​Soldering perfboard

A project log for Earth Lander 84

Like the classic Lunar Lander video game but on Earth and with no graphics, only some 7-segment displays

matsengmatseng 02/03/2016 at 07:163 Comments

I took a perfboard and soldered up power and the data/address busses of the MCU, SRAM, NVRAM and the address bus latch.

I did't really care about the exact order of the bits when wiring them up, I just went for the easiest layout. I'm not really sure why the manufacturers even care about designating the D0..D7 on a SRAM, the order is irrelevant as long as you don't move the chip to another system with live data on it. Same thing with the address bus. On a (EE)PROM it's required to carefully keep track of the A's and D's of course.

This is how it ended up:

 Z8671                                  HEADER
--------                                ------
VCC  P36
X2   P31                                    RW
X1   P27                                    /E
TX   P26                                    a7
RX   P25      6264      DS135               a6
/RES P24     -------   --------             a5
R/W  P23     NC  VCC    A  VCC              a4
/DS  P22     A   /WE    A  /WE              a3
/AS  P21     A   CS2    A    A    LS373     a2
P35  P20     A     A    A    A   -------    a1
GND  P33     A    a6    A   a6   /OE VCC    a0
P32  P34     a4   a7    a4  a7   a7   a6    d7
A8    d7     a5  /OE    a5 /OE   d7   d6    d6
A9    d6     a3   a2    a3  a2   d5   d4    d5
A10   d5     a0 /CS1    a0 /CE   a5   a4    d4
A11   d4     a1   d7    a1  d7   a3   a2    d3
A12   d3     d5   d6    d5  d6   d3   d2    d2
A13   d2     d3   d4    d3  d4   d1   d0    d1
A14   d1     d1   d2    d1  d2   a1   a0    d0
A15   d0     GND  d0    GND d0   GND  LE   GND

Only the front side is shown, the backside is a horrible mess of "roadrunner"-style point-to-point wiring using insulated magnet wire that I just soldered thru the insulation with a 400C soldering iron.


Yann Guidon / YGDES wrote 02/04/2016 at 13:31 point

What about a 573 instead of a 373 ? Too modern ?

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matseng wrote 02/04/2016 at 14:35 point

Well - yes actually... The 573 do have a proper and easy to work with pinout compared to the 373. What were the designers thinking when they did the 373? Following the same type of layout as the standard and/or/nand gates wasn't maybe the best of ideas of a bus-oriented latch...

I do have some junkboxes with ancient stuff in them, but no 573 in sight there and I really want to be using parts as true the the period as possible. I'm already a bit miffed over the fact that the AY-3-89xx is far to new to fit in with the rest of the parts... ;-)

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Yann Guidon / YGDES wrote 02/04/2016 at 14:49 point

I suppose they were thinking "Oh DANG I don't have an extral metal layer to send this signal to the other side of the chip" :-/
Early ICs had only one metal layer, crossing wires was tedious and needed a pass in the (slow) diffusion layer...

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