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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #125 on: July 22, 2016, 07:11:32 PM »
Sorry I will post it soon....
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #126 on: June 26, 2017, 12:50:58 AM »
Latest improvements:

I well probably do the rom reader with a pic microcontroller and counters with 8bit shift register:
https://drive.google.com/file/d/0B5vW-k7HbsL4UFJNNThVSDhnRDQ/view?usp=drivesdk
I used an MC14040 to generate the all the address bus except the last bit, so MC14040 generate A0-A11,  address A12 however is generated by two 74LS30 octal input nand gates connected to all the address,the put of the second nand gate is connected to RB7 of PIC16F77  which controls
To tri-state buffers that connect to the address bus via the green wires, the shifr register and the data bus 8bits are shifted to pin RB3 and is controlled by RB0-RB2.
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #127 on: June 26, 2017, 01:00:44 AM »
For the CPU it self, I started to get the hang off it...
I also noticed that it is a Z80 microprocessor with an Intel 8085 interface, that means I could easily adapt existing 8085 designs to work with the NSC800 or Z80 designs by adding a transparent latch  to AD0-7 and connecting the output by ALE signal...
 

Offline danadak

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Re: help! how to make a nsc800 computer?
« Reply #128 on: June 26, 2017, 07:20:40 AM »
Some ref material -


http://www.cryptomuseum.com/spy/fs5000/files/NSC800.pdf

https://archive.org/details/bitsavers_nationaldacroprocessorFamilyHandbook_8034824

http://www.hparchive.com/Journals/HPJ-1985-07.pdf


There is a cookbook, NSC800 Microprocessor Cookbook, cannot seem to find a free download link anywhere.


Regards, Dana.
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #129 on: June 26, 2017, 01:10:36 PM »
Thanks dana for the great reference material :-+
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #130 on: June 27, 2017, 08:54:46 AM »
this is the diagram:
https://drive.google.com/open?id=0B5vW-k7HbsL4MEdfRG1fWWlBSDg
sorry for the crudity of the drawing I didn't find some chips in eagle cad so I had to do it by hand and it didn't help that I rushed in drawing it too...  :-[
« Last Edit: June 28, 2017, 03:41:31 AM by ali6x944 »
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #131 on: June 28, 2017, 03:47:28 AM »
code in the pic so far:
config.h
Code: [Select]
#include <xc.h>
// include processor files - each processor file is guarded. 
// PIC16F77 Configuration Bit Settings

// 'C' source line config statements

// CONFIG
#pragma config FOSC = LP        // Oscillator Selection bits (LP oscillator)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config CP = OFF         // FLASH Program Memory Code Protection bit (Code protection off)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#define _XTAL_FREQ 32786


/*THE FIRST BIT OUT IS D7 & THE LAST BIT OUT IS D0, LIFO*/
char OUTPUT_SHIFT_REGISTER(){
    int i; //Set bit position in OUTPUT_ARRAY and counts the bit number
    char OUTPUT_ARRAY[8]; //Stores the byte OUTPUT OF THE SHIFT_REGISTER
    for(int i=0; i<=8;i++){
       
        PORTBbits.RB0=1; //Set the SHIFT/LOAD of 74ls166 to shift _high
        char Qh=PORTBbits.RB3; // Set char Qh to the value of RB3
        OUTPUT_ARRAY[i]=Qh; //Writes Qh value to the array OUTPUT_ARRAY in position i
        /*Clock for shifting the bits*/
        PORTBbits.RB2=1; //Set the CLOCK of 74ls166 to _high
        __delay_us(100);
        PORTBbits.RB2=0; //Set the CLOCK of 74ls166 to _low
    }
    return OUTPUT_ARRAY;

}

main.c
Code: [Select]
#include "config.h"
#include <stdio.h>
#include <xc.h>



void main(void) {
    TRISBbits.TRISB0=0; //RB0 set to output [ctrl SHIFT/LOAD of 74ls166]
    TRISBbits.TRISB1=0; //RB1 set to output [ctrl CLEAR of 74ls166]
    TRISBbits.TRISB2=0; //RB2 set to output [ctrl CLOCK of 74ls166]
    TRISBbits.TRISB3=1; //RB3 set to input  [read QH of 74ls166]
    TRISBbits.TRISB4=0; //RB4 set to output [ctrl CLOCK of MC14040]
    TRISBbits.TRISB5=0; //RB5 set to output [ctrl RESET of MC14040]
    TRISBbits.TRISB6=0; //RB6 set to output [ctrl tri-state buffer stage 74ls541]
    TRISBbits.TRISB7=1; //RB7 set to input  [read Y of 74ls30]
    TRISDbits.TRISD7=0; //RD7 set to output [ctrl A12 of tri-state buffer stage 74ls541]
    int a; //Set OUTPUT bit position of OUTPUT_SHIFT_REGISTER, LIFO -LAST IN FIRST OUT- ,MSB=0
    while(1){
        PORTBbits.RB6=1; //Set the tri-state Buffer of 74ls541 to _tri-state
        PORTBbits.RB1=0; //Set the CLEAR of 74ls166 to _low 
        __delay_us(100);
        PORTBbits.RB1=1; //Set the CLEAR of 74ls166 to _high
        PORTBbits.RB5=1; //Set the Reset to _high
        __delay_us(100);
        PORTBbits.RB5=0; //Set the Reset to _low
        int Clock; //clock count of MC14040
        for(int Clock=0; Clock<=8191; Clock++){
            if(PORTBbits.RB7!=1){
            PORTBbits.RB4=1; //Set the CLOCK of MC14040 _high
            __delay_us(100);
            PORTBbits.RB4=0; //Set the CLOCK of MC14040 _low
            PORTBbits.RB6=0; //Set the tri-state buffer stage 74ls541 to _enable
            PORTBbits.RB0=0; //Set the SHIFT/LOAD of 74ls166 to load _low
            OUTPUT_SHIFT_REGISTER();
            }
            else{
            PORTBbits.RB4=1; //Set the CLOCK of MC14040 _high
            __delay_us(100);
            PORTBbits.RB4=0; //Set the CLOCK of MC14040 _low
            PORTBbits.RB6=0; //Set the tri-state buffer stage 74ls541 to _enable
            PORTBbits.RB0=0; //Set the SHIFT/LOAD of 74ls166 to load _low
            PORTDbits.RD7=1; //Set A12 of tri-state buffer stage 74ls541 _high
            OUTPUT_SHIFT_REGISTER();
            }
        } 
       
    }
        return;
}
I'm using a pic16f77 with XC8 compiler.
« Last Edit: June 28, 2017, 03:49:32 AM by ali6x944 »
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #132 on: June 28, 2017, 04:00:53 AM »
I would like to use UART to get the memory data to my computer using a cp2102 USB bridge, so the controller is only sending data through UART...
but I'm really not that great yet in programming in XC8, but I'll try my best to make it work.
if u know any other way I can use to get the data of the micro, I would be happy to hear it :-+
 

Offline Bruce Abbott

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Re: help! how to make a nsc800 computer?
« Reply #133 on: June 28, 2017, 04:59:13 AM »
I would like to use UART to get the memory data to my computer using a cp2102 USB bridge, so the controller is only sending data through UART...
USB to serial is a good way to do it, but...

What do you intend to do with the 'data' once you get it into the computer? If you want to download code and run it on the NSC800 then you will need some RAM and a way to load the 'data' into it.

 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #134 on: June 28, 2017, 06:20:46 AM »
I would like to use UART to get the memory data to my computer using a cp2102 USB bridge, so the controller is only sending data through UART...
USB to serial is a good way to do it, but...

What do you intend to do with the 'data' once you get it into the computer? If you want to download code and run it on the NSC800 then you will need some RAM and a way to load the 'data' into it.


mmmm....
well I have a couple of  MB8464A static 8K byte ram, and TMS4416 DRAM...
I will certainly use the MB8464A SRAM, but for the  "way to load the 'data' into it." to the NSC800 computer I will use SCN2661BC1N28 EPCI to load the program to ram from my computer through a USB bridge similar Grant Searle  Z80 design.
What I intend to do with the 'data' once I get it into the computer is to see what the roms contain, these roms where salvaged with the processor from a scrap electronics from the same unit, also I'm ordering a minipro programmer and a uv eraser to erase the roms and reprogram them again... 
 

Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #135 on: June 28, 2017, 06:52:33 AM »
if u know cheaper more reliable programmers or erasers post them please... ur post will help me alot :-+
 

Offline C

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Re: help! how to make a nsc800 computer?
« Reply #136 on: June 28, 2017, 12:24:57 PM »
if you have to buy a UV Eraser, it would be much cheaper to use any of the many other choices that function like a rom that do not require a UV Eraser.

The information from old UV based roms can easily be transfered to a newer device.

Today unless you are trying make a very old clone, I would let the TMS4416's collect dust.
The MB8464A is not much better.

From digikey
64kx8 static ram. $2.65
128Kx8                  $3.16
512Kx8                 $5.48

ROM like
512kx8 flash based $1.70
64kx8 EEPROM      $3.12

So if you wire up just two 32 pin dip sockets, you should have all the ROM & RAM you need to start with and the extra space could be used in future.

So can you buy a UV eraser for less than $3.12?
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #137 on: June 28, 2017, 02:19:02 PM »
if you have to buy a UV Eraser, it would be much cheaper to use any of the many other choices that function like a rom that do not require a UV Eraser.

The information from old UV based roms can easily be transfered to a newer device.

Today unless you are trying make a very old clone, I would let the TMS4416's collect dust.
The MB8464A is not much better.

From digikey
64kx8 static ram. $2.65
128Kx8                  $3.16
512Kx8                 $5.48

ROM like
512kx8 flash based $1.70
64kx8 EEPROM      $3.12

So if you wire up just two 32 pin dip sockets, you should have all the ROM & RAM you need to start with and the extra space could be used in future.

So can you buy a UV eraser for less than $3.12?

I guess u are right, I went to digikey and I saw:
SST39SF010A-70-4C-PHE         FLASH 1MBIT 70NS   1.44000$
AS6C62256-55PCN                    SRAM 256KBIT 55NS  2.53000$

this is great value for money, my only concern is the extremely low address propagation delay and its effects on the processor ability to take to it...
for the AM2764 UV ROMs I have, the propagation delay is 250ns [email protected] +-5%
for the SST39SF010A-70-4C-PHE ROM, the propagation delay is 70ns [email protected]
the same thing holds true for the SRAM also...
will this reduction in propagation delay have any effect on a multiplexed bus processor, if so is it bad or good, if its bad how can I fix it?
 

Offline Bruce Abbott

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Re: help! how to make a nsc800 computer?
« Reply #138 on: June 28, 2017, 04:15:08 PM »
if u know cheaper more reliable programmers or erasers post them please... ur post will help me alot :-+
The Minipro is one of the cheapest and is pretty reliable. Watch out though because they have apparently been 'cloned' and the fakes may not work as good. 

I got a cheap nasty eraser from eBay which actually works fine. However for the same price you could buy several EEPROMs, which program faster and erase in a few seconds. 'Vintage' W27C512 EEPROMs sell on eBay for ~$1 each including postage. Unlike more modern EEPROMs these come in a 28 pin DIP package which is easier to work with.

I used a 28F101 in PLCC for the prototype of my current Z80 project. The PLCC socket was a pain to wire up and the chip is not easy to remove, and every now and then I have to sandpaper the pins to get good contact. I changed to the W27C512 for the production version of my project.   
 
Quote
I will certainly use the MB8464A SRAM
Yes that should be fine. You could map the ROM to the lower 48k and the RAM to the upper 8k, or allocate 32k to each and then you would be able to upgrade to 32k RAM later on.

Quote
for the  "way to load the 'data' into it." to the NSC800 computer I will use SCN2661BC1N28 EPCI to load the program to ram from my computer through a USB bridge similar Grant Searle  Z80 design.
In that case you just need to modify Grant Searle's code to work with the SCN2661. This may take a bit of trial and error to get working, so using an EEPROM would be a good idea (having to wait 20 minutes to erase your UV EPROM makes for a very slow development cycle!).

Quote
will this reduction in propagation delay have any effect on a multiplexed bus processor, if so is it bad or good, if its bad how can I fix it?
Short propagation delays can be a problem if the memory responds too quickly and violates setup and hold times. However I don't think that will be a problem with the NSC800 as the bus timing doesn't appear to rely on long propagation delays. Another potential problem is noise on the bus caused by fast transitions. Make sure you have good low resistance ground wiring and power supply bypass capacitors on every chip.
   
 
« Last Edit: June 28, 2017, 04:17:21 PM by Bruce Abbott »
 
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Offline C

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Re: help! how to make a nsc800 computer?
« Reply #139 on: June 28, 2017, 05:48:43 PM »
One big difference between the
W27C512 EEPROM & newer generation chips is how easy the chips are to erase and program.

For  W27C512 you really need a programmer.

For SST39SF010A-70-4C-PHE a micro controller or a running NSC800/Z80 can program the chip. The only hard part is the need to enable chip for writes which is not that hard to do. You can not run a program in the chip you are programming, but it's not that hard to put programming code in ram if your using the NSC800/Z80 to program chip.

Once you have a microcomputer running, you may not even need a rom.
Look at

Here an Atmega32A loads a program in the Z80's ram starting at address 0H and then releases the Z80 reset.

So if you want to be cheap, no programmer like Minipro is needed.
 
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #140 on: June 28, 2017, 07:19:54 PM »
Interesting....
I have never thought of using a micro as a ram program loader...
It's certainly a cool trick to use :-+
 

Offline C

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Re: help! how to make a nsc800 computer?
« Reply #141 on: June 29, 2017, 02:42:59 AM »

In general terms a shorter propagation delay is a good thing.
What matters is how the memory is connected.
Back in the 80's I used/worked on a system that had the equal of the Z80/NSC800 wait states. Some memory functioned with 0 wait states. Some functioned with 1,2,? wait states. It was all the same speed memory. The difference was the connection path. Some memory had 6 buffer/transceiver chips in signal path while others had fewer to none.
It had a system bus that was shared with other CPU's and when busy with different CPU, this CPU had to wait.   

To see what works you need to check each signal. When does it become valid? When does it go in-valid. Can the logic output a glitch (a signal that looks valid at receiver but is not).
When a signal goes to a chip, how is effected in time. 

In general as you speed up the clock of a microprocessor you need faster memory. When memory is too slow you have to add wait states to tell the CPU more time is needed. Or you have to slow down the CPU clock which also gives more time. If memory is faster then most memory can wait for slow CPU.

It is possible that that you can have a faster system with a slower CPU clock. Wait states are steps in time. 1 ns too slow and you have to add a wait state that costs time.

The critical part is that data is there and stable at CPU pins when the CPU reads it. That data is stable at memory chips pins when memory needs it. The same is true for other chips.
It is good to have extra time as many things can change when the signal actually changes at the pin of a chip.

The Z80 puts some data on it's address bus. At some time it outputs a signal that says address data should be good. With out this logic signal the logic, memory & IO would not know that address data is unchanging.
As the Z80 has a separate data bus the same thing happens on a write, the WR signal states write data is stable and signals " grab it " when WR goes inactive.
Note that these two (address & data ) are separate and one could be valid before or after the other. Some very old memory required external logic to insure that address happened before data.
For NSC800 you have a multiplexed address bus and data bus. For a read from memory or io this is not a big problem. The memory or IO needs some time before data can be valid on it's pins. For a memory or io write, this sharing reduces the time write data can be on the bus.   

To get from multiplexed address/data bus to separate complete address bus, you use ALE signal & a latch. 
Is address data stable at the input of latch for a long enough time before it's latched with ALE signal?
When is address on the output of latch stable?
When does low address get to memory chip?
When does high address get to memory chip?
Need to do same for each and every pin on all.

In old designs, you might see some inverters or gates connected in series. Two inverters in series = time delay.
A faster or slower inverter part could break the system.

You need to check the time each signal takes to see if it's in the allowed range.

A fun fact, The CRAY 1 to get the speed actually put the address data and address valid signal on the output at same time. The Address valid signal's wire  length was adjusted to meet needs at destination
.
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #142 on: June 29, 2017, 06:57:17 AM »
quick question:
can wires have some sort of propagation delay? 
I know for certain that long power lines have horrible inductive behavior, that might case power up problems, and increasing the on-chip noise....
 
 

Offline Bruce Abbott

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Re: help! how to make a nsc800 computer?
« Reply #143 on: June 29, 2017, 06:58:15 AM »
For  W27C512 you really need a programmer.
True, but a programmer is a good tool to have around anyway. The Minipro can also program GALs and MCUs that need high voltage, and test RAM and logic chips.

Quote
For SST39SF010A-70-4C-PHE a micro controller or a running NSC800/Z80 can program the chip. The only hard part is the need to enable chip for writes which is not that hard to do. You can not run a program in the chip you are programming, but it's not that hard to put programming code in ram if your using the NSC800/Z80 to program chip.
But you need to write the code and get it into the RAM somehow, which means either burning it into an EPROM for the CPU to boot from (chicken and egg problem) or loading it via DMA with some other device.

Quote
Look at

Here an Atmega32A loads a program in the Z80's ram starting at address 0H and then releases the Z80 reset.
It's a clever idea, but quite a bit more complicated than just programming an EPROM and plugging it in. The more complex the design the more things can go wrong with the build, and the harder it is to debug. Since ali6x944 struggled just to read an EPROM with an MCU, I suggest going with the simplest solution - at least to start with.
 
   
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #144 on: June 29, 2017, 07:05:30 AM »
For  W27C512 you really need a programmer.
True, but a programmer is a good tool to have around anyway. The Minipro can also program GALs and MCUs that need high voltage, and test RAM and logic chips.

Quote
For SST39SF010A-70-4C-PHE a micro controller or a running NSC800/Z80 can program the chip. The only hard part is the need to enable chip for writes which is not that hard to do. You can not run a program in the chip you are programming, but it's not that hard to put programming code in ram if your using the NSC800/Z80 to program chip.
But you need to write the code and get it into the RAM somehow, which means either burning it into an EPROM for the CPU to boot from (chicken and egg problem) or loading it via DMA with some other device.

Quote
Look at

Here an Atmega32A loads a program in the Z80's ram starting at address 0H and then releases the Z80 reset.
It's a clever idea, but quite a bit more complicated than just programming an EPROM and plugging it in. The more complex the design the more things can go wrong with the build, and the harder it is to debug. Since ali6x944 struggled just to read an EPROM with an MCU, I suggest going with the simplest solution - at least to start with.
 
   

I agree, maybe in the future I can do this but for now I should stick to the basics as Bruce Abbott said. :-+
 

Offline Bruce Abbott

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Re: help! how to make a nsc800 computer?
« Reply #145 on: June 29, 2017, 07:10:00 AM »
quick question:
can wires have some sort of propagation delay? 
I know for certain that long power lines have horrible inductive behavior, that might case power up problems, and increasing the on-chip noise....
Yes, wires do have propagation delay. However in the typical lengths required it is very small compared to the chips you are using. Inductance and capacitance can become a problem if they cause ringing or 'ground bounce'. High speed designs often have small resistors in series to damp oscillations, and 'meander' wires to fine tune the delays.     
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #146 on: June 29, 2017, 07:13:14 AM »
if u know cheaper more reliable programmers or erasers post them please... ur post will help me alot :-+
The Minipro is one of the cheapest and is pretty reliable. Watch out though because they have apparently been 'cloned' and the fakes may not work as good. 

I got a cheap nasty eraser from eBay which actually works fine. However for the same price you could buy several EEPROMs, which program faster and erase in a few seconds. 'Vintage' W27C512 EEPROMs sell on eBay for ~$1 each including postage. Unlike more modern EEPROMs these come in a 28 pin DIP package which is easier to work with.

I used a 28F101 in PLCC for the prototype of my current Z80 project. The PLCC socket was a pain to wire up and the chip is not easy to remove, and every now and then I have to sandpaper the pins to get good contact. I changed to the W27C512 for the production version of my project.   
 
Quote
I will certainly use the MB8464A SRAM
Yes that should be fine. You could map the ROM to the lower 48k and the RAM to the upper 8k, or allocate 32k to each and then you would be able to upgrade to 32k RAM later on.

Quote
for the  "way to load the 'data' into it." to the NSC800 computer I will use SCN2661BC1N28 EPCI to load the program to ram from my computer through a USB bridge similar Grant Searle  Z80 design.
In that case you just need to modify Grant Searle's code to work with the SCN2661. This may take a bit of trial and error to get working, so using an EEPROM would be a good idea (having to wait 20 minutes to erase your UV EPROM makes for a very slow development cycle!).

Quote
will this reduction in propagation delay have any effect on a multiplexed bus processor, if so is it bad or good, if its bad how can I fix it?
Short propagation delays can be a problem if the memory responds too quickly and violates setup and hold times. However I don't think that will be a problem with the NSC800 as the bus timing doesn't appear to rely on long propagation delays. Another potential problem is noise on the bus caused by fast transitions. Make sure you have good low resistance ground wiring and power supply bypass capacitors on every chip.
   
 
can u give me the seller name of TL866, I don't really trust the current one I have:
http://www.ebay.com/itm/191796916274
 

Offline C

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Re: help! how to make a nsc800 computer?
« Reply #147 on: June 29, 2017, 09:45:51 AM »

If you have a TL866 now then test it!

If the chip you use to test it with came from some place like digikey then chance of bad chip is small.
 
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Offline ali6x944

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Re: help! how to make a nsc800 computer?
« Reply #148 on: June 29, 2017, 10:35:13 AM »

If you have a TL866 now then test it!

If the chip you use to test it with came from some place like digikey then chance of bad chip is small.
No, u misunderstood me...
What I meant was I will be ordering one and I don't trust the seller I have posted the link for...
 

Offline Bruce Abbott

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Re: help! how to make a nsc800 computer?
« Reply #149 on: June 29, 2017, 02:22:46 PM »
can u give me the seller name of TL866, I don't really trust the current one I have:
http://www.ebay.com/itm/191796916274
The official eBay store listed on Autoelectric's dealer page is Electronic DIY.

TL866CS with 4 adapters is US$47.
 
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