24 Mar
2017
24 Mar
'17
11:06 a.m.
On Mar 24, 2017, at 12:44 PM, Noel Chiappa via cctalk
<cctalk at classiccmp.org> wrote:
So all the DEUNA's I've seen have L10 (ceramic package, 10Mhz) 68K's in
them.
Has anyone tried using anything else, and did it work?
I _assume_ an x12 would work, but until someone has acutally tried it...
The Pxx's (plastic packaging) might not work - according to the datasheet,
they are 2mm wider than the ceramics (why, I have no idea - it probably means
they aren't interchangeable, which makes no sense at all to me).
I looked at the 68000 User Manual on the NXP website, which has package dimensions in
chapter 11: http://www.nxp.com/assets/documents/data/en/reference-manuals/MC68000UM.pdf
It shows two 48-pin packages (ceramic and plastic). The package bodies are not the same
width, but that is irrelevant. The dimension that matters is the pin spacing (dimension
"L" in those drawings) which is 0.600 inches in both cases. Similarly, the 64
pin packages have different body width but the same lead spacing (0.900 inches).
The reason the body widths differ is that in the plastic package, the pins come out
horizontally and are then bent down outside the body, so the bend radius adds to the pin
spacing. In the ceramic package, the pins are brazed to the sides of the body, so those
extra radii are absent.
So my conclusion is that the plastic parts will fit. Which makes sense; DIP packages
(independent of material) are designed to a small set of standard dimensions. 0.1 inch
lead pitch, pin spacing 0.300 or 0.400 or 0.600 or similar round numbers.
paul