The next board in the system is called the buffer board. This board is the interface between the personality board and the long cable that goes to the interface pod. The board buffers the signals for the long run through the cable.
The component side is mainly 74 series line drivers and DIP resistor packs. The four connectors on the left are for the interface pod cable.
The back of the board has the connectors that connect to the personality board.
The next board we are going to look at is the Personality Board. Unlike the Brain Board which is common to all version of the development system, there is a different Personality Board for each processor.
The databook lists the following details for this board:
“The Personality Board consists of a firmware Monitor, 16k bytes of shared memory,
2k x 48 Trace memory, Port recreation logic to recapture the pins used for emulation, emulation hardware, and an In System Emulator, ISE, cable.
Up to eight external events as well as 16-bit address and 16-bit data busses can be traced in the 2k deep trace memory.”
A,B – MCM2018AN45 – 2048 x 8 static RAM
C – AM27512 – 64K x 8 EPROM
D – Brain board connectors
E – This 40 pin socket seems to have been intentionally left empty. Not sure what purpose it served.
F – This is where the buffer board plugs in which connects to the interface pod.
G – (4) MCM2018AN45 – 2048 x 8 static RAM
H - TC55464 – 64K x 4 static RAM
I – (3) MCM2018AN45 – 2048 x 8 static RAM
J – (2) 71256 – 32K x 8 static RAM
K – Power connector
On the back of the board you will see a bunch of wire-wrap wires. These are manufacturing modifications to the board. When design problems were found with boards it wasn’t always economical to create a new PCB so it was quite common for modifications like this to be done during the manufacturing process. Most of these wires connect back to a EP8201 delay line IC that was added to the board. A delay line has one input and multiple outputs the delay the signal be specific amounts of time. Based on this they probably found a timing issue with parts of the circuit so had to make the modification to alter the timing.
Below is a picture for the Brain Board. As I explained in my last post there was a common Brain Board that was used across the different variations of the development system.
Along the left side are the three serial connectors that provide the user interface to the system. At the bottom is 5 pin power connector and a three pin connector that goes to the reset switch on the front panel. At the top are two connector (on the back side of the board) that connect it to the Personality Board. There are spots for two pairs of connectors but only one pair is populated.
I have labeled the major chips on the board.
A. Four 2764, 8K EPROMS for a total of 32K or ROM.
B. Intel 8253 programmable interval timer.
C. Eight, 4164, 64Kx1 DRAM for a total ok 64K RAM.
D. National Semiconductor NSC800N CPU. This is National’s version of the Z80.
E. Three Signetics 2561 Programmable Communication Interface, one or each serial port.
F. This ZIF socket is for the EPROM programmers. There is a ribbon cable that connects it to the ZIF socket on the front panel. I am not sure why they spent the money for a ZIF connector on the inside.
Most of the rest of the board is 74 series logic and a couple PALs. There is one odd chip labeled 8188-U40. U40 is it’s location on the board so I assume it’s some sort of custom chip.It is near the EPROM programmer so might be part of that circuit.
Here is a look inside the system’s case. When you remove the side panels if reveals two compartments, once on each side. The first side contains a off the shelf switching power supply which provides a range of voltages to the the system.
On the other side of the case are the logic boards. National made three variations of this developments system. The one I am showing here is for the HPC processors, and there were also versions for the COP400 and COP800 microcontrollers. The large board on top is called the brain board and is common to all three versions of the system. The brain board has the microprocessors and supporting hardware that provides the user interface to the system. Underneath the brain board in the personality board which provides all the target processor specific hardware. There were three different versions of the personality board, one for each target processor. The small board in the bottom left is the brain buffer board which has the electrical buffering between the brain board and the interface pod. I believe this board is also unique to each target processor.
In my last post I introduced the HPC Microcontroller Development System from National Semiconductor. Lets take a closer look at the outside.
Here is the product information label
Serial Number: HK1193
Part No: 970420191-1
Voltage: 115/230 VAC
Amperes: 60Hz 3A
Model No. HPC-DEV-ISE 1
Here is the back panel. On the fight is the fan, product label power switch and power outlet. On the left are connectors for three serial ports. One of these would be used for a terminal to access the internal software. This could be dumb terminal bus was often a host computer where software could be compiled and downloaded to the device. The others ports could be used to connect a printer, and also to connect to other dev systems. You might do this if you were developing a device that had multiple HPC processors.
On the front panel you can see two switches, one resets the development system. The other switch is related to the ZIF (Zero Insertion Force) socket on the front panel which is an EPROM programmer. The switch is used to change the programming voltage for the EPROM. At the bottom of the front panel is the cable going to the processor interface pod.
Here is a look at the processor interface pod. On the right side is a PCB with a PLCC connector on the bottom that plugs into the socket where the processor goes. I am not 100% sure what the other four connectors are for. The databook for the system mentions “eight external event inputs” and the ability to trace and breakpoint on external events. It also mentions “trigger output for logic analyzer”. I assume the connectors are used to support these functions.
A while back I acquired this interesting piece of hardware. I knew it was an in circuit emulator (ICE) but didn’t know much more about it. In this and upcoming posts I plan to take a detailed look at this device.
An ICE is a device used in the development of microprocessor based systems. It plugs in in place of the microprocessor/microcontroller and allows software to be transferred to the system under development from a host system. It also normally has a series of debugging features, for example the ability to single step code, view and edit memory, set break points, etc.
This particular ICE is for the National Semiconductor HPC series microcontroller. The HPC series was released in the late 80’s and was a 16 bit microcontroller with on-chip RAM, ROM and various peripherals.
You can find information about this processer in the databook on Bitsavers: