CS/A65 PETCPU Jumper settings

This table describes the jumper settings available on the board

Jumper

Description

Setting

Meaning

VC1581 setting

PETCPU setting

JP1

1/2MHz system clock switch

1-2

2 MHz

8032 (experimental)

2-3

1MHz

4032

JP2

I/O size selector A8

1-2

A8=0

don't care

2-3

A8 don't care

JP3

I/O size selector A9

1-2

A9=0

2-3

A9 don't care

JP4

I/O size selector A10

1-2

A10=0

2-3

A10 don't care

JP5

ROM size selection. JP5,6, and 7 select the lowest address where ROM is selected (from 64k down). A15 is always high

1-2

A14 high

2-3

A14 low

JP6

1-2

A13 high

2-3

A13 low

JP7

1-2

A12 high

2-3

A12 low

JP8

External (bus) memory A17

1-2

+128k

2-3

+0k

JP9

External (bus) memory A16

1-2

+0k

2-3

+64k

JP14

I/O select enable

1-2

/IOSEL enabled

2-3

/IOSEL disabled

JP15

RAM size selection. JP15,16, and 17 select the highest address where RAM is selected (from 0k up). A15 is always low

1-2

A14 high

2-3

A14 low

JP16

1-2

A13 high

2-3

A13 low

JP17

1-2

A12 high

2-3

A12 low

JP18

External (bus) memory A15 invert

1-2

invert A15 on bus

2-3

do not invert A15

JP19

External (bus) memory A12 invert

1-2

invert A12 on bus

2-3

do not invert A12

JP20

8/32k RAM switch

1-2

8k RAM (6264)

2-3

32k RAM (62256)

JP21

Enable on-board RAM

1-2

disable on-board RAM (use bus memory only)

depends on whether you have on-board RAM

2-3

enable on-board RAM, use bus memory only above address set with JP15/16/17.

JP22

ROM address A18

1-2

depends on the ROM size and where the ROM content is in the ROM IC. For example I have a 64k ROM, and the PET ROM at $0000-$7fff, and the VC1581 ROM at $8000-$ffff. This results in these jumper settings:

	JP22	JP23	JP24	JP25
PET 4032	1-2	5-6	1-2	1-2
VC1581	1-2	5-6	1-2	5-6

3-4

Control port D3

5-6

JP23

ROM address A17

1-2

3-4

Control port D2

5-6

JP24

ROM address A16

1-2

3-4

Control port D1

5-6

JP25

ROM address A15

1-2

3-4

Control port D0

5-6