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--- builderpages:b1ackmai1er:2650 [2025/02/19 14:05] – Revision from 2025-02-19
+++ builderpages:b1ackmai1er:2650 [2026/06/15 12:57] (current) – external edit 127.0.0.1
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+/* Imported from Wayback Machine
+   Original URL : https://www.retrobrewcomputers.org/doku.php?id=builderpages:b1ackmai1er:2650
+   Snapshot date: 2025-10-05
+   Generator    : wayback-archiver
+*/
+====== 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 =====
+Mhz 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 =====
+{{[[lib:plugins:ckgedit:fckeditor:userfiles:image:builderpages:b1ackmai1er:images:2650:2650-1.jpg]]
+===== Parts List =====
+^Item                           ^Qty^Description                                  ^
+|2650, 8255 socket,             |2  |40pin DIP socket                             |
+|DS1245A socket                 |1  |32pin DIP socket                             |
+|PAL socket                     |1  |24pin narrow DIP socket                      |
+|MC68B50 socket                 |1  |24pin DIP socket                             |
+|IC1                            |1  |Signetics 2650 microcomputer                 |
+|IC2                            |1  |i8255 PPI (programmable peripheral interface)|
+|IC3                            |1  |Maxim DS1245Y-70 128Kb non-volatile memory   |
+|IC4                            |1  |GAL22V10 (preprogrammed)                     |
+|IC5                            |1  |MC68B50 ACIA                                 |
+|IC6                            |1  |SN74LS14N hex inverter with schmitt trigger  |
+|Y2                             |1  |1Mhz DIP14 5V active crystal oscillator      |
+|Y3                             |1  |1.8432Mhz DIP14 5V active crystal oscillator |
+|R1, R2, R4, R6, R7, R8         |6  |4K7 resistor                                 |
+|R5                             |1  |47R resistor                                 |
+|R9                             |1  |Current limit resistor 1K8, 2K2 etc          |
+|C1                             |1  |47uF tantalum capacitor                      |
+|C2, C3, C4, C5, C6, C7, C9, C10|8  |0.1uF ceramic capacitors 2.54mm              |
+|D1                             |1  |3mm LED                                      |
+|Reset                          |1  |PCB mount push button                        |
+|PortA, PortB, PortC, invgates  |4  |2x5pin male pin header 2.54mm                |
+|Comms, A15, A16, E             |4  |3 pin male header 2.54mm                     |
+|H1, Ucomms                     |2  |4 pin male header 2.54mm                     |
+===== Assembly Instructions =====
+If you have a complete set of parts, here's a suggested assembly guide
+All IC sockets
+Resistor R5
+Resistor R9
+All other resistors.
+mm LED - polarity important
+Reset SW1
+All 0.1uF capacitors
+Capacitor C1 - polarity important
+Crystal Y2, Y3
+Bend up pin 2 of SN74LS14N up solder in.
+All 2x5pin headers
+All 3pin and 4pin headers
+Power / reset connector
+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 =====
+Microcomputer
+https://en.wikipedia.org/wiki/Signetics_2650
+RS232 level logic circuits for the 68B50
+https://rc2014.co.uk/modules/serial-io/
+http://searle.hostei.com/grant/6809/Simple6809.html
+===== Assembly Instructions =====
+If you have a complete set of parts, here's a suggested assembly guide
+All IC sockets
+Resistor R5
+Resistor R9
+All other resistors.
+mm LED - polarity important
+Reset SW1
+All 0.1uF capacitors
+Capacitor C1 - polarity important
+Crystal Y2, Y3
+Bend up pin 2 of SN74LS14N up solder in.
+All 2x5pin headers
+All 3pin and 4pin headers
+Power / reset connector
+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 =====
+Microcomputer
+https://en.wikipedia.org/wiki/Signetics_2650
+RS232 level logic circuits for the 68B50
+https://rc2014.co.uk/modules/serial-io/
+http://searle.hostei.com/grant/6809/Simple6809.html
+===== 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  |
+\\