2650 Max v1

Introduction

Welcome to my build of Michael Cvetanovski 's 2650 Max SBC.

More information here:

https://sites.google.com/site/gogleoops/2650-max

Micheal has some other interesting projects on his OLD Micros site as well, check it out:

https://sites.google.com/site/gogleoops/

This build was inspired by my very first computer an Electronics Australia 2650 system.

https://archive.org/stream/EA1978/EA%201978-05%20May#page/n57/mode/2up

I don't have that system anymore but still have the CPU, PROM and transformer. The CPU will be using in this build - nearly 40 years old now.

Read all about an awesome remake of this system I just stumbled upon:

http://www.postincrement.net/2650-remake-finished-and-working/

Features

  • 1Mhz 2650 CPU.
  • NVRAM chip used for RAM and ROM storage. The ROM area is “write protected” by the GAL logic.
  • PIPBUG monitor available.
  • MWBASIC monitor available.
  • TTL level 300 baud direct interface to pipbug monitor and mwbasic.
  • Three 8 bit input/output ports.
  • TTL level serial port.

Pictures

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_b1ackmai1er_images_2650_2650-1.jpg

Parts List

ItemQtyDescription
2650, 8255 socket,240pin DIP socket
DS1245A socket132pin DIP socket
PAL socket124pin narrow DIP socket
MC68B50 socket124pin DIP socket
IC11Signetics 2650 microcomputer
IC21i8255 PPI (programmable peripheral interface)
IC31Maxim DS1245Y-70 128Kb non-volatile memory
IC41GAL22V10 (preprogrammed)
IC51MC68B50 ACIA
IC61SN74LS14N hex inverter with schmitt trigger
Y211Mhz DIP14 5V active crystal oscillator
Y311.8432Mhz DIP14 5V active crystal oscillator
R1, R2, R4, R6, R7, R864K7 resistor
R5147R resistor
R91Current limit resistor 1K8, 2K2 etc
C1147uF tantalum capacitor
C2, C3, C4, C5, C6, C7, C9, C1080.1uF ceramic capacitors 2.54mm
D113mm LED
Reset1PCB mount push button
PortA, PortB, PortC, invgates42x5pin male pin header 2.54mm
Comms, A15, A16, E43 pin male header 2.54mm
H1, Ucomms24 pin male header 2.54mm

Assembly Instructions

If you have a complete set of parts, here's a suggested assembly guide

  1. All IC sockets
  2. Resistor R5
  3. Resistor R9
  4. All other resistors.
  5. 3mm LED - polarity important
  6. Reset SW1
  7. All 0.1uF capacitors
  8. Capacitor C1 - polarity important
  9. Crystal Y2, Y3
  10. Bend up pin 2 of SN74LS14N up solder in.
  11. All 2x5pin headers
  12. All 3pin and 4pin headers
  13. Power / reset connector
  14. Populate all IC sockets.

I found using a dab of superglue on the pin headers helped keep them in place for soldering. I also recommend using gold plated pin headers as the un-plated ones solder poorly and leave a unsatisfactory finish.

If you are using the v1 PCB as I am there are four modifications to be made which are documented on the designers site, see link above.

Resources

Assembly Instructions

If you have a complete set of parts, here's a suggested assembly guide

  1. All IC sockets
  2. Resistor R5
  3. Resistor R9
  4. All other resistors.
  5. 3mm LED - polarity important
  6. Reset SW1
  7. All 0.1uF capacitors
  8. Capacitor C1 - polarity important
  9. Crystal Y2, Y3
  10. Bend up pin 2 of SN74LS14N up solder in.
  11. All 2x5pin headers
  12. All 3pin and 4pin headers
  13. Power / reset connector
  14. Populate all IC sockets.

I found using a dab of superglue on the pin headers helped keep them in place for soldering. I also recommend using gold plated pin headers as the un-plated ones solder poorly and leave a unsatisfactory finish.

If you are using the v1 PCB as I am there are four modifications to be made which are documented on the designers site, see link above.

Resources

Memory Map - 4 x 32Kb blocks

0X00000-0X20000 A15 A16
0X00000 0X07FFF L L
0X08000 0X0FFFF H L
0X10000 0X17FFF L H
0X18000 0X20000 H H


builderpages/b1ackmai1er/2650.txt · Last modified: 2018/05/31 08:17 by b1ackmai1er
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