Intel 8748 uC programming with Arduino

[TimInCanada]

In case this is of use to anyone else.  Programming a 8748 is most likely done to repair something, which is why this is being posted in Repair.

I needed to program a 8748 to replace a dead 8048 (mask programmed version), but the 8748 uses programming voltages that are not available with inexpensive EPROM programmers.  So, Arudino to the rescue.

Attached is the program.  See the datasheet for wiring of the 8748.  Note that this program and voltages listed are for the 8748H version of the chip.  Voltages are different for the regular version, but double check the programming sequence is the same, too.

The data to be written to the uC is in a byte array of hexadecimal values.  By using the PROGMEM key word, this array is stored in the Arduino's flash memory so that a 2Kbyte 8749 can be programmed as well.

There is also a schematic for the transistor switches I used.  There are probably better circuits, but these worked.  The EA signal switches between 5 and 18 volts, the VDD between 5 and 21 and the PROG between floating and 18.  I used three bench supplies and adjusted the input voltages so the outputs were 5, 18 and 21 after the transistor and diode voltage drops.  The 1K resistors to ground are to ensure there is enough current flow that the diodes are fully on.

The program follows the datasheet instructions exactly and verifies each byte after it is written.  The program ends with a message programming either worked or it didn't.

Tim

[saturnin]

I needed to program a 8748 to replace a dead 8048 (mask programmed version), but the 8748 uses programming voltages that are not available with inexpensive EPROM programmers.  So, Arudino to the rescue.

FYI. I successfully used Willem EPROM Programmer to program i8748 some time ago (all documentation needed to build one is here: http://www.mpu51.com/eprom/eprom.html). It worked perfectly, though I had to use an adapter, because Willem Programmer does not have appropriate socket for 8748. I admit it is rather old programmer and its usage is little bit cumbersome nowadays since it requires LPT port...

[SaabFAN]

I did build such a programmer with a Arduino Nano to repair my PM6654C counter.

It is relatively easy to build on vero-board: https://www.eevblog.com/forum/microcontrollers/simple-programmer-for-vintage-intel-mcs-48-microcontroller/msg975681/#msg975681

Edit: And by looking at the program, I see you found it already 

When I wrote my Arduino-Sketch for this, I didn't know about the PROGMEM-Option, so I wasn't able to program anything bigger than 1k.

[TimInCanada]

Hi SaabFAN,

Yes, thank you for posting your solution.  I had started with your code and the MCS-48 handbook, and by the time I had figured it out and got it working, there wasn't much original code left.  Primarily because of my (often slow) learning curve. 

Tim

[DreaDNoughT1666]

Hi TimInCanada,
I needed to get a philips g7400 back up and running and I came across your project that I built (and burned up one 8748H because i flipped the PNP transistors the wrong way around whoops)
And i just wanted to ask if you are sure that the d8748 has different programming power than the D8748H, because from (the little ammount) of information that I can gather, they're both the same ?
it's just that the D8748H version seem to be Cmos (or Hmos) and the D8748 seems to be NMOS.