Address lines, and assorted links
by Mike Gordon
Connecting the remaining links
The address lines point to a memory location inside the cartridge ROM (or RAM). 16 bits are available for addressing (giving a total of 65536 memory locations, or 64 kilobytes), so we need 16 address lines. The address lines are driven by the 4040 counter chips.We also need to connect a few more links for other cartridge signals, such as Read (_RD), and Write (_WR).
Wire links
Solder in the following wire links:
5Y - 6J
7W - 7K
8T - 8U
8M - 15M
15V - 15Z
16U - 16W
16X - 16N
16J - 16L
17K - 17O
18W - 18Y
28G - 28H
30K - 31O
31J - 31L
32K - 32Y
38L - 38M
40I - 39Q
38P - 38F
18M - 18AM
34AM - 34Y
13M - 13E
29E - 29J
7I - 20D
28D - 28K
31M - 31AE
32AE - 24AF
23J - 33P
Cut tracks
Cut tracks at the following holes:
13P
14V
14M
15X
16K
17J
15L
18O
17W
19Y
16Z
23AA
23AB
23AC
24AD
24AE
23AF
29K
31P
30L
30O
29M
29N
29AE
Wire links on track side of board
In order to reduce "clutter" on the board, we can make some of our links on the track side of the Veroboard. This is somewhat more tricky than the usual method, and involves soldering directly to socket or component pins.
Cut the wire to the exact length required and strip only a couple of millimetres or so of insulation from the ends. Mount the wire firmly in place using Blu-Tack, making absolutely sure that the exposed ends are not bridging adjacent pins, then solder them.
Here is an example of such a link:
and here are the links you have to make.
34M - 37O
12K - 27M
12L - 27L
27W - 9Y
27V - 12AA
27U - 12X
27T - 12V
Progress so far...
Here's what the SMSReader should look like now:
This document (c) Mike Gordon 2000, 2001. Last updated 10th June, 2001.