Recent content by richterh

Many thanks for your help. For now I'm happy with my working PET. The tape drive is a separate issue that I will address next. Harald

Hello Dave, great, fix the interruption and got the blinking cursor back. I'm just surprised about the scratch because I didn't make it. maybe there was some connection at the beginning that was interrupted by the warmer circuit board. Thanks for your help. I'm sorry that you spent a lot of...

Hi Dave, the CS2 signal is missing. I recognize a strange scratch on the board interrupting on of the lines. Not sure if it is the CS2 signal but it looks like it. I try to repair the connection. Harald

Thank you Dave

I have a small Hameg HM103 oscilloscope with one channel. I can see the long pulses with short pauses on all 16 outputs and the pulses with different frequencies on the 4 inputs. Harald

Hi Dave, E2 and E3 are hidden under the ROMulator, I can’t reach to the pins. Got the signals at J4, pin1,2,3… with 250kHz, 125kHz… BA9 = 500Hz, BA10=250Hz, BA11=125Hz, BA12=60Hz, BA13=30Hz, BA14=15Hz, BA15=7,5Hz Harald

Hi Dave, I checked the PIA keyboard connection. all 10 connections (J5, 1-10) from the keyboard to the 74145 switch from 0V to 5V when the fitting key is pressed. the 4 connections from 74145 to PIA are all permanently high, no response to keystrokes. Without PIA, the level on the 74145 is...

Hi Dave, the PIA was installed during the test. I can examine the path from the PIA to the keyboard. maybe the 74145 has an error. Harald

I now have a broken pin on the socket between the ROMulator and the board. Have to get a new socket first...

I have 1 PIA and 1 VIA as spares but I get the same result with all of them. The high level at CPU pin 4 is also without all PIAs and VIA and even without CPU. Where else can it come from? I can't see any other source on the schematic. Harald

my fault, there is no cursor, I just get the screen with *** COMMODORE BASIC ***,or ### COMMODORE BASIC### Harald

and with setting #2, basic 2

The ROMulator works with setting #9, Basic 1

Pin 18 has about 60hz pulses

Have swapped the PIA, still high level on CPU pin 4