Can a Kaypro II be converted to a Kaypro 4 ('83)?

Yes, it can be converted to a Kaypro 4 ('83). See Micro Cornucopia, Number 15, December 1983, page 14.

004 - How to count the pins on an IC?

By convention, the pins on an IC are numbered counterclockwise, starting with the upper-left pin closest to the clocking mark. So, for example, with the clocking notch orienting the chip at the 12 o’clock position, the pins of a 14-pin IC are numbered 1 through 7 down the left side and 8 through 14 up the right side. [01]

When you are working on the underside of the board, you count IC pins clockwise. Pin 1 is just right of the notch on the IC. [02]

Monitor ROM (ROM)

001 - Can I use a 8K EPROM in a Kaypro 10 ('83) which has a 4K EPROM socket?

Yes, you can. Just make your own 4K to 8K adapter.

002 - 002 - What third party monitor ROMs can you use on the Kaypro's?

On the Kaypro 10, the Advent TurboROM is my first choice. Otherwise, my recommendation goes to the ROM's from Micro Cornucopia.

003 - How can I save the monitor ROM to a file?

There are two variants to choose from here. Variant 1 is fast and easy, but you need an additional standalone program, e.g. GETROM24.COM for the Kaypro II/2/4. For the variant 2 you don't need an additional program, because it works with DDT.COM. But you have a little bit of typing. Both variants have their advantages and disadvantages.
Variant 1

You need the programs: GETROM24.COM, GETROM84.COM or GETROM10.COM. All available from the internet (KPGTROM.ZIP - www.retroarchive.org).

Variant 2

Use at your own risk! Douglas Miller posted the following in the KAYPRO USERS GROUP in Facebook. So far (12/2022) I have tested only saving the 2K ROM. The result (GETROM24 vs. DDT) is identical.


----------------------------------------------
| Kaypro:      all '83 models, II/2/4        |
| System port: 1Ch                           |
| ROM size:    2K or 800h                    |
----------------------------------------------
| for 4K (1000h) ROM's use:                  |
|   lxi b,1000                               |
|   m8000,9000,0100                          |
|   save 16 rom.bin                          |
----------------------------------------------

KAYPRO II 64k CP/M vers 2.2

A>ddt
DDT VERS 2.2 
-aa000
A000 di
A001 in 1c 
A003 ori 80 
A005 out 1c 
A007 lxi h,0 
A00A lxi d,8000 
A00D lxi b,800 
A010 mov a,m 
A011 stax d 
A012 inx h 
A013 inx d 
A014 dcx b 
A015 mov a,b 
A016 ora c 
A017 jnz a010 
A01A in 1c 
A01C ani 7f 
A01E out 1c 
A020 ei
A021 rst 7 
A022 (cr) 
-ga000
*A021 
-m8000,8800,0100
-g0

Warm Boot

A>save 8 rom.bin 
A>

----------------------------------------------
| Kaypro:      all '84 models and 10('83)    |
| System port: 14h                           |
| ROM size:    4K or 1000h                   |
----------------------------------------------
| for 8K (2000h) ROM's use:                  |
|   lxi b,2000                               |
|   m8000,a000,0100                          |
|   save 32 rom.bin                          |
----------------------------------------------
KAYPRO IV 64k CP/M vers 2.2

A>ddt
DDT VERS 2.2 
-aa000
A000 di
A001 in 14 
A003 ori 80 
A005 out 14 
A007 lxi h,0 
A00A lxi d,8000 
A00D lxi b,1000 
A010 mov a,m 
A011 stax d 
A012 inx h 
A013 inx d 
A014 dcx b 
A015 mov a,b 
A016 ora c 
A017 jnz a010 
A01A in 14
A01C ani 7f 
A01E out 14 
A020 ei
A021 rst 7 
A022 (cr) 
-ga000
*A021 
-m8000,9000,0100
-g0

Warm Boot

A>save 16 rom.bin 
A>

Character ROM Generator (CHR)

001 - How can I switch ON/OFF the GREEK character generator ROM by Micro Cornucopia?

Access the GREEK characters set with ESC-G and go back to regular set with ESC-A. You do not need a WARMBOOT.

I/O Interfaces (IO)

001 - What can I do with light pen interface on the Kaypro 10?

According to PROFILES 09/1986 page 12 you can do nothing with this interface. The light pen interface was never implemented.

File Management (FLM)

001 - How can I copy or format a single-sided floppy disk in a double-sided disk drive?

For this purpose Kaypro offers the program SSCOPY.COM. You can find this in the Don Maslin archive in the file KP483.ZIP.

002 - Can I read/write or copy a single-sided floppy disk in a double-sided disk drive?

Yes, you can. But it is very important that make a WARMBOOT after inserting a single-sided floppy disk in drive B. During a WARMBOOT, the operating system checks both drives and makes an internal note because single-sided disks are to be handled differently than double-sided ones. As a user, however, you will not notice this.
Dear KUG,

it seems that single-sided discs cannot be copied out of drive A on a Kaypro IV because it looks for track 2 on the second side, and when it cannot find it comes up with an error message. The procedure below works beautifully, so I thought I'd pass it on for future reference in case other Kaypro IV users have problems copying SS discs.

PROCEDURE FOR MAKING WORKING DISC COPIES ON KAYPRO IV FROM MASTERS ON SINGLE-SIDED DISCS

1) Place your Kaypro IV CP/M disc in drive A and boot up.
2) Place a blank disc in drive B and format it.
3) Copy PIP.COM onto disc in drive B plus CP/M to make it bootable.
4) Remove CP/M disc from drive A and replace with disc from drive B.
5) Reset (cold boot).
6) Place single-sided master disc in single-sided drive B [and make a warm boot].
7) Type PIP and hit return.
8) After * prompt comes on screen type: A:=B:*.*[V] and hit return. That's it. It will PIP over in the usual manner without trouble.

Alan True, P.O. Box 10148, Marina del Rey, CA 90295
Kugram Vol 2 No 6 - SS and DS floppy disks
Kugram Vol 4 No 1 - SS and DS floppy disks

Troubleshooting (TRB)

001 - I have a heat problem with my Kaypro II! What can I do?

Especially with the older Kaypro II, heat problems can occur, especially in summer. An additional fan is difficult to install because there is no cutout for it like on the later models.
According to Micro Cornucopia #issue 10, February 1983, page 26 you can eliminate 99% of the problems related to heat by replacing the Z80, the SIO, PIOs, 1793, and the ROMs with better parts (higher speed).

General (GEN)

001 - What (Kaypro) is "Darth Vader's lunchbox"?

No, it is not the black Kaypro Robie. According to Kevin Strehlo, InfoWorld, 07/01/1985, page 8: "Although the Kaypro's boxy, metal construction has resulted in its being derisivly likened to Darth Vader's lunch box." The name thus stands for the rectangular metal boxes, the so-called luggables (Kaypro II, 4, ...). It has nothing to do with the "black" color!

002 - With the Kaypro 10, do I have to park the hard disk before switching it off?

No, you need not. According to Micro Cornucopia issue 14, Oct 1983, page 21, the head of the hard disk is parked in the savety area any time the red "in-use" light is off. Just wait a little and you are done.

Reference

  1. (↑) https://www.dummies.com/article/technology/electronics/general-electronics/electronics-integrated-circuit-ic-pinouts-142469/
  2. (↑) Micro Cornucopia, Number 15, December 1983, page 14
  3. (↑) (Kaypro) Disk Drive Diagnostic Users Guide, May 1984 pages 10-3, 10-5
  4. (↑) David Katz, Facebook Kaypro Users Group

My Series About the KAYPRO

--> Go to Part 0 : Information
--> Go to Part 1 : Versions
--> Go to Part 2 : Hardware
--> Go to Part 3 : 8K EPROM Modification
--> Go to Part 4 : Formatting a Hard Disk
--> Go to Part 5 : USER areas
--> Go to Part 6 : MASMENU - Master Menu
--> Go to Part 7 : Terminal
--> Go to Part 8 : KayPLUS ROM
--> Go to Part 9 : Advent TurboROM
--> Go to Part 10: Multicopy Plu*Perfect
--> Go to Part 11: The Kay Family & Company
--> Go to Part 12: Kaypro Design Views
--> Go to Part 13: Micro Cornucopia
--> Go to Part 14: Repairing a Kaypro II
--> Go to Part 15: Kaypro Collections
--> Go to Part 16: Kaypro General
--> Go to Part 17: Kaypro Robie
--> Go to Part 18: MFM-Emulators
--> Go to Part 19: Roadrunner ROM
--> Go to Part 20: Software
--> Go to Part 21: FAQ
--> Go to Part 22: Kaypro Virtual
--> Go to Part 23: Formatting a Floppy Disk
--> Go to Part 24: ROM, EPROM
--> Go to Part 25: Kaycomp