Rodney the Robot (1979) by David L Heiserman - circuit errors?

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mark556

Joined Sep 30, 2016
2
Recently deciding to complete my 1987 project (!!) from the 1979 book “How to Build Your Own Self programming Robot” (by David L Heiserman) that I started whilst at college I would like to confirm a few possible circuit errors that I’ve noted.

From Schematic 11.2(attached);
Memory Address lines MA0 - MA3 pass through the 74LS367 buffer/driver (IC Z121) on the lower 4 (of 6) gates,whilst MA4 & 5 pass through on the upper 2 gates.

MA6 & MA7 pass through on the bottom 74LS367 (IC Z122), but the input-output pins 11/12 & 13/14 appear crossed.

The same error also appears on schematic 11-3 for the High-order memory bits MA14 and MA15. Scrutinizing even further it looks like the data lines MD4-MD7 (on Z1191) are also crossed as these connect to the Data-In pins of the RAM chips*. The same error being seen back on schematic 11-2 with MD0-MD3 on Z122.


My conclusion being that both IC’s Z1191 & Z122 input / output pins should have been drawn mirrored?

The corresponding circuit description from the book has been attached, along with the two relevant circuits.

(* The memory chips listed for the extended memory actually have separate Data-in and Data-out pins (and are 1 bit chips!) therefore I intend to update these to some standard type (maybe nonvolatile, like FRAM’s), but before commencing would like to rectify any errors on the circuit ‘as drawn before making my updates)
 

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HW-nut

Joined May 12, 2016
94
It's been a long time since I looked at multiplexed address/ data busses. I used to work at a manufacture for SS50 bus systems/ 6809 processors. I'm not sure if I would have the patience for the build, a lot of work, not much performance.
 

Thread Starter

mark556

Joined Sep 30, 2016
2
Back in 87/88 I'd completed most of the build but just need to confirm the errors for the memory that was not built, I can see it is wrong but just looking for another pair of eyes to confirm the errors.
 
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