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• Hi. How long (msecs) is a single instruction cycle on the Membership Card? Walid
Message 1 of 7 , Jul 26, 2011
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Hi.

How long (msecs) is a single instruction cycle on the Membership Card?

Walid
• Depends. The Membership Card has a variable speed clock -- there is an RC circuit that provides the clock pulses and a pot to adjust the speed. On the
Message 2 of 7 , Jul 26, 2011
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Depends. The Membership Card has a variable speed clock -- there is an RC circuit that provides the clock pulses and a pot to adjust the speed. On the schematic it says that it's adjustable between 10 and 500 kHz. Each 1802 instruction cycle is divided into two parts, a fetch cycle and an execute cycle. Each fetch/execute takes 8 clock cycles. All of the instructions have one fetch and one execute cycle, except for the long branch and NOP instructions, which have one fetch and two execute cycles. Most time critical code avoids using long branch instructions for that reason. So, doing the math for a fetch/execute cycle -- at 10kHz each there are 10k/(2*8) = 625 instructions per second. At 500 kHz there are 31,250 instructions per second. I think that means 1600 mSecs at 10 kHz and 32 mSecs at 500 kHz. But I'm sure someone will correct me if I'm wrong... Chuck To: cosmacelf@yahoogroups.com
From: wmaalouli@...
Date: Tue, 26 Jul 2011 15:45:34 +0000
Subject: [cosmacelf] Membership card quick question

Hi.

How long (msecs) is a single instruction cycle on the Membership Card?

Walid

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• Then how does the 1861 (or equiv.) work? I thought it had to have a specific clock freq. of 3.579545 MHz / 2 for 1.7897725 MHz.
Message 3 of 7 , Jul 26, 2011
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Then how does the 1861 (or equiv.) work? I thought it had to have a
specific clock freq. of 3.579545 MHz / 2 for 1.7897725 MHz.
• You do need to be running at a particular frequency to make use of the 1861, but the membership card doesn t have an 1861 so its clock speed is not an issue.
Message 4 of 7 , Jul 26, 2011
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You do need to be running at a particular frequency to make use of the 1861, but the membership card doesn't have an 1861 so its clock speed is not an issue.

Dave

On Jul 26, 2011, at 10:45 PM, whd_whd_whd wrote:
> Then how does the 1861 (or equiv.) work? I thought it had to have a
> specific clock freq. of 3.579545 MHz / 2 for 1.7897725 MHz.
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• I wanted to add one to mine. And I thought I had read somewhere that someone had added one to theirs.
Message 5 of 7 , Jul 26, 2011
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I wanted to add one to mine. And I thought I had read somewhere that

--- In cosmacelf@yahoogroups.com, Dave Ruske <dave@...> wrote:
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> You do need to be running at a particular frequency to make use of the 1861, but the membership card doesn't have an 1861 so its clock speed is not an issue.
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> Dave
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> On Jul 26, 2011, at 10:45 PM, whd_whd_whd wrote:
> > Then how does the 1861 (or equiv.) work? I thought it had to have a
> > specific clock freq. of 3.579545 MHz / 2 for 1.7897725 MHz.
• I suppose an 1861 could be added, but one of the hardware changes I think you ll need to make is to use a crystal-based clock at the appropriate frequency.
Message 6 of 7 , Jul 26, 2011
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I suppose an 1861 could be added, but one of the hardware changes I think you'll need to make is to use a crystal-based clock at the appropriate frequency.

Dave

On Jul 26, 2011, at 10:50 PM, whd_whd_whd wrote:
> I wanted to add one to mine. And I thought I had read somewhere that
> someone had added one to theirs.

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• I guess I will have to attach an oscilloscope to the ELF and figure what my clock speed is then... I m interested in programming a clock, which is the reason
Message 7 of 7 , Jul 27, 2011
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I guess I will have to attach an oscilloscope to the ELF and figure what my clock speed is then... I'm interested in programming a clock, which is the reason for my initial question, but I guess this will unfortunately be restricted to my own Membership Card :(
When I built the kit, there was no mention of adjusting the RC pot. Lee, did you set the pot to a specific value prior to shipping the kits or they are randomly set by the manufacturer?

Walid

--- In cosmacelf@yahoogroups.com, Chuck Bigham <chuck@...> wrote:
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> Depends. The Membership Card has a variable speed clock -- there is an RC circuit that provides the clock pulses and a pot to adjust the speed. On the schematic it says that it's adjustable between 10 and 500 kHz. Each 1802 instruction cycle is divided into two parts, a fetch cycle and an execute cycle. Each fetch/execute takes 8 clock cycles. All of the instructions have one fetch and one execute cycle, except for the long branch and NOP instructions, which have one fetch and two execute cycles. Most time critical code avoids using long branch instructions for that reason. So, doing the math for a fetch/execute cycle -- at 10kHz each there are 10k/(2*8) = 625 instructions per second. At 500 kHz there are 31,250 instructions per second. I think that means 1600 mSecs at 10 kHz and 32 mSecs at 500 kHz. But I'm sure someone will correct me if I'm wrong... Chuck To: cosmacelf@yahoogroups.com
> From: wmaalouli@...
> Date: Tue, 26 Jul 2011 15:45:34 +0000
> Subject: [cosmacelf] Membership card quick question
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