This section is a collection of procedures, methods and how-to's around the 9845 series. Many procedures are concerned with repair and troubleshooting issues, just because most systems are in a condition which requires special care. Others are dealing with preservation tasks or describe how to bridge 9845 with standard PCs or with each other.

I try to make those tutorials as demonstrative as possible and give step-by-step guidance, however it requires some effort always to include appropriate illustrations and to make everything bullet-proof. So please take the chance and make suggestions if something doesn't work as described or can be done better.

Currently this page is mainly a collection of my own experiences, but I'm looking forward for contributions.

Before First Turning On Before First Turning On

Just in case a 9845 system has just been aquired, it it has not been switched on for a reasonable period of time, some precautions schould be considered in order not to loose your system with the first power-up. Those 9845 systems can have a history of 30 years, and some components may silently have gone instable during that time.

Troubleshooting Troubleshooting

The more complex a system is, the higher is the chance that anything won't work. This section tries to give some advice on how to get a basic feeling where a problem may be located, and how to further isolate and even find a solution for a fault. However, this section is still heavily under construction.

Saving Tapes Saving Tapes

One of the most important preservation tasks is to get programs and data off the tapes. Most remaining tapes are already partly defective, and the same is true for most internal tape cartridge drives. Nevertheless the software is an important part of the story, and there are ways to preserve at least as much as there can be reconstructed.

Dumping ROMs

Dumping ROMs

Due to the growing instability of the ROMs no time should be wasted in saving at least the ROM contents. This is especially important for the systems ROMs, however also the option ROMs will sooner or later be subject to decay. This section describes how to get the data out of both types of ROMs and how to store it in a proper format.

Connecting to the PC Connecting to the PC

Anyone working with vintage systems probably knows abount the importance of a working connection between the vintage system and a standard PC. The same is true for a 9845 system. Data can be transferred from a 9845 to a PC, where a much better environment is available to perform deeper analysis and create a long-term storage for the information. On the other side, data and programs can be prepared with all the possibilities of a standard PC and then transferred to the 9845 for operation.

Tape Drive Repair Tape Drive Repair

The 9845 internal tape drive has proven to be one of the weak points of the 9845 system. Once extremely reliable, it suffers more than most other components from the ravages of time. Almost all tape cartridge drives have a "melted" capstan rubber coating, and there are many other things which can go wrong with the tape drives. This section covers most of those issues.

RAM Repair RAM Repair

After the system ROMs the DRAMs are probably the next most frequent source for system freezes. Fortunately, the 9845 series already used standard DRAMs, so they genarally can be replaced without too much effort. Most of the work is identifying the bad chip, getting a new one and unsoldering the defective chip from the PCB (none of the DRAMs was socketed).

9845 Networks 9845 Networks

What would be a workstation without shared network resources. Although the initial concept of the 9845 was that of a high-performance standalone workplace computer, there are several solutions how to integrate 9845 systems in minicomputer environments, and how to set-up a network-based shared resource management and peer-to-peer networks.

Using Bitmaps Using Bitmaps

The 9845 systems were perfect graphics engines, at least compared to other systems of the time. This tutorial tells more about how the data can be captured from the screen, converted to a standard Windows BMP format, and all the way back.

9845 Game Design Tutorial on 9845 Game Design

Programming games makes fun on all platforms, if you know how to get the best out of it. Here are some basics on game design in general and hints on implementation on a HP 9845. As a sample implementation, the adoption of the well known Space Invaders is introduced.

9845 Test ROM and Test Binary 9845 Test ROM and Test Binary

For all kind of troubleshooting, using the diagnostics provided by HP itself is the way to start. Whereas the Test Binary checks system components with minor relevance (including peripheral devices), the Test ROM provides diagnostics on the core components (CPUs, system memory) and the built-in tape drives. The Test ROM sometimes even works if the system does not boot up at all.

Using Logic Analyzers

Using Logic Analyzers

In-depths system analysis needs the use of a logic analyzer. Especially if all other diagnostic means fail. This tutorial shows how to troubleshoot and even trace instruction processing on a HP 9845 system in real time with a low-cost logic analyzer.


Tutorial on the Hewlett-Packard Interface Bus (HP-IB)

Everything you always wanted to know about the HP-IB/GPIB/IEEE-488/IEC625, about history, relevance, functional and technical basics and how it is today.