1.1 --- a/CPU_ROM_KBD.sch Tue Feb 01 00:18:08 2022 +0100
1.2 +++ b/CPU_ROM_KBD.sch Sat Feb 12 16:42:18 2022 +0100
1.3 @@ -556,7 +556,7 @@
1.4 5900 3800 6600 3800
1.5 Wire Wire Line
1.6 5900 3900 6600 3900
1.7 -Text GLabel 8800 3750 2 50 Input ~ 0
1.8 +Text GLabel 8650 3300 2 50 Input ~ 0
1.9 ~NMI
1.10 Text GLabel 6200 4200 2 50 Input ~ 0
1.11 ~IRQ
1.12 @@ -582,7 +582,7 @@
1.13 Text GLabel 7500 900 2 50 Output ~ 0
1.14 CAPS_LOCK
1.15 Text Notes 6800 3200 0 50 ~ 0
1.16 -Issue 6 boards tend to have\nIC18 (74LS08) fitted for some\nkind of buffering for ~NMI\nand for PHI_OUT.\n\nLK8 is made to enable buffering via IC18 for ~NMI.\nLK9 is made to disable buffering via IC18 for PHI_OUT.\n\nOn such boards, without any links made, buffering\nonly seems to be done for PHI_OUT.\n
1.17 +Issue 6 boards tend to have\nIC18 (74LS08) fitted for some\nkind of buffering for ~NMI\nand for PHI_OUT.\n\nLK8 is made to disable buffering via IC18 for ~NMI.\nLK9 is made to disable buffering via IC18 for PHI_OUT.\n\nThese buffers were introduced for the Aberdeen ULA,\nand are superfluous for the Ferranti ULA.\nSee the "Acorn Information - Volume 1" document.\n
1.18 $Comp
1.19 L 74xx:74LS08 IC18
1.20 U 4 1 61F0E37D
1.21 @@ -641,7 +641,7 @@
1.22 Text GLabel 8100 3600 2 50 Input ~ 0
1.23 5V
1.24 Wire Wire Line
1.25 - 8500 4000 7600 4000
1.26 + 7800 4000 7600 4000
1.27 Wire Wire Line
1.28 7600 4500 7600 4200
1.29 Wire Wire Line
1.30 @@ -676,7 +676,7 @@
1.31 Wire Wire Line
1.32 6800 3300 8500 3300
1.33 Wire Wire Line
1.34 - 8500 3300 8500 3500
1.35 + 8500 3300 8500 4000
1.36 Connection ~ 6800 4100
1.37 Wire Wire Line
1.38 6800 4100 6900 4100
1.39 @@ -740,18 +740,18 @@
1.40 Text Label 6600 6100 2 50 ~ 0
1.41 D[0..7]
1.42 $Comp
1.43 -L Jumper:Jumper_3_Bridged12 LK8
1.44 +L Jumper:Jumper_2_Open LK8
1.45 U 1 1 622A19C1
1.46 -P 8500 3750
1.47 -F 0 "LK8" V 8546 3837 50 0000 L CNN
1.48 -F 1 "Enable buffer" V 8455 3837 50 0000 L CNN
1.49 -F 2 "" H 8500 3750 50 0001 C CNN
1.50 -F 3 "~" H 8500 3750 50 0001 C CNN
1.51 - 1 8500 3750
1.52 - 0 -1 1 0
1.53 +P 8000 4000
1.54 +F 0 "LK8" H 8000 4250 50 0000 C CNN
1.55 +F 1 "Disable buffer" H 8000 4150 50 0000 C CNN
1.56 +F 2 "" H 8000 4000 50 0001 C CNN
1.57 +F 3 "~" H 8000 4000 50 0001 C CNN
1.58 + 1 8000 4000
1.59 + -1 0 0 -1
1.60 $EndComp
1.61 Wire Wire Line
1.62 - 8800 3750 8650 3750
1.63 + 8650 3300 8500 3300
1.64 $Comp
1.65 L power:PWR_FLAG #FLG0108
1.66 U 1 1 62024ADF
1.67 @@ -766,6 +766,11 @@
1.68 Connection ~ 4450 5000
1.69 Wire Wire Line
1.70 4450 5000 4550 5000
1.71 +Text Notes 4300 6450 0 50 ~ 0
1.72 +Note that KiCad cannot determine whether ~CS\nis driven via LK1, so a power flag is required.
1.73 +Connection ~ 8500 3300
1.74 +Wire Wire Line
1.75 + 8200 4000 8500 4000
1.76 Wire Bus Line
1.77 2200 1500 6800 1500
1.78 Wire Bus Line
1.79 @@ -780,6 +785,4 @@
1.80 2100 1600 2100 4200
1.81 Wire Bus Line
1.82 4400 1600 4400 4500
1.83 -Text Notes 4300 6450 0 50 ~ 0
1.84 -Note that KiCad cannot determine whether ~CS\nis driven via LK1, so a power flag is required.
1.85 $EndSCHEMATC