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deramp5113's latest activity
D
deramp5113
replied to the thread
SOL-20 0909 PATTERN
.
You need to look at following signals during the 1st four cycles after RESET is released: 1) U24p1, U24p2 2) U22p3, U22p11 This will...
Yesterday at 8:40 PM
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deramp5113
replied to the thread
SOL-20 0909 PATTERN
.
You‘ll also need to check U24 and U22 before passing off on item 4 Mike
Yesterday at 3:04 AM
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deramp5113
replied to the thread
SOL-20 0909 PATTERN
.
The 909090 pattern means the CPU is running properly and has fetched a RST 7 instruction (0xFF) at some point. Upon fetching RST 7, the...
Sunday at 10:17 PM
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deramp5113
replied to the thread
IMSAI 8080 with Cuter monitor + keyboard issue
.
Great!
Jul 13, 2022
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deramp5113
replied to the thread
IMSAI 8080 with Cuter monitor + keyboard issue
.
Remove the PCB from the key board frame and you can the “type” directly on the PCB pads wih your fingers and that typically works. Mike
Jul 11, 2022
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deramp5113
replied to the thread
IMSAI 8080 with Cuter monitor + keyboard issue
.
Since it‘s the original CUTER ROM, then the mods to the PIO board must be to make it looks the same to the CPU as the keyboard port on...
Jul 11, 2022
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deramp5113
replied to the thread
IMSAI 8080 with Cuter monitor + keyboard issue
.
To support the IMSAI PIO instead of the 3P+S board that CUTER expects for the keyboard, you may have a modified version of CUTER. If...
Jul 10, 2022
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deramp5113
replied to the thread
Heathkit H89 flyback transformer
.
Ask over in the Heath SEBHC group, someone there can help. https://groups.google.com/g/sebhc
Jul 4, 2022
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deramp5113
reacted to
megardi's post
in the thread
Any interest in a SOL-20 keyboard replacement?
with
Like
.
I have successfully created a Sol-20 Reproduction using Dave's great Sol-20 keyboard replacement. Might not have tackled this project if...
Jun 16, 2022
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deramp5113
replied to the thread
North Star Horizon power
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LOL, as usual, hindsight is 20/20 - so frustrating. We kept testing resistance +/-16v to ground and there was no short. We forgot to...
Jun 6, 2022
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deramp5113
replied to the thread
North Star Horizon power
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With the 1K resistor in-line to the motherboard, what is the voltage drop across the 1K resistor? I.e., is there +16v on the power...
Jun 4, 2022
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deramp5113
replied to the thread
North Star Horizon power
.
So it does not sound like a diode short on the power rails then. Forgive me if I'm duplicating suggestions already tried in this thread...
Jun 2, 2022
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deramp5113
replied to the thread
SWTPC Co-Res and 8K BASIC v2.3 tape data available
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Thank you both for your efforts. I've uploaded the complete version of the manual to the SWTPC section on the deramp website. Mike
Jun 2, 2022
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deramp5113
replied to the thread
North Star Horizon power
.
Sounds like the power supplies are cycling into self protect mode over and over. A 165 ohm load at 16v is less than 1.6 watts, so a...
Jun 2, 2022
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deramp5113
reacted to
bzotto's post
in the thread
SWTPC Co-Res and 8K BASIC v2.3 tape data available
with
Like
.
A while back I came by a couple original cassette tapes from SWTPC including the Co-Resident Editor/Assembler and the 2.3 version of 8K...
May 24, 2022
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