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Last revision of this page: December 10, 2024

Basically, Kaypro has used three different ROM sizes over the years: 2K, 4K and 8K; or expressed in EPROMs: 2716, 2732 and 2764.

• Monitor ROM
• Kaypro
• Micro-C by Micro Cornucopia
• Advent TurboROM by Plu*Perfect
• KayPLUS by MICROCode
• Roadrunner by Highland Microkit
• Emerald Microware
• Character ROM
• Kaypro
• Micro Cornucopia

Kaypro

The ROM BIOS's for the Kaypro II, 4 and the Kaypro 10 ('83) were originally written by Gilbert Ohnysty. Read the story about the first BIOS here. In my video chats, David Kay spoke very highly of Gilbert Ohnysty.

I know the following BIOS software developers (in alphabetical order). I have used the time data as they appear in the source code (known to me).

• Hayes, Thomas N.: 03/1984, Kaypro 10
• Fabian, Steven R.: ??.1983, Kaypro 10
• Nickerson, Jim: 07/1982, Kaypro II
• Ohnysty, Gilbert: 05/1982, Kaypro II, 4, 10
• Sherman, Matthew: 12/1983, Kaypro 10

The Kaypro 4 (and the newest Kaypro II) contain a 2732A ROM, which should run any speed you wish. However, if you have one of the older IIs you'll have to replace the monitor ROM. The 2716 monitor ROM (U47) supplied on the older IIs will not run at 4 or 5 MHz. Even if you get one that will run cold, it will no doubt die as the system warms up. As chips get warmer, they get slower. A 2716-1 (350 ns) will run at 4 or 5 MHz. You can copy the contents of your present ROM into a 2716-1 using a standard ROM programmer like a DATA-IO, ... [1]

If you speed up your Kaypro II or 4 to 4 MHz or 5 MHz you need a faster Monitor ROM; 350 ns or faster. The designation will be 2716-1 or 2716-H. Please do not confuse with 2716 F1 (F=FDIP24W; 1=temperature range 0 to 70 degrees).

Kaypro II - 81-149x - 2K - 2716

This is the very first ROM BIOS and it is only used in the 81-110 (A, B1 and B2) mainboards.

While comparing the Kaypro II ROMs (81-149x), I have noticed that the original 81-149 BIOS has a different sign-on message than the B and C versions.

• 81-149:   Please insert your diskette into Drive A
• 81-149A: Please insert your diskette into Drive A
• 81-149B: Please place  your diskette into Drive A
• 81-149C: Please place  your diskette into Drive A

By chance I may have found the 81-149A version (binary code, no photos) on the internet (05/13/2022).

• The A version has the same sign-on message as the 81-149: "Please insert your diskette in Drive A"; not "... place ...".
• The differences between 81-149 and the A version are "only" 232 bytes. Whereas the differences between 81-149 and 81-149B/C are nearly 1,000 bytes.

Ezra Shapiro - David Thompson

In the Facebook group Kaypro Computer Users, the member David Grimshaw has a Kaypro II which (probably) originally belonged to Ezra Shapiro. This is the person who worked as Director of Corporate Communications at NLS/Kaypro in 1982. His Kaypro II contains a monitor ROM, which does not display Kaypro II as the start message, but EZRA SHAPIRO.

The monitor and character ROM bear the © symbol and the signature of David Thompson, the editor of Micro Cornucopia magazine. According to the information I have, the monitor ROM for the Kaypro II was written by Gilbert Ohnysty. David Kay confirmed this to me in an interview in 2022.

This raises the question of what is to be protected by copyright. What changes has David Thompson made to the 81-149 monitor ROM by Kaypro? The situation with the character ROM is a little more complicated. According to David Thompson, Kaypro copied its own ROM written for Tektronix. This can be read in Micro C issues #14 and #15.

The simple name change (to EZRA SHAPIRO) is easy to do and can be made by anyone who has an EPROM burner, but not the other changes. You need the source code for this. I have tested the BIOS, it runs fine.

A comparison in the HEX editor shows that thr Thompson-Shapiro ROM is almost identical to the original ROM 81-149 by Kaypro. This ROM also uses the verb insert, not place, see above.

Kaypro II - 81-232x - 4K - 2732

This is the later BIOS for the Kaypro II and it is used in the 81-240 mainboards; it is also used in the Kaypro 4 ('83). The sign-on message is only KAYPRO, not KAYPRO II or KAYPRO 4, because it is used in both Kaypro's!

For example, Kaypro II with 81-240 mainboards and single-sided Tandon drives were sold. However, the same mainboard was also used in the Kaypro 4 ('83) with double-sided drives.

Kaypro 10 ('83) - 81-302x - 4K - 2732

A customized ROM for the Kaypro 10. I do not have any further information.

Kaypro

In addition to the monitor ROM, the Kaypros also contain the so-called CHARACTER (GENERATOR) ROM. This is actually nothing other than the character set used.

If you want to have a detailed knowledge about the internal coding of the CHARACTER ROM, please have a look at this text file [6]. If you want to create your own character set, read issue 6 of Micro Cornucopia, June 1982.

The following seven CHARACTER ROMS are known to me:

• Kaypro II, 2, 4
1. 81-146
2. 81-146 A
3. Pro-8 GREEK (Micro Cornucopia)
4. Pro-8 CLEAN (Micro Cornucopia)
• Kaypro 10 ('83)
5. 81-187
6. 81-278 A
• UNIVERSAL BOARDS
7. 81-235

Number 1-4 are 2K and 5-7 are 4K.

A simple comparison with a HEX editor and checksum tester shows that no. 5 and 7 (81-187 and 81-235) are identical. No. 6 shows differences (to 5, 7) in the address range 0000-01FF and 0380-03AF. After that, everything up to 0FFF is identical.

Here you will find a tiny 'C' program to read in the 2K CHAR ROM of a Kaypro II and output it as a readable text file. With the help of the Unix program DIFF you can quickly compare two files for differences.

You can also import the text files into a spreadsheet and display and compare the different character sets.

With this tiny BASIC program I printed the respective character set (ASCII 032 to 256).

81-278 A

Here you will find all my gathered information about the CP/M Kaypro's.

1. (↑) Micro Cornucopia, #14, Oct 1983, page 20
2. (↑) Ezra Shapiro Monitor ROM with courtesy by David Grimshaw
3. (↑) Micro Cornucopia, #17, Apr 1984, page 20
4. (↑) Facebook Group - Kaypro Computer Users: John M. Holmes Jr.
5. (↑) eBay sales image
6. (↑) Vintage Computer Federation Forums, member: ldkraemer

--> 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