Search found 10393 matches

by exxos
Fri Sep 08, 2017 2:07 pm
Forum: HARDWARE DISCUSSIONS
Topic: RTC + BOOSTER THOUGHTS
Replies: 2
Views: 1252

RTC + BOOSTER THOUGHTS

I designed the RTC for the falcon here https://www.exxoshost.co.uk/atari/last/storenew/#0089 though no reason why this cannot be mashed into the current V2.5 booster design. It could probably use the same address ranges as the falcon (or not). Though I have the booster PLD connected to the address b...
by exxos
Fri Sep 08, 2017 1:16 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

I had another thought to diode clamp the input voltage. Looking at the DB27308 diode by panasonic http://www.mouser.com/ds/2/315/DB27308_BED-219812.pdf DB2730800L.JPG Looking at the graphic, we get about 0.3V drop at 10mA. I'm guessing here at 0.5V undershoot and 68R resistor (0.5/68 = 7.35mA) . So ...
by exxos
Thu Sep 07, 2017 8:29 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

This is what I am using.. PROPERTY ATMEL {JTAG = ON}; PROPERTY ATMEL {LOGIC_DOUBLING = OFF}; PROPERTY ATMEL {CASCADE_LOGIC = OFF}; PROPERTY ATMEL {PREASSIGN keep}; property ATMEL {OUTPUT_FAST OFF}; property ATMEL {POWER_RESET ON}; property ATMEL {PIN_KEEP OFF}; Will try fast output while its working...
by exxos
Thu Sep 07, 2017 7:36 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

Finally got 16MHz working just... rev1.jpg Got about 100R on the CPU_CLK now. The 8MHz clock I put back 68R and 1K pull up PLD side. So now I have 16MHz CPU.. 16mhz.jpg ..and 16MHZ CPU & ROM 16mhzrom.jpg It's clear I am going to have to do a quick buffer board for these lines.. so probably 2 weeks w...
by exxos
Thu Sep 07, 2017 5:55 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

So I now tried 2 anti-parallel diodes in series with the PLD input, and its now working fine again. This really makes me wonder what other signals are causing the PLD to go screwy during other tests :roll: 25.JPG TOS104 & TOS206 now working. TOS206 reported some RAM faults, though with the scope pro...
by exxos
Thu Sep 07, 2017 5:08 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

yea not much difference. Are you always driving BG ? or is it going Z when not asserted by the CPU ? We had issues with the Atmel on the first 68020 card : DSACK0 = 'b'1; DSACK0.oe = 'b'0; /* Always off */ You would think this would keep the pin in high impedance state ... well it didn't !!!!!!! Th...
by exxos
Thu Sep 07, 2017 4:37 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

I looked into what the 1K resistor was doing with the signals.. NO RESISTOR 1-min.png WITH RESISTOR 2-min.png All I can really see is the DC OFFSET moving up by about 0.25V. The undershoot seems to "stop" at the 0v line, whereas before it got to about -0.5V. This makes me think towards "latch up" of...
by exxos
Thu Sep 07, 2017 3:45 pm
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

More updates.. not good :roll: Oddly TOS104 wasn't working, it kept coming up the TOS206 fuji which made so sense, then either nothing, or bombs. New ROM later, and I went back to a "stock" 8mhz system, where the PLD does nothing at all, other than buffer the 8mhz clock. I'm using the motherboard RO...
by exxos
Thu Sep 07, 2017 11:22 am
Forum: SEC 64MHZ BOOSTER
Topic: CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)
Replies: 532
Views: 88984

Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS

The "in line" resistor in series with the 8MHz clock has been changed from 68R to about 150R. Now the booster is happy running at 8MHz mode :) TOS206 seems stable also :) Next up to try and add some 16MHz booster logic. After that, I want to try re-routing the 32MHz shifter osc though the booster bo...
by exxos
Thu Sep 07, 2017 10:25 am
Forum: HARDWARE DISCUSSIONS
Topic: MegaBus retrofit possible?
Replies: 5
Views: 1633

Re: MegaBus retrofit possible?

It says in there, that "excessive capacitance may cause improper ST operation". So I guess trace and/or wirelength are an issue if building an adapter. They are talking about "load" on the bus. It's one reason I change the 10K/4.7K pull ups to 2.2K now. Noted in that doc, 64 clocks for bus error.. ...

Go to advanced search