Z80 SBC Bug List

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)