rtm1@thumper.bellcore.com (Ravi Masand) (12/11/88)
A question for the hardware hackers out there: Do you have any information as to whether the transputer (T414, say) can be slowed down by dropping its CLKIN frequency from the rated 5 MHz ?? The data sheet does not specify any limits on this frequency - just a nominal value of 5 MHz - No Min, No Max! I suspect that there is a limit to how slow one can go as the internal PLL will be unable to lock below a minimum CLKIN. Which brings up another question - can the internal PLL be bypassed ? I know, from looking at some old Inmos schematics, that this was possible with older versions of the chips. Does the current version support this (as an undocumented feature perhaps ) ?? And just what are those "HoldToGround" pins ?? Thank You. Ravi Masand thumper!rtm1 P.S. This is the second time I'm posting this - the first time, i suspect, it turned to vaporware. If not, I Apologize.
w-colinp@microsoft.UUCP (Colin Plumb) (12/12/88)
In article <1407@thumper.bellcore.com> rtm1@thumper.bellcore.com (Ravi Masand) writes: >And just what are those "HoldToGround" pins ?? Mostly "reserved" pins, so T8's are plug-compatible with T4's, as are T425's. One pin I know exists on the T414, which may not be documented for that chip, (it isn't on the T8) is E1, which diasbles internal RAM (useful for debugging) when pulled high. On the T8, you can use the Proc Speed Select pins to select 17.5 MHz, but I don't know about going any lower. On the T425, A1 and B3 (Do Not Wire on the T8) are outputs, Refresh Pending (used to pause external DMA to allow a memory refresh, high indicates the transputer would like to do a refresh cycle), and Event Waiting (which is pulled high when a process is waiting on the event channel; it goes low when Event Ack goes high). I don't have a T414 data sheet, so I can't compare and see what was added on the T800. >P.S. This is the second time I'm posting this - the first time, i suspect, >it turned to vaporware. If not, I Apologize. I didn't see it. -- -Colin (uunet!microsof!w-colinp)