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Assembly Notes

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David Banks edited this page Mar 29, 2020 · 8 revisions

Introduction

This page covers:

  • Assembling the Atom 8K Ram and Noise Killer Board
  • Preparing the Atom
  • Installation and Initial testing

Assembly

Important: The value of R2 has changed to 1K0. Please double-check you have this.

Start by giving the board a quick clean on both sides with IPA

It's then recommended to assemble in the following order

  • 270R resistor (R1)
  • 1K0 resistor (R2)
  • 10K resistor (R3)
  • 0.1uF axial decoupling capacitors (C1-5)
  • 10 pin SIL male-male header (J1) (just fit J1 at this stage; make sure the pins on the component side won't foul the socket for U1)
  • IC sockets (U1-5)
  • 100pF capacitors (C7,8)
  • C6 (10uF radial) (fitted on it's side)
  • 0.1" headers (LK1-4)
  • This point is a good time to clean the solder side of the board with IPA, as it's less accessible when the remaining headers are fitted.
  • 10 pin SIL male-male header (J2)
  • 9 pin SIL male-male headers (J4,5)
  • 3 pin SIL male-male headers (J3,6)

Preparing the Atom

Remove the following ICs (keep them in a safe place should you wish to revert this upgrade):

  • IC29 (8304)
  • IC30 (74LS138)
  • IC32-IC43 (2114L)

Depending on the length of the header pins on your Noise Killer board, it will probably be necessary to "stack" an additional set of headers between the Atom and the Noise Killer board, to raise it up so that it clears the 6847.

On the Bill of Materials, the "Precidip 64-way turned pin socket strip" is intended to be used for this purpose. Alternatively, you could just insert turned pin IC sockets into ICs 29,30,36 and 37.

Installation and Initial Testing

Do the following:

  • before inserting any ICs, check for shorts between VCC and GND
  • carefully plug board into Atom (it's more stable this way) (the silk screen indicates where it should fit)
  • fit all ICs
  • fit LK1 south (between "new" and nWE)
  • fit LK2 south (between "new" and nOE)
  • fit LK3
  • fit LK4 in one of the settings marked 1 (i.e. between pins 2 and 3)
  • power up the Atom
  • press BREAK
  • if you do not see the Acorn Atom prompt, immediately switch off and re-check all work for errors

Enter the following program

10 PRINT $12
20 L=#8200
30 P=L
40[
50 INC #8000
60 JMP L
70]
80 LINK L

If all is well you should see two things:

  • the top left hand character should be changing (too fast to see)
  • there should be no screen noise

Leave this running for at least 10 minutes to make sure the system is stable

If you repeat the test with LK3 (NKEN) removed you should see large amounts of screen noise.

Notes

If you are using this board in conjunction with the Atom Video to HDMI Adaptor, then for best results use a cable with pin 4 disconnected at the Atom end. This dramatically reduces crosstalk. See this Stardot post for more information.

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