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Anyone else building an Apple-1 ?

It'll possibly be an earth loop.

I won't suggest removing the safety earth from the oscilloscope though :)!

Dave
 
:)

The Apple-1 isn't actually earthed (as designed, I'm using the US 110V circuit) and is fed from a 240/110V 5kVA transformer and the earth is through the TV which is on the 240V feed, so its probably not surprising when I think about it.
 
Its now up and running its first program. A simple memory test program that seems to work fine. What's interesting after all I have read about the A1 being a very marginal design and is prone to crashing, it seems to work really well (well within its big and obvious limitations :) ) and hasn't crashed once.

The cassette port is working fine and the ground loop noise isn't a problem when you use a battery powered recorder/laptop.

First program1.jpg

Yes, I must tidy up the workshop.
 
What's interesting after all I have read about the A1 being a very marginal design and is prone to crashing, it seems to work really well (well within its big and obvious limitations :) ) and hasn't crashed once.
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Where did you read this? I have always found the A1 to be very stable.
 
BTW, on my boards I have fixed the issue with extra dots on the display by pulling down the output C-13, Pin 6 to ground, with a 2.2K resistor.

More info on this is here:

 
d5aa96 said:
Where did you read this? I have always found the A1 to be very stable.
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Applefritter and stories of Lisa Loop's experiences with them.

Mine certainly appears to be stable.

Thanks for the advice on the screen dots. Dont think my display is helped by the ground noise I am experiencing probably due to the mix of 240V monitor and 110V A1 and with the LCD I am overdriving the signal a bit too much to make it stable which is making the dots worse.

Need to check the earth bonding in my transformer as it is about 40 years old.
 
First of the big blues turned up today.

Big blue.jpg

Brand new, made to order. Daftly expensive. (£18 !) and mouser expect you to pay for delivery !
 
Eudimorphodon said:
That's the route taken by most not-trying-to-be-original Apple I clones, including the Briel Computers Replica-1 circa 2003-ish, which makes it maybe the first "modern" Apple I clone?

Honestly, considering the way the Apple-1 treats its video circuitry I'd consider it a reasonable route to take because, as you note, unwinding the original design to use SRAM instead of those shift registers results in a pretty silly mess. An Apple I with memory mapped video is pretty close to a Commodore PET, so you might as well just make a PET replica.

(Actually this has me thinking, are the schematics for the Sphere-1 out there in the wild? It was a 6800-based machine that predated the Apple-1 that had memory-mapped video, it might be an interesting replication target.)
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A late reply perhaps, but I also think building a Briel Replica 1 is a very reasonable way to go nowadays. I am very fond of mine. I have it working with USB to Serial input (the slowest way to input programs aside from typing them), a P-LAB Apple 1 micro-SD storage card (which has a very functional command line), and now Uncle Bernie's improved Gen 2 cassette interface. (I don't use a bus extender, only one card at a time).

If you actually want to use the thing, the Briel replica 1 plus is a fun functional build that can be done in a couple of hours for an experienced builder. The expansion slot is proving to be quite compatible (lacking -12v but there is an input pad by the slot, and the new ACI doesn't need -12v anyway).

I admire those who have the desire to stick to 100 percent original circuitry, but I am having plenty of fun with the Briel. Some of the builds here are absolutely beautiful though.
 
Gary C said:
Applefritter and stories of Lisa Loop's experiences with them.

Mine certainly appears to be stable.
Click to expand...
It can be very dependent on what you're running. With my Obtronix clone, I ported an updated figForth to use the CFFA1 and it would randomly run off into the weeds. Not until I added extra decoupling caps to the DRAM chips (underneath the PCB so as not to detract from the aesthetics) did it finally run stably.

skate323k137 said:
A late reply perhaps, but I also think building a Briel Replica 1 is a very reasonable way to go nowadays. I am very fond of mine. I have it working with USB to Serial input (the slowest way to input programs aside from typing them), a P-LAB Apple 1 micro-SD storage card (which has a very functional command line), and now Uncle Bernie's improved Gen 2 cassette interface. (I don't use a bus extender, only one card at a time).

If you actually want to use the thing, the Briel replica 1 plus is a fun functional build that can be done in a couple of hours for an experienced builder. The expansion slot is proving to be quite compatible (lacking -12v but there is an input pad by the slot, and the new ACI doesn't need -12v anyway).

I admire those who have the desire to stick to 100 percent original circuitry, but I am having plenty of fun with the Briel. Some of the builds here are absolutely beautiful though.
Click to expand...
One thing that *could* have been done with the Briel version was to improve the terminal section to actually do useful things like X,Y cursor addressing, screen clears, backspace, etc. IIRC, Vince actually implemented some extra terminal functionality in the Propeller code in his second generation design but was removed for production because it was incompatible with some of the test programs that wrote all 256 values to the terminal. The extra control codes messed with the display making it not 100% compatible with the Apple 1. Too bad.
 
Finally got my tape drive ACI card and EPROM cards installed

Can't quite work out why the memory was rearranged. It was obviously designed to be at 0000 to 0FFF for bank 0 and 1000 to 1FFF for bank 1 as the jumpers for them have little solder pads to bridge, but bank 1 was mapped to E000 for BASIC to sit in.

Were 4k EPROMs more expensive than RAM in 74/75 ? Would have seemed more obvious to have fitted a socket for one than waste 4K of RAM.

anyway, I have fitted a two slot riser card to the internal bus socket so that the ACI and a two socket EPROM card can be fitted. Mapped one of the sockets to E000 and put BASIC in it so you don't have to load it every time you turn the machine on.

I had to fit a jumper wire for the other socket as the manual has an error so I had connected the chip select to the wrong bus connection, but I can bridge that later on board with a bit of patch wire.

Its still a crap machine, but its my crap machine and its fun.
 

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Gary C said:
Its still a crap machine, but its my crap machine and its fun.
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Hey, I think it's great.

Nice work aligning the cards with standoffs, they are always handy to have around.

I would love to make a wooden enclosure for one of my franken-8-bit builds one of these days. It's far far down the project list though.
 
What is amazing, I never intended to do this when the motherboard was installed and its just a complete fluke that the standoff's are just about the right size.
 
Finally going to be tackling this build.

If anyone has spares of the parts not contained in the "Uncle Bernie" kit, let me know, I may be interested in buying them or trading something fun for them.
 
All I have is one solitary blue Sprauge cap.

I do have my order list from Mouser

Mouser No:Mfr. No:Desc.:Customer NoOrder Qty.
553-F-31XF-31XPower Transformers Power Transformers POWER XFMR 10.0Vct@3.0A 115V CHASSIS MOUNT w/LEADS1
553-F40XF-40XPower Transformers Power Transformers POWER XFMR 26.8Vct@1.0A 115V CHASSIS MOUNT w/LEADS1
75-39D538G015JP639D538G015JP6Aluminium Electrolytic Capacitors - Axial Leaded Aluminium Electrolytic Capacitors - Axial Leaded 5300UF 15V0
75-39D248G025JL639D248G025JL6Aluminium Electrolytic Capacitors - Axial Leaded Aluminium Electrolytic Capacitors - Axial Leaded 2400uF 25volts0
567-680-125A680-125AHeat Sinks Heat Sinks Maximum Efficiency, Omnidirectional Heat Sink for TO-3, 31.8mm Height1
649-DILB8P223TLFDILB8P-223TLFIC & Component Sockets IC & Component Sockets 8P IC SOCKET1
649-DILB16P-223TLFDILB16P-223TLFIC & Component Sockets IC & Component Sockets 16P SOCKET42
649-DILB14P-223TLFDILB14P-223TLFIC & Component Sockets IC & Component Sockets 14P DIP SOCKET12
649-DILB24P-224TLFDILB24P-224TLFIC & Component Sockets IC & Component Sockets 24 POS DIP SOCKET2
649-DILB40P223TLFDILB40P-223TLFIC & Component Sockets IC & Component Sockets 40P DIP SOCKET STAMPED AND FORMED2
562-703W-00/53703W-00/53AC Power Entry Modules AC Power Entry Modules PCB Mount 7mm1
712-CONBNC004CONBNC004RF Connectors / Coaxial Connectors RF Connectors / Coaxial Connectors BNC Connector Jack, Female Socket 50 Ohm Bulkhead Mount, Solder Pot1
611-CN202J3RS215Q7CN202J3RS215Q7Rocker Switches Rocker Switches DPST 16A ON-OFF RED1
661-ELBK250E532AM20SELBK250ELL532AM20SAluminium Electrolytic Capacitors - Radial Leaded Aluminium Electrolytic Capacitors - Radial Leaded 25V 5300uF +30% Tol. AEC-Q2001
661-ELBK350E252AL20SELBK350ELL252AL20SAluminium Electrolytic Capacitors - Radial Leaded Aluminium Electrolytic Capacitors - Radial Leaded 35V 2500uF +30% Tol. AEC-Q2002
 
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