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Slothie · 13th Jul 2018, 8:55 pm

Pretty much everything is different...
On the DM74S571 the programming voltage is applied to Vcc and the bit being programmed. On the MH74S571 the programming voltage is applied to Vcc and the bit being programmed is brought to 0v, the others being tied to +5v.

The programming pulses are much longer on the MH74S571, (1-20mS as compared to ~1uS) and the algorithm for repeating pulses until programming is achieved is very different. The DM74S571 specifies repeating the programming pulse 5 times after success, whereas the MH74S571 says to stop when success has been achieved, with different pulse widths on each attempt.

13th Jul 2018, 8:55 pm	#35
Slothie Octode Join Date: Apr 2018 Location: Newbury, Berkshire, UK. Posts: 1,287	Re: Tesla MH74S571 programming. Pretty much everything is different... On the DM74S571 the programming voltage is applied to Vcc and the bit being programmed. On the MH74S571 the programming voltage is applied to Vcc and the bit being programmed is brought to 0v, the others being tied to +5v. The programming pulses are much longer on the MH74S571, (1-20mS as compared to ~1uS) and the algorithm for repeating pulses until programming is achieved is very different. The DM74S571 specifies repeating the programming pulse 5 times after success, whereas the MH74S571 says to stop when success has been achieved, with different pulse widths on each attempt.