The Zenith H89
This appears to be quite a rare machine these days, it was manufactured by Heathkit who were taken over by Zenith, the machine and documentation are both badged heathkit and Zenith . The H89 was a modular machine and could be configured to suit your needs. As you can see from the Photo it was an all in one computer, one of the unusual features of this machine is that it has 2 Z80 processors, one for the computing functions and the second for the terminal operations.
Below are the specifications taken from the operations manual.
Specifications
| CPU AND MEMORY | |
| Processor............................ | Z-80 |
| Clock................................... | 2.048MHz |
| Memory.............................. | 16K bytes user RAM (expandable to 48K) |
| 8K System for ROM and RAM | |
| 8K reserved | |
| Display | |
| CRT.................................... | 12" diagonal, P4 phosphor. |
| Display Format................... | 24 lines of 80 Characters ( with access to 25th line). |
| Display Size........................ | 6.5" high x 8.5" wide. |
| Character Size.................... | 0.2" high x 0.1" wide (approximate) |
| Character Type.................. | 5 x 7 dot matrix (upper case) ; 5 x 9 (dot matrix lower case with
descenders);
8 x 10 dot matrix (graphic). |
| Keyboard............................ | 84 Keys (60 alphanumeric, 12 function/control) plus a 12-key numeric control pad. |
| Cursor................................. | Blinking, nondestructive underline. |
| Cursor Controls.................. | Up, down, left, right, home, CR, LF, back space, tab and cursor off. |
| Cursor Addressing............. | Relative and direct. |
| Tab...................................... | Standard 8 column tab. |
| Refresh Rate...................... | 60 Hz 60 Hz/50Hz at 50Hz line frequency |
| Edit Function....................... | Insert and delete character or line |
| Erase Function.................... | Erase page, erase to end of line and erase to end of page |
| Bell...................................... | Audible alarm on receipt of ASCII BEL. |
| Video................................... | Normal and reverse by character |
Finally I would like to thank Steve Bell for donating this machine and a mountain of documentation.