Phill Harvey-Smith wrote, on 27/Feb/11 22:57 | Feb27:
On 27/02/2011 21:44, Tony Firshman wrote:
Phill Harvey-Smith wrote, on 27/Feb/11 20:46 | Feb27:
I have a drawing for the bus mouse conversion on Issue III boards.
Looking at the board with QL connector at top:
[snip thanks that's helpfull]
..... and mouse version of ROM needed.
Which are the three missing chips? My diagram is a picture of the top of
the board, and no pcb markings are visible. All the chip labelling
though is visible and it is fully populated.
With the board with QL connector at the top,
1) Third row of chips, I have a 20 pin space between the 74HCT04 and the
ROM/WD1770 positions.
74HC244 - and I now see this is unpopulated on the photocopy I have,
with a white label. I missed it first time round.
2) Below the 74HCT04 and to the left of the 74HCT273 there's a space for
a 14 or 16 pin chip.
Ditto unpop. - and another 74HC74
3) Middle row, below the second 74LS273 there's a space for a 14 pin chip.
Ditto - and 74HC74.
As *all* chips on the board are identically oriented, these three just
have to be as well - ie p1 bottom left. The labelling also suggests
that. Worth double checking though for power and ground.
... so once you get the new Eprom image, you have it!
Tony
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