Joe's HP 5036 Microprocessor Lab web page

Created 10/20/2000

This page still under construction

The HP 5036 Microprocessor Trainer is a 8085 Single Board Computer (SBC) mounted in a brief case. It is used for teaching microprocessor architecture, interfacing techniques, machine language programming and trouble shooting techniques. The 5036 is a completely self contained unit. It has the complete SBC, power cord, power supply and manuals all in a single Samsonite brief case (picture). The manuals and miscellaneous papers are stored in the top. There is even room left over in the bottom to store logic probes, logic pulsers, IC chip clips and other test equipment.

The computer (close up view). includes a 2MHz 8085 CPU, 2K of ROM, 1K of RAM, 26 key keypad, 6 digit LED display, an 8 bit latched output port with individual LEDs on each line and an 8 bit input port with slide switches for each line. Those features are common to most microprocessor trainers but HP went further and provided clearly defined and marked address and data bus lines, each with it's own tiny LED. The six status lines also where clearly marked and labeled and they also had tiny LEDs on each line. This made it easy for the trainee to see exactly what was happening in the computer without having to connect a logic probe to each point. But even that was not enough for the engineers at HP, they also added switches and 12 removable links to allow the user to induce faults in the computer for troubleshooting practice.

The HP 5036 was full of well thought out features including having all of the data lines running adjacent to each other. Ditto for the address lines. That made testing and troubleshooting much easier. Another of it's interesting features of the HP 5036 is that the top lid can be removed from the case and reattached backwards. Then the entire assembly can be stood up like an A-frame (picture) to provide better access to the computer. A supplied strap is used to connect the top and bottom lids so that they don't slid apart. Another handy feature is that the circuit board is hinged and it can be readily released and swung over to expose the bottom side for troubleshooting purposes. The board is locked in it's normal position by a clever push button lock (picture). The button has a mushroom head and is released by pulling the head up slightly. To lock it, the card is pressed down securely against the plastic frame and the mushroom head is pressed down. Simple but effective!

The circuit board also featured two edge connector on the left hand side. These had all of the data, address, status and control lines present and could be used to expand the minimal computer in the 5036. The manual gave full details on how to do this including details of the timing involved.

One of the great things about this trainer is it's outstanding manual, (picture). "Practical Microprocessors". This manual was nearly 500 pages long and not only included all of the training lessons (listed here) for microprocessor programming, interfacing, etc but. also includes sections that teach how to trouble shoot microprocessor based equipment. The troubleshooting portion includes lessons that showed how to use logic probes, logic pulsers, signature analyzers, current probes and even a bit on how to use logic analyzers. The appendices in the back it included a reference chart of 8085 CPU instructions, logic signatures for use with a signature analyzer, a chart that explained logic diagrams, listings for several utility and demonstration programs, the entire ROM listing of the 5036, a section on how to expand the 5035 and data sheets for all of the major ICs used in the 5036 and of course the complete schematics of the 5036. The user lacked for nothing with this system and manual. A service manual (picture) was also available from HP. The service manual included tests and test modes for the 5036 that were not listed in the user's manual. It also had a detailed theory of operation for all of the 5036 circuits. Also included a COMPLETE parts list of all the part used in the 5036 including the vendors name and part number for all of the parts.

The HP 5036 was produced in two versions (picture). The first version was in a thin Samsonite brief case with latches next to the carrying handle. The later version was in a thicker case that had latches on the sides. Both latches on both models are lockable. It's rare to find a 5036 that still has it's keys but I have been able to find a supply of original keys for the old style case and I'm hoping to find some for the new style soon. I'm not sure who made the later one later case but I have confirmed that Samsonite made the earlier one. Most, but not all, of the old style cases have a date code of "1848A" indicating that they were made in the USA during the 48th week of 1978. All of the newer thick style cases that I have seen have a date code of "2212A" indicating that they were made in the USA during the 12th week of 1982. However the date code on limited production items such as these are not completely accurate. Obviously HP didn't just build these for one week in two separate years. The problem is that the serial number tags with the date codes were only manufactured twice. Therefore the date codes indicates when the tags were made and not necessarily when the trainers were made. Both models of the 5036 have exactly the same part number (HP 5036A) and use exactly the same SBCs, books, etc. The only notable difference is the case and the strap the holds the two halves together when it is stood up.

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