Heathkit H89/H19 Automatic Key Repeat Board

[Jeff Tranter]

The lack of automatic key repeat on the H89 and H19 is a little annoying when you are used to this feature on modern computers. In the 1980s, Analytical Products sold a kit for a little board that connected between the keyboard and terminal logic board that added automatic key repeat. I've never seen an original unit, but the manual has a schematic and instructions that were enough to reproduce the board. I designed a PCB and constructed it and it works very well. It goes inline between the keyboard and ribbon cable so no modifications to the computer are needed and it should work with the H89, H89A, H19, and H19A (I have an H89).

I'll post more details at some point on my blog and/or YouTube, but the information here (including PCB Gerber files) should be sufficient to build one if you want: https://github.com/jefftranter/Z80/tree/master/AutoRepeatModule

[Joseph Travis]

Very cool Jeff!  'Any plans for videos of your H89 adventures?

Joe

On Mon, Jan 13, 2025, 5:58 PM Jeff Tranter <tra...@gmail.com> wrote:

The lack of automatic key repeat on the H89 and H19 is a little annoying when you are used to this feature on modern computers. In the 1980s, Analytical Products sold a kit for a little board that connected between the keyboard and terminal logic board that added automatic key repeat. I've never seen an original unit, but the manual has a schematic and instructions that were enough to reproduce the board. I designed a PCB and constructed it and it works very well. It goes inline between the keyboard and ribbon cable so no modifications to the computer are needed and it should work with the H89, H89A, H19, and H19A (I have an H89).

I'll post more details at some point on my blog and/or YouTube, but the information here (including PCB Gerber files) should be sufficient to build one if you want: https://github.com/jefftranter/Z80/tree/master/AutoRepeatModule

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[Jeff Tranter]

Yes, I plan to make a series of YouTube videos later this year.

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[Lee Hart]

There was also an auto-repeat circuit that just involved adding a few parts to the TLB. I added it to one of my H19s. The circuit was probably in one of the Heath magazines, REMark or Sextant. As I recall, it was a transistor, a couple resistors, and a capacitor. Anyone else remember it?

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[Jeff Tranter]

I found this article which uses 12 diodes, a 74123, a transistor, and some other parts.

It can be built into the keyboard PCB.

http://cpmarchives.classiccmp.org//cpm/Software/WalnutCD/cpm/heath/repeat89.doc

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[Joseph Travis]

The cool thing about the circuit that Jeff chose is that it inserts inline with the keyboard, uses CMOS chips and steals its power from the bus.

Joe

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