Infotron Systems IF-65

 

Back in the late 80's and early 90's I worked for Infotron Systems (later Gandalf Technologies) which manufactured data communications equipment. A lot of Infotron’s equipment was based on the 6502 microprocessor, so much so that they designed and manufactured their own 6502 in circuit emulator (ICE) the IF65. The IF65 was a great tool for both developing embedded 6502 software and for troubleshooting 6502 hardware. The IF65 was mainly used in house, but I know of at least one other company that Infotron sold them to. Fortunately, I ran across a working IF65 at a flea market a long time ago.


The built in monitor software is accessed through a serial terminal. The monitor provides functions to read/write memory, test RAM, assemble and disassemble code, and access the EPROM programmer.

I worked in the repair department, initially doing manufacturing repair and then eventually customer return repairs. We used the IF65 to run special test programs and as a general troubleshooting tool for 6502 based boards. This version of the IF65 has 64K of static RAM that can be configured to overlay the product's memory in 4K blocks. You would normally set this up to overlay the ROM portion of the product's memory map. Code could then be loaded by reading it from an EPROM using the EPROM programmers, downloaded from a host computer (we used VAX mainframes at Infotron), or even entered using a built in line assembler.

A really useful feature for troubleshooting was the address trap function. If, for example, you wanted to troubleshoot the address decoding hardware you would set the trap address to the address you were trying to test and then set the switches for read, write, and/or opcode access. Now any time that address is accessed you would get a sync pulse output through the connector on the lower right side. You would hook this signal to one channel of an oscilloscope and then use the other channel to probe the circuit and you would see what a signal state was as the moment the memory access was happening. 

Another feature that comes in really handy for running test software is the ability of the 6502 code to access the serial ports on the IF65. This allows the test software to interact with the user even if the unit under test is totally non-functional. This functionality, when enabled, is accessed with the 6502 BRK instruction. The byte after the BRK command contains the command you want to execute and the Accumulator is used to pass data. For example, to print a character you would do this:

LDA #$30

BRK

.BYTE #$11