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Search: Posts Made By: PeteAU
Forum: Hardware mods 06 May 2020, 05:57
Replies: 522
Views: 129,902
Posted By PeteAU
Good to know, I edited post 2, thanks. Freaky...

Good to know, I edited post 2, thanks. Freaky colours, orange and black silk.

Interesting 020 card you have there, I haven't seen that one before.
Forum: Hardware mods 13 February 2020, 02:20
Replies: 75
Views: 14,118
Posted By PeteAU
If you are going to tinker with this, take care...

If you are going to tinker with this, take care with the Kicad schematic. I think VMA (pin 19 of old 68000 socket) is driven wrongly. It should come out of a 74LS157 mux. IMO I would dump the 157s...
Forum: Hardware mods 10 February 2020, 11:01
Replies: 75
Views: 14,118
Posted By PeteAU
Yes, add this to your IDE board. I ebayed a...

Yes, add this to your IDE board. I ebayed a couple MC68HC000FNs :)

Did Iscord try your idea of changing the caps? Seems like a solvable problem. There is an error in the schematic of connecting...
Forum: Hardware mods 08 February 2020, 00:48
Replies: 75
Views: 14,118
Posted By PeteAU
Cute board, I like its simplicity and modest...

Cute board, I like its simplicity and modest aims. Did this used to work in 1992 and now it's a problem of layout and component selection?
Forum: Hardware mods 24 September 2019, 11:29
Replies: 522
Views: 129,902
Posted By PeteAU
I got the impression you want to add 512KB chip...

I got the impression you want to add 512KB chip RAM, to make a total of 1MB chip RAM and nothing else, right? If that's so, no gary adapter required!
Forum: Hardware mods 20 September 2019, 14:06
Replies: 522
Views: 129,902
Posted By PeteAU
How you described the jumpers sounds all good and...

How you described the jumpers sounds all good and correct. And the "8M EDO" sounds right too (it was probably 4 chips on a SIMM stick). It's got to be something simple, one out of 42 pins not well...
Forum: Hardware mods 31 March 2019, 08:10
Replies: 522
Views: 129,902
Posted By PeteAU
You have put extra DIP DRAMs onto the...

You have put extra DIP DRAMs onto the motherboard? Unfortunately, it won't work with this board. IIRC - my memory is vague - it won't be able to split out the second RAS (RAS1) and thus fail. Your...
Forum: Hardware mods 04 March 2019, 02:55
Replies: 14
Views: 1,847
Posted By PeteAU
It would be neat to recreate a different RAM-32...

It would be neat to recreate a different RAM-32 with SOJ pads on it. I also have a VXL-030 in the cupboard without any ram board, so it's useless. But nobody knows the RAM-32 pin-outs and there are a...
Forum: Hardware mods 26 January 2019, 07:35
Replies: 522
Views: 129,902
Posted By PeteAU
Hi patzik, I'm trying to help you out to...

Hi patzik,

I'm trying to help you out to avoid wasting boards/money on this:
- You used a different CAM file, so the ground plane changed. The margins are too tight in a few places. Look at the...
Forum: Hardware mods 24 December 2018, 01:04
Replies: 522
Views: 129,902
Posted By PeteAU
If you want to test it early, it's best to do...

If you want to test it early, it's best to do that BEFORE putting more than 1 RAM chip and the 74F139. After that, you'll need the gary adapter. I haven't looked at the circuit lately, but leaving...
Forum: Hardware mods 04 October 2018, 10:02
Replies: 522
Views: 129,902
Posted By PeteAU
Would the cheap board houses actually fabricate...

Would the cheap board houses actually fabricate that? I would have doubts, but show us a photo if they do.



It also needs to be blue to be cool.
Forum: Hardware mods 24 June 2018, 10:04
Replies: 19
Views: 4,627
Posted By PeteAU
Hi cmorley, I guess you're twiddling the A9...

Hi cmorley,

I guess you're twiddling the A9 during RAS/CAS to get 4 different regions in the RAM chip, hence the CPLD. Then you delay the RAS/CAS to the chip to give enough setup time for the...
Forum: Hardware mods 30 April 2018, 10:53
Replies: 522
Views: 129,902
Posted By PeteAU
Nope! RTC 62421A has a quartz crystal built-in.

Nope! RTC 62421A has a quartz crystal built-in.
Forum: Hardware mods 05 April 2018, 13:06
Replies: 522
Views: 129,902
Posted By PeteAU
Even EXRAM is "don't care" on a A500+ because...

Even EXRAM is "don't care" on a A500+ because it's not connected on the motherboard!

I looked for the B52/floppy BMP files but couldn't find them. Maybe I'll check another computer later.

Nice...
Forum: Hardware mods 03 April 2018, 04:45
Replies: 522
Views: 129,902
Posted By PeteAU
Just see post #2 and order your own straight from...

Just see post #2 and order your own straight from China. It's cheap & easy.
Forum: Hardware mods 08 February 2018, 05:11
Replies: 522
Views: 129,902
Posted By PeteAU
No schematic, but gerber files added to post #2...

No schematic, but gerber files added to post #2 (first page). No idea if they work though. Let us know the result.
Forum: Hardware mods 29 January 2018, 09:20
Replies: 522
Views: 129,902
Posted By PeteAU
Screwed? Yes. Do you already have PCBs ordered?...

Screwed? Yes. Do you already have PCBs ordered? Maybe I can dig out a SOJ40 variant I put somewhere.



It's normal for elecrow, but maybe 3 boards are scratched or imperfect?
Forum: Hardware mods 25 January 2018, 09:57
Replies: 522
Views: 129,902
Posted By PeteAU
Join JP9 on the motherboard, otherwise the two...

Join JP9 on the motherboard, otherwise the two RTC chips will fight each other.



You used all CMOS HC (not HCT) chips and it worked? Surprized...
Forum: Hardware mods 11 January 2018, 06:31
Replies: 522
Views: 129,902
Posted By PeteAU
Both my diagram or demolition's would work fine....

Both my diagram or demolition's would work fine. I would solder only 2 chips though.

---

So has somebody combined this with a TF530? Supposedly 4.0-4.5 MB RAM is plenty for WHDLoad?
Forum: Hardware mods 25 November 2017, 10:12
Replies: 522
Views: 129,902
Posted By PeteAU
My post actually says "Battery Holder: Some cheap...

My post actually says "Battery Holder: Some cheap ebay one.". There is no part number. They're $1 for ten.
Forum: Hardware mods 15 November 2017, 10:00
Replies: 522
Views: 129,902
Posted By PeteAU
Selecting 0.5 CHIP on the Gary board doesn't...

Selecting 0.5 CHIP on the Gary board doesn't actually make it happen, you're just informing it you have 0.5. To really get 0.5MB you would need to return JP2 (motherboard) to the original factory...
Forum: Hardware mods 04 November 2017, 03:36
Replies: 522
Views: 129,902
Posted By PeteAU
This is what I would do: C11: none C12: 100nF...

This is what I would do:
C11: none
C12: 100nF 0805
C13: none
C19: 4.7uF tantalum (10 volts or better)

That's pretty much exactly Commodore's circuit in the A501.
Forum: Hardware mods 03 November 2017, 13:42
Replies: 522
Views: 129,902
Posted By PeteAU
Nice! I bought all the parts for your IDE board...

Nice! I bought all the parts for your IDE board too, one day I'll build it. What's this flat-flex cable you have there?



I *think* you can only use the board as chipram on the A500+.
But maybe...
Forum: Hardware mods 03 November 2017, 11:01
Replies: 522
Views: 129,902
Posted By PeteAU
Dumb question: Did you close RAM enable jumper?...

Dumb question: Did you close RAM enable jumper? It's needed for any slow RAM. Have you tried 0.5 CHIP + 1.0MB SLOW settings on gary adapter? You could also try swapping the two SEL wires.
Forum: Hardware mods 20 October 2017, 12:07
Replies: 522
Views: 129,902
Posted By PeteAU
If you convert your 8A to a 1MB A500+ then 74F139...

If you convert your 8A to a 1MB A500+ then 74F139 and Gary Adapter are not used!
Edit: I miss-understood, you're putting a 139 on the motherboard for conversion.

Yes I reckon it's easier to put...
Forum: Hardware mods 20 October 2017, 11:35
Replies: 522
Views: 129,902
Posted By PeteAU
That wouldn't work very well thru the trapdoor....

That wouldn't work very well thru the trapdoor. You need to add the 0.5MB onboard DIP chips and turn it into a realistic A500+. Then you can use this board to add another 1.0 MB (2.0 MB total CHIP...
Forum: Hardware mods 29 September 2017, 07:31
Replies: 11
Views: 2,017
Posted By PeteAU
It might work, but it depends what chip is inside...

It might work, but it depends what chip is inside the mouse. You've got to crack open the case and look.

I did it with this PS2 mouse and it works well.
Forum: Hardware mods 23 September 2017, 01:44
Replies: 522
Views: 129,902
Posted By PeteAU
My only comment is that's too expensive. The...

My only comment is that's too expensive. The sockets, connectors and RTC could be much cheaper elsewhere.

P.S. I have posted rev B.6 (1st page). This should be finished for 2017 :)
Forum: Hardware mods 22 September 2017, 11:36
Replies: 522
Views: 129,902
Posted By PeteAU
Just 100nF for the RTC isn't enough. When you...

Just 100nF for the RTC isn't enough. When you flick the power switch off, the voltage on the RTC briefly dips way down (around 2V) and it will sometimes forget time/date. I watched it on a scope. It...
Forum: Hardware mods 20 September 2017, 12:19
Replies: 522
Views: 129,902
Posted By PeteAU
IMO C3, C6, C23, C11 are not needed - I run...

IMO C3, C6, C23, C11 are not needed - I run happily without them. Pads are there just in-case.

C13/C19 are alternatives. Only one of them is needed. Any value >=4.7uF will be fine. 2.2uF ceramic...
Forum: Hardware mods 19 September 2017, 13:51
Replies: 522
Views: 129,902
Posted By PeteAU
I successfully use: 74F00, 74HCT74 and 74F139....

I successfully use: 74F00, 74HCT74 and 74F139. Seems strange they wouldn't work for you. Are you sure it wasn't "HC" by accident?



Will be fine! It's a tiny change Mathesar suggested but won't...
Forum: Hardware mods 19 September 2017, 10:58
Replies: 522
Views: 129,902
Posted By PeteAU
Maybe there'll be a B.6, Mathesar pointed out...

Maybe there'll be a B.6, Mathesar pointed out another thing, it never ends :rolleyes

The main board BOM is unchanged. I would recommend the RTC62421 (search AliExpress).
Just another 74HCT00 and...
Forum: Hardware mods 18 September 2017, 11:31
Replies: 522
Views: 129,902
Posted By PeteAU
All-right, Rev B.5 is posted (see 2nd post, first...

All-right, Rev B.5 is posted (see 2nd post, first page).
Unless there's a major screw up, that's it for this year.
Let us know if you build it.
Forum: Hardware mods 14 September 2017, 13:07
Replies: 522
Views: 129,902
Posted By PeteAU
These are good points. Do you want to make the...

These are good points. Do you want to make the changes or does clicking things in Eagle make you feel ill? ;)

In the meantime I posted rev B.4 where I managed to remove 2 vias on the gary adapter...
Forum: Hardware mods 14 September 2017, 03:54
Replies: 522
Views: 129,902
Posted By PeteAU
The outline file is .GML and looks fine to me....

The outline file is .GML and looks fine to me. The unrouted 19 is just some signals that we don't want to route from the main board to gary.
Go on, splash the $4.90+post and give it a go :)
Forum: Hardware mods 13 September 2017, 12:56
Replies: 522
Views: 129,902
Posted By PeteAU
New revision of the board, somebody plz check it

Hi,

I combined Mathesar's new gary adapter, redrawn by Mq666 into one board:

(links removed)

Changes:
- Added a jumper for RTC enable.
- Added a footprint for SMD RTC chip, so you can...
Forum: Hardware mods 12 September 2017, 11:25
Replies: 522
Views: 129,902
Posted By PeteAU
No worries. They can be sold for profit, as long...

No worries. They can be sold for profit, as long as you release the modified design if somebody asks.



Will they work as a drop-in replacement of the original RTC chip?[/QUOTE]

Kind of, you...
Forum: Hardware mods 12 September 2017, 01:55
Replies: 522
Views: 129,902
Posted By PeteAU
Are you planning to make & sell these on an...

Are you planning to make & sell these on an online store? Just my hunch :)
Use a RTC-72421 & remove the crystal, they're calibration free and more accurate.
Forum: Hardware mods 10 September 2017, 10:50
Replies: 522
Views: 129,902
Posted By PeteAU
Actually it is a small bug on your board, you're...

Actually it is a small bug on your board, you're missing a trace to U1 from the middle pad. It's sometimes handy for testing plain old 512K boards without having to remove the gary adapter.

If you...
Forum: Hardware mods 09 September 2017, 14:03
Replies: 522
Views: 129,902
Posted By PeteAU
Are you sure your /XRAM (enable) isn't cut on the...

Are you sure your /XRAM (enable) isn't cut on the motherboard JP7A? People often did that in the old days for 1MB CHIP mod.

If I remove my enable jumper, it ends up mirroring C0 with D0 and...
Showing results 1 to 40 of 104

 
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