Z80 SBC Bug List

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Changes to Z80 SBC Board

  • Use spare GAL output as /IDERD16 [/RD * /IORQ * (/IDECS0 + /ICDCS1)]
  • SPSYNC needs a 10K pullup
  • Fix ground on JP1, pin 26 on schematic (layout is correct)
  • Consider mounting holes (not really much room)

Known problems in revision 1 board

  • /RD and /WR pins reversed on IDE connector (JP1)
  • Replace /RD to U3/16 & U3/17 with /IDE16RD (U5/14)
  • U1/30 (CS2) is grounded, and should be tied to Vcc
  • U1/1 should be grounded for use with 512K x 8 RAMs
  • /IORQ on PIO not connectd to net (schematic symbol has two pin 38's)
  • JP2 power and ground reversed
  • Foot print wrong for DS1233 (correct to use DS1813)
  • Holes for JP1 header too small (use 62/42 instead of 62/28)
  • Holes for S1 too small (use 62/42 instead of 60/35)
  • Holes for D2 too small (use 62/42 instead of 62/32)
  • Holes for U10 too large (use 80/42 instead of 80/52)
  • Holes for mounting tabs on J1, J2 too small (use 150/125 instead of 150/110)
  • Still two traces with 90 degree angle
  • Add /RD modification from above
  • Add SPSYNC 10K modification from above
  • C8/C22 too close together
  • Fix routing for U3, pin 26
  • Renumber JP1, JP2 to J?
  • Routing on D6 & /PIOCS can be cleaned up
  • DB-9 mounting tabs should be connected to GND net
  • Optionally increase Vcc and GND traces to 20 mils
  • Connect U6/9 to U6/20 for longer timer interrupt periods

Modification list

  • Jumper U7/36 to U3/36 (connects /IORQ)
  • Jumper U11/9 to U7/18 (connects CTSA)
  • Jumper U11/10 to U7/16 (connects DTRA)
  • Jumper U11/11 to U7/15 (connects TxDA)
  • Jumper U11/12 to U7/12 (connects RxDA)
  • Jumper U12/9 to U7/23 (connects CTSB)
  • Jumper U12/10 to U7/25 (connects DTRB)
  • Jumper U12/11 to U7/26 (connects TxDB)
  • Jumper U12/12 to U7/29 (connects RxDB)
  • Cut both GND traces to U1/30. Jumper U1/30 to U1/32 (Fixes CS2)
  • Cut JP2/1 to S1/2 (GND). Cut JP2/1 to D2/A (VRAW). Jumper JP2/1 to D2/A. Jumper JP2/2 to S1/2
  • Install U8 according to first board
  • Cut trace from JP1/23 to U3/35. Jumper JP1/23 to via under U3, near pins 37 & 38 (fixes /WR)
  • Cut trace from JP1/25 where trace runs between pins U3/37 & U3/38. Jumper JP1/25 to U3/35 (fixes /RD)
  • Cut trace from U3/16 between U7 and U3. Jumper U5/14 to U3/16 (deletes /RD, adds/IDERD16)
  • Jumper U6/9 to U6/20 (cascades CTC channel 2 to channel 3)