HEKTOR PT502 8085 machine

[RayS666]

I have been restoring one of these machines and run into a problem...

After getting past the broken pins, dry joints, and bad IC sockets I have it narrowed down to 2 of the roms, the HEK1A SKT1 (2732) is blank, and the 2716 in IC5 has patches of &FF in 0100-01FF & 0400-04FF, I am not sure this is right though it could be by design. I really need a dump of each of the ROMS HEK1A SKT0, HEK1A SKT1 and IC5 if anyone has them.

 

[RingingResonance]

You may not have the correct enable pins at the right state when reading the first ROM. Care to post the dump of the second ROM? Do you have a way to program a new ROM with a test program to make sure the hardware is working?

 

[RayS666]

You may not have the correct enable pins at the right state when reading the first ROM. Care to post the dump of the second ROM? Do you have a way to program a new ROM with a test program to make sure the hardware is working?

Hi, thanks for the input..
the story so far... the rom in skt1 was blank, not only blank but unprogrammable even after UV. when i burned a new copy it would boot but be in perpetual 'break point' mode until the stack full caused a reset. I traced this to a 'misbehaving rom0, looked ok in the burner but i occasionally saw one of the data lines glitching, anyway a newly burned copy cured this. now it boots to monitor but the keyboard is unresponsive. keyboard electrically tests ok but 2 of the pins of the 8155 that strobe the kbd matrix are always at '1'. I manually powered the 8155 in a breadboard and they are the same so I have ordered a replacement. I manually tested the fprom address decoder and it maps out ok (nothing like the mapping on p96 of the user guide but mine is a HEKTOR 1 and it looks like the guide was rewritten for the H2). You mentioned a test program, does one exist?

 

[RingingResonance]

Hi, thanks for the input..
the story so far... the rom in skt1 was blank, not only blank but unprogrammable even after UV. when i burned a new copy it would boot but be in perpetual 'break point' mode until the stack full caused a reset. I traced this to a 'misbehaving rom0, looked ok in the burner but i occasionally saw one of the data lines glitching, anyway a newly burned copy cured this. now it boots to monitor but the keyboard is unresponsive. keyboard electrically tests ok but 2 of the pins of the 8155 that strobe the kbd matrix are always at '1'. I manually powered the 8155 in a breadboard and they are the same so I have ordered a replacement. I manually tested the fprom address decoder and it maps out ok (nothing like the mapping on p96 of the user guide but mine is a HEKTOR 1 and it looks like the guide was rewritten for the H2). You mentioned a test program, does one exist?

I wrote my own test program. Try it out. https://github.com/RingingResonance/8085debugger

 

[RingingResonance]

Hi, thanks for the input..
the story so far... the rom in skt1 was blank, not only blank but unprogrammable even after UV. when i burned a new copy it would boot but be in perpetual 'break point' mode until the stack full caused a reset. I traced this to a 'misbehaving rom0, looked ok in the burner but i occasionally saw one of the data lines glitching, anyway a newly burned copy cured this. now it boots to monitor but the keyboard is unresponsive. keyboard electrically tests ok but 2 of the pins of the 8155 that strobe the kbd matrix are always at '1'. I manually powered the 8155 in a breadboard and they are the same so I have ordered a replacement. I manually tested the fprom address decoder and it maps out ok (nothing like the mapping on p96 of the user guide but mine is a HEKTOR 1 and it looks like the guide was rewritten for the H2). You mentioned a test program, does one exist?

I forgot to mention. Some of those older ROMs take higher voltages to program. The 2716's takes 23v 25v on the program pin to get them to program and you have to be kinda slow as well. I suggest getting a 40 pin ZIF socket, bending it's programming pin out so you can solder to it, and then solder to the ground pin as well so you have a place to connect a higher voltage power supply. It's how I've been programming 2716's with my little MiniPro.

As for not erasing, there could be an invisible layer of contamination on the window. Try cleaning it with some rubbing alcohol; Really scrub it with a q-tip when you do just be careful not to bend your pins. I had a problem with one byte not completely erasing on one of mine. It wasn't until I cleaned it that it would erase.