Looking at the schematic for the TPDD, it would appear that the TPDD is not true RS232. It is only swinging between 0v and 5v with voltages outside of that range being shunted to gnd/vcc via diodes. The model 100 on the other hand appears to use vee/vcc voltage swings that are probably RS232 compliant or at least closer to what they should be.
I could use a MAX232 chip and loop the RX and TX lines through it to regenerate the signals.might try that over the weekend. From: M100 [mailto:[email protected]] On Behalf Of Gary Hammond Sent: Wednesday, 17 August 2016 8:28 PM To: 'Model 100 Discussion' <[email protected]> Subject: [M100] TPDD/TPDD2 boot disk captures (Take 2) . I have not yet succeeded in capturing the TPDD backup of the boot disk. There is just enough bleed to the serial sniffer to stop the backup process commencing after the destination disk has been formatted. The backup program hangs at the end of the format routine and there is no disk activity after the heads return to the start position. Normally there looks like a head seek to read a directory at the end of the format. If I take the serial sniffer out of the circuit, the backup process works fine. I have tried with 2 different TPDD's and I get the same result. Maybe the serial com circuit is more sensitive in the TPDD's. I may need to make up an external serial buffer to boost the RS-232 levels. .
